2020-08-22
癌症成因及预防
· Risk FactorsExpand
· 风险因素
· GeneticsExpand
· 遗传学
· 癌症预防简介
Risk Factors for Cancer
癌症风险因素（来源美国国家癌症研究所）
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Age, weight, exposure to carcinogens, and genetics can increase the risk of developing cancer. Learn more from this Did You Know? video produced by NCI's Surveillance, Epidemiology, and End Results (SEER) program.
年龄、体重、接触致癌物、及遗传因素可增加患癌风险。
It is usually not possible to know exactly why one person develops cancer and another doesn’t. But research has shown that certain risk factors may increase a person’s chances of developing cancer. (There are also factors that are linked to a lower risk of cancer. These are sometimes called protective risk factors, or just protective factors.)
一个人患癌，另一个人没有，其原因往往不得而知。但研究显示，某些风险因素会增加患癌风险（亦有与患癌风险更低相关的保护性因素）。
Cancer risk factors include exposure to chemicals or other substances, as well as certain behaviors. They also include things people cannot control, like age and family history. A family history of certain cancers can be a sign of a possible inherited cancer syndrome. (See the Hereditary Cancer Syndromes section for more information about inherited genetic mutations that can cause cancer.)
癌症风险因素包括化学物质或其他物质暴露，及某些行为，也包括人力无法控制的因素，例如年龄和家族史。某些癌症的家族史也许是潜在遗传性癌症综合征的体征。
Most cancer risk (and protective) factors are initially identified in epidemiology studies. In these studies, scientists look at large groups of people and compare those who develop cancer with those who don’t. These studies may show that the people who develop cancer are more or less likely to behave in certain ways or to be exposed to certain substances than those who do not develop cancer.
大多数癌症风险因素（及保护性因素）最早是在流行病学研究中被识别出来。在这些研究中，科学家着眼于大群体，将癌症患者和健康人相比较。这些研究显示，癌症患者拥有某些行为表现或接触某些物质的概率高于或低于健康人。
Such studies, on their own, cannot prove that a behavior or substance causes cancer. For example, the finding could be a result of chance, or the true risk factor could be something other than the suspected risk factor. But findings of this type sometimes get attention in the media, and this can lead to wrong ideas about how cancer starts and spreads. (See the Common Cancer Myths and Misconceptions page for more information.)
这样的研究本身无法证明某种行为或物质能致癌。例如，研究结果可能只是偶然的发现，或者，真正的风险因素不是那可疑风险因素。但这种研究的结果有时能受到媒体关注，让人对癌症如何开始和播散产生误解。
When many studies all point to a similar association between a potential risk factor and an increased risk of cancer, and when a possible mechanism exists that could explain how the risk factor could actually cause cancer, scientists can be more confident about the relationship between the two.
当很多研究都表明某项潜在风险因素和患癌风险更高相关，有一个可能的工作机制能解释风险因素如何致癌，科学家就会对这二者的关系更有信心。
The list below includes the most-studied known or suspected risk factors for cancer. Although some of these risk factors can be avoided, others—such as growing older—cannot. Limiting your exposure to avoidable risk factors may lower your risk of developing certain cancers.
以下的列表罗列了研究最多的癌症已知或可疑风险因素。虽然有些风险因素可避免，但有些风险因素不能，例如上年纪。限制接触可避免的风险因素可减少患上某些癌症的风险。
· Age
· 年龄
· Alcohol
· 酒类
· 致癌物
· 慢性炎症
· Diet
· 饮食
· Hormones
· 激素
· 免疫抑制
· 传染原
· Obesity
· 肥胖
· 放疗
· Sunlight
· 日光
· Tobacco
· 烟草
Related Resources
相关资源
· Cancer Prevention Overview (PDQ®)–Patient Version
· 癌症预防简介-患者版
· Updated: December 23, 2015
更新：2015年12月23日
Age and Cancer Risk
年龄和患癌风险（来源美国国家癌症研究所）
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Advancing age is the most important risk factor for cancer overall, and for many individual cancer types. According to the most recent statistical data from NCI’s Surveillance, Epidemiology, and End Results program, the median age of a cancer diagnosis is 66 years. This means that half of cancer cases occur in people below this age and half in people above this age. One-quarter of new cancer cases are diagnosed in people aged 65 to 74.
总体上，年纪大是癌症最重要的风险因素，很多癌症都是如此。根据美国国家癌症研究所监督、流行病学及最终结果计划最新的统计资料，中位癌症确诊年龄为66岁，这意味着半数癌症病例发生于66岁以下，半数癌症病例发生于66岁以上。1/4的新发癌症病例在年龄介乎65岁至74岁的人身上发生。
A similar pattern is seen for many common cancer types. For example, the median age at diagnosis is 61 years for breast cancer, 68 years for colorectal cancer, 70 years for lung cancer, and 66 years for prostate cancer.
很多常见的癌症都是类似的模式。例如，中位乳腺癌确诊年龄为61岁，结直肠癌为68岁，肺癌为70岁，前列腺癌为66岁。
But the disease can occur at any age. For example, bone cancer is most frequently diagnosed among people under age 20, with more than one-fourth of cases occurring in this age group. And 10 percent of leukemias are diagnosed in children and adolescents under 20 years of age, whereas only 1 percent of cancer overall is diagnosed in that age group. Some types of cancer, such as neuroblastoma, are more common in children or adolescents than in adults.
但癌症在任何年龄都会发生。例如，骨癌最常发生于20岁以下人群，1/4以上病例属于该年龄组。10%的白血病发生于年龄低于20岁的儿童和青少年人群，总体上，只有1%的癌症发生于该年龄组。与成年人群相比，有些癌症（例如成神经细胞瘤）在儿童和青少年人群中更常见。
Percent of New Cancers by Age Group: All Cancer Sites
SEER 18 2007-2011, All Races, Both Sexes
· Posted: April 29, 2015
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Age and Cancer Risk was originally published by the National Cancer Institute.”
Alcohol
酒类（来源美国国家癌症研究所）
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Drinking alcohol can increase your risk of cancer of the mouth, throat, esophagus, larynx (voice box), liver, and breast. The more you drink, the higher your risk. The risk of cancer is much higher for those who drink alcohol and also use tobacco.
饮酒会增加患上口腔癌、喉癌、食管癌、喉头癌、肝癌和乳腺癌的风险。饮酒越多，风险越高。同时饮酒和吸烟的人患癌风险会更高。
Doctors advise people who drink to do so in moderate amounts. The federal government’s Dietary Guidelines for Americans defines moderate alcohol drinking as up to one drink per day for women and up to two drinks per day for men.
医生建议饮酒者适量饮酒。美国联邦政府《美国人膳食指南》对适量饮酒的定义为女性每天最多一杯，男性每天最多两杯。
It has been suggested that certain substances in red wine, such as resveratrol, have anticancer properties. However, there is no evidence that drinking red wine reduces the risk of cancer.
研究显示，红葡萄酒中的某些物质（例如白藜芦醇）有抗癌特性。但没有证据表明饮红葡萄酒会减少患癌风险。
For more information, see the Alcohol and Cancer Risk fact sheet.
· Posted: April 29, 2015
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Alcohol was originally published by the National Cancer Institute.”
Cancer-Causing Substances in the Environment
环境致癌物（来源美国国家癌症研究所）
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Coal-fired power plant.
Credit: Wikimedia Commons, CC BY-SA 2.0
Cancer is caused by changes to certain genes that alter the way our cells function. Some of these genetic changes occur naturally when DNA is replicated during the process of cell division. But others are the result of environmental exposures that damage DNA. These exposures may include substances, such as the chemicals in tobacco smoke, or radiation, such as ultraviolet rays from the sun.
癌症由某些改变细胞功能的基因改变导致，有些自然而然地发生于细胞分裂期间，有些是接触环境危害导致DNA受损的结果，这些环境危害包括致癌物（例如烟草烟雾中的化学物质）或辐射（例如太阳紫外线）。
People can avoid some cancer-causing exposures, such as tobacco smoke and the sun’s rays. But others are harder to avoid, especially if they are in the air we breathe, the water we drink, the food we eat, or the materials we use to do our jobs. Scientists are studying which exposures may cause or contribute to the development of cancer. Understanding which exposures are harmful, and where they are found, may help people to avoid them.
人们可以避免接触致癌物，例如烟草烟雾和阳光。但有些致癌物会更难以避免，尤其存在于呼吸的空气中，喝的水中，吃的食物中，或工作时处理的材料中。科学家正研究接触哪些物质会导致或有助于癌症发展。理解有害物质，及其所在之处，可有助于避免接触它们。
The substances listed below are among the most likely carcinogens to affect human health. Simply because a substance has been designated as a carcinogen, however, does not mean that the substance will necessarily cause cancer. Many factors influence whether a person exposed to a carcinogen will develop cancer, including the amount and duration of the exposure and the individual’s genetic background. Learn more about Environmental Carcinogens and Cancer Risk.
以下列出的物质是可能性最大的致癌物，它们会影响人类健康。但仅仅因为某样物质被明确为致癌物不代表该物质一定能致癌。接触致癌物是否致癌受很多因素影响，包括分量和接触时长及个人遗传背景。请了解更多环境致癌物和癌症风险。
· 黄曲霉毒素
· 马兜铃酸
· Arsenic
· 砷
· Asbestos
· 石棉
· Benzene
· 苯
· 苯
· 铍
· 1,3-丁二烯
· Cadmium
· 镉
· 煤焦油和煤焦油沥青
· 焦炉排放气体
· Crystalline Silica (respirable size)
· 结晶二氧化硅（能呼吸的大小）
· Erionite
· 毛沸石
· 环氧乙烷
· 甲醛
· Hexavalent Chromium Compounds
· 六价铬化合物
· Indoor Emissions from the Household Combustion of Coal
· 家用煤燃烧的室内排放
· Mineral Oils: Untreated and Mildly Treated
· 矿物油：未经加工或轻度加工
· 镍化合物
· Radon
· 氡
· Secondhand Tobacco Smoke (Environmental Tobacco Smoke)
· 二手烟（环境烟草烟雾）
· Soot
· 煤烟
· Strong Inorganic Acid Mists Containing Sulfuric Acid
· 含硫酸的强无机酸雾
· Thorium
· 钍
· 三氯乙烯
· 氯乙烯
· 木屑
Related Resources
相关资源
· Environmental Carcinogens and Cancer Risk
· 环境致癌物和癌症风险
· National Toxicology Program’s (NTP) Report on Carcinogens
· 美国国家毒理学计划的致癌物报告
· Updated: December 11, 2018
更新：2018年12月11日
Chronic Inflammation
慢性炎症（来源美国国家癌症研究所）
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Inflammation is a normal physiological response that causes injured tissue to heal. An inflammatory process starts when chemicals are released by the damaged tissue. In response, white blood cells make substances that cause cells to divide and grow to rebuild tissue to help repair the injury. Once the wound is healed, the inflammatory process ends.
炎症是正常的生理学反应，使受伤组织得以治愈。当受损组织释放出化学物质，就开始发炎。作为响应，白血球会制造使细胞能分裂和生长的物质以重建组织，辅助伤口修复。伤口治愈后，就结束发炎。
In chronic inflammation, the inflammatory process may begin even if there is no injury, and it does not end when it should. Why the inflammation continues is not always known. Chronic inflammation may be caused by infections that don’t go away, abnormal immune reactions to normal tissues, or conditions such as obesity. Over time, chronic inflammation can cause DNA damage and lead to cancer. For example, people with chronic inflammatory bowel diseases, such as ulcerative colitis and Crohn disease, have an increased risk of colon cancer.
当发生慢性炎症，即使没伤口，也会开始发炎，且不会在该结束时结束。尚不十分清楚炎症持续的原因。慢性炎症可能由持续的感染、对正常组织发出的异常免疫反应或肥胖等问题导致。随时间推移，慢性炎症会导致DNA受损，最终会致癌。例如，慢性肠炎患者（例如溃疡性结肠炎和克罗恩病）会有更高的结肠癌风险。
Many studies have investigated whether anti-inflammatory medications, such as aspirin or non-steroidal anti-inflammatory drugs, reduce the risk of cancer. However, a clear answer is not yet available. For more information, see Aspirin to Reduce Cancer Risk.
很多研究探究了抗炎药（例如阿司匹林或非甾抗炎药）会不会减少患癌风险。但目前尚没有明确答案。
· Posted: April 29, 2015
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Chronic Inflammation was originally published by the National Cancer Institute.”
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Certain popular ideas about how cancer starts and spreads—though scientifically wrong—can seem to make sense, especially when those ideas are rooted in old theories. But wrong ideas about cancer can lead to needless worry and even hinder good prevention and treatment decisions. This page provides the latest science-based information about some common cancer myths and misconceptions.
关于癌症如何开始和播散，有些广为流传的想法虽然反科学，但似乎有道理，尤其这些想法植根于陈旧假想的时候。但关于癌症的错误想法或会导致不必要的担忧，甚至会有碍预防和治疗的决策。下文对一些癌症常见的误解提供一些基于科学的说明。
In the United States, the likelihood of dying from cancer has dropped steadily since the 1990s. Five-year survival rates for some cancers, such as breast, prostate, and thyroid cancers, now are 90 percent or better. The 5-year survival rate for all cancers combined is currently about 67 percent. For more information, see the Annual Report to the Nation on the Status of Cancer.
自从20世纪90年代以来，在美国，死于癌症的概率持续地下降。某些癌症（例如乳腺癌、前列腺癌及甲状腺癌）的5年生存率目前为90%或更高。全部癌症的5年生存率目前为67%左右。
It is important to note, however, that these rates are based on data from large numbers of people. How long an individual cancer patient will live and whether he or she will die from the disease depend on many factors, including whether the cancer is slow or fast growing, how much the cancer has spread in the body, whether effective treatments are available, the person’s overall health, and more.
但值得注意的是，这些生存率基于大群体数据。一个癌症患者能活多久，会不会死于癌症，取决于众多因素，包括癌症生长速度、癌症播散情况、治疗疗效和患者总体健康等。
No. Although research has shown that cancer cells consume more sugar (glucose) than normal cells, no studies have shown that eating sugar will make your cancer worse or that, if you stop eating sugar, your cancer will shrink or disappear. However, a high-sugar diet may contribute to excess weight gain, and obesity is associated with an increased risk of developing several types of cancer. For more information, see the NCI fact sheet on Obesity and Cancer.
不会。虽然研究显示癌细胞比健康细胞消耗更多葡萄糖，没研究显示摄入糖分会加剧癌症，若不摄入糖分，肿瘤就会缩小或消失。但高糖饮食可助长肥胖，而肥胖与几种癌症的风险更高相关。
No. Researchers have conducted studies on the safety of the artificial sweeteners (sugar substitutes) saccharin (Sweet 'N Low®, Sweet Twin®, NectaSweet®); cyclamate; aspartame (Equal®, NutraSweet®); acesulfame potassium (Sunett®, Sweet One®); sucralose (Splenda®); and neotame and found no evidence that they cause cancer in humans. All of these artificial sweeteners except for cyclamate have been approved by the Food and Drug Administration for sale in the United States. For more information, see the NCI fact sheet on Artificial Sweeteners and Cancer.
不会。关于人造甜味剂（糖的替代品）邻磺酰苯甲酰亚胺、环磺酸盐、阿斯巴甜代糖、乙酰氨基磺酸钾、三氯蔗糖和纽甜的安全性，研究人员进行了一些研究，没找到证据表明它们会致癌。除了环磺酸盐，这些人造甜味剂都得到美国食品和药物管理局批准在美国销售。
In general, no. Cancer is not a contagious disease that easily spreads from person to person. The only situation in which cancer can spread from one person to another is in the case of organ or tissue transplantation. A person who receives an organ or tissue from a donor who had cancer in the past may be at increased risk of developing a transplant-related cancer in the future. However, that risk is extremely low—about two cases of cancer per 10,000 organ transplants. Doctors avoid the use of organs or tissue from donors who have a history of cancer.
总体而言，不会。癌症不是很容易就会人传人的传染病。癌症人传人只有一个情况，就是器官或组织移植。器官捐赠者曾患癌，接受其器官移植者会有更高的移植相关性患癌风险。但这种风险极其低，每10000例器官移植只有2例左右。医生会避免使用有患癌史的捐赠者的器官或组织。
In some people, cancers may be caused by certain viruses (some types of human papillomavirus, or HPV, for example) and bacteria (such as Helicobacter pylori). While a virus or bacterium can spread from person to person, the cancers they sometimes cause cannot spread from person to person. For more information about cancer-causing viruses and bacteria, see the NCI fact sheets on Helicobacter pylori and Cancer and HPV and Cancer and our page on Infectious Agents.
对于一些人，某些病毒（例如一些人类乳突病毒）和细菌（例如幽门螺杆菌）可致癌。虽然病毒或细菌具有人际传播能力，它们所导致的癌症却不会人传人。
To date, there is no convincing scientific evidence that links a person’s “attitude” to his or her risk of developing or dying from cancer. If you have cancer, it’s normal to feel sad, angry, or discouraged sometimes and positive or upbeat at other times. People with a positive attitude may be more likely to maintain social connections and stay active, and physical activity and emotional support may help you cope with your cancer. For more information, see the NCI fact sheet on Psychological Stress and Cancer.
目前，没有可信的科学证据表明心态和患癌风险或死于癌症风险相关。癌症患者有时感到伤心、生气或灰心，有时感到积极向上，皆为人之常情。心态积极者保持社交关系和活跃的概率会更高，身体活跃和情感支持有助于癌症应对。
The chance that surgery will cause cancer to spread to other parts of the body is extremely low. Following standard procedures, surgeons use special methods and take many steps to prevent cancer cells from spreading during biopsies or surgery to remove tumors. For example, if they must remove tissue from more than one area of the body, they use different surgical tools for each area. For information about how cancer spreads in the body, see our page on Metastatic Cancer.
手术导致癌症播散的概率极其低。遵守标准作业程序之下，外科医生会使用特别方法，采取很多步骤，以预防癌细胞在组织活检或手术期间播散。例如，如有必要从多于一处的部位切除组织，每个部位会用不同的外科工具。
No. Exposure to air will not make tumors grow faster or cause cancer to spread to other parts of the body. For information about how cancer spreads in the body, see our page on Metastatic Cancer.
不会。肿瘤接触空气后不会加快生长或导致播散。
No, not according to the best studies completed so far. Cancer is caused by genetic mutations, and cell phones emit a type of low-frequency energy that does not damage genes. For more information, see the NCI fact sheet on Cell Phones and Cancer Risk.
不会，根据目前最好的研究，不会。癌症由基因突变导致，手机发出低频能量，它不会损害基因。
No, not according to the best studies completed so far. Power lines emit both electric and magnetic energy. The electric energy emitted by power lines is easily shielded or weakened by walls and other objects. The magnetic energy emitted by power lines is a low-frequency form of radiation that does not damage genes. For more information, see the NCI fact sheet on Electromagnetic Fields and Cancer.
不会，根据目前最好的研究，不会。电源线发出电能和磁能，墙壁和其他物体会屏蔽或削弱这种电能，而磁能是低频辐射，不会损害基因。
No. Although some studies suggest that alternative or complementary therapies, including some herbs, may help patients cope with the side effects of cancer treatment, no herbal products have been shown to be effective for treating cancer. In fact, some herbal products may be harmful when taken during chemotherapy or radiation therapy because they may interfere with how these treatments work. Cancer patients should talk with their doctor about any complementary and alternative medicine products—including vitamins and herbal supplements—they may be using. For more information, see the Botanicals/Herbal Products section in Topics in Integrative, Alternative, and Complementary Therapies.
没有。尽管有些研究显示替代或补充疗法（包括草药）或会有助于癌症治疗副作用应对，目前没有研究显示草药制剂能有效治疗癌症。事实上，化疗或放疗期间，由于干扰治疗有效性，有些草药制剂可能有害。癌症患者应与医生谈论任何目前正服用的补充和替代医疗产品，包括维生素和草药补充剂。
Not necessarily. Cancer is caused by harmful changes (mutations) in genes. Only about 5 to 10 percent of cancers are caused by harmful mutations that are inherited from a person’s parents. In families with an inherited cancer-causing mutation, multiple family members will often develop the same type of cancer. These cancers are called “familial” or “hereditary” cancers.
不一定。癌症由有害的基因突变导致。只有5%到10%左右的癌症是从父母继承的有害突变导致的，在这种家族中，多位家庭成员往往会发生同样的癌症，称为家族性或遗传性癌症。
The remaining 90 to 95 percent of cancers are caused by mutations that happen during a person’s lifetime as a natural result of aging and exposure to environmental factors, such as tobacco smoke and radiation. These cancers are called “non-hereditary” or “spontaneous” cancers. For more information about the risk of getting cancer, see the NCI fact sheet on Genetic Testing for Hereditary Cancer Syndromes and Cancer Causes and Risk Factors.
剩余的90%到95%的癌症由后天性基因突变导致，这些突变因年老和环境危害（例如烟草烟雾和辐射）自然而然地发生，称为非遗传性或自发性癌症。
No. Based on the most recent data, about 38 percent of men and women will be diagnosed with cancer at some point during their lives. Most cancers are caused by genetic changes that occur throughout a person’s lifetime as a natural result of aging and exposure to environmental factors, such as tobacco smoke and radiation. Other factors, such as what kind of food you eat, how much you eat, and whether you exercise, may also influence your risk of developing cancer. For more information, see Cancer Causes and Risk Factors.
不。根据最新的资料，约38%的男性和女性在一生之中会被确诊为癌症。大多数癌症由后天性基因突变导致，是年老和接触环境危害（例如烟草烟雾和辐射）的自然结果，这还有其他因素的影响，包括食物、食量、锻炼与否，这些都会影响患癌风险。
No. The best studies so far have found no evidence linking the chemicals typically found in antiperspirants and deodorants with changes in breast tissue. For more information, see the NCI fact sheet on Antiperspirants/Deodorants and Breast Cancer.
不会。目前最好的研究没有找到证据表明止汗剂和除臭剂中的化学物质和乳腺组织变化相关。
There is no convincing scientific evidence that personal hair dye use increases the risk of cancer. Some studies suggest, however, that hairdressers and barbers who are regularly exposed to large quantities of hair dye and other chemical products may have an increased risk of bladder cancer. For more information, see the NCI fact sheet on Hair Dyes and Cancer Risk.
目前没有可信的科学证据表明染发产品会增加患癌风险。但有些研究显示定期接触大量染发产品和其他化学品的理发师会有更高的膀胱癌风险。
· Updated: August 22, 2018
更新：2018年8月22日
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Diet
饮食（来源美国国家癌症研究所）
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Scientists have studied many foods and dietary components for possible associations with increasing or reducing cancer risk.
科学家研究了很多食物和膳食组成，寻找它们和患癌风险的关系。
Credit: National Cancer Institute
Many studies have looked at the possibility that specific dietary components or nutrients are associated with increases or decreases in cancer risk. Studies of cancer cells in the laboratory and of animal models have sometimes provided evidence that isolated compounds may be carcinogenic (or have anticancer activity).
很多研究聚焦于某些膳食组成或营养和患癌风险可能的关系。实验室环境肿瘤细胞研究和动物模型肿瘤细胞研究有时能提供证据表明单独的化合物或会致癌（或具有抗癌活性）。
But with few exceptions, studies of human populations have not yet shown definitively that any dietary component causes or protects against cancer. Sometimes the results of epidemiologic studies that compare the diets of people with and without cancer have indicated that people with and without cancer differ in their intake of a particular dietary component.
但有些例外，人口研究没有明确表明膳食组成会致癌或防癌。有时，对比癌症患者和健康人的饮食的流行病学研究结果表明癌症患者和健康人在某种膳食组成的摄入上出现差异。
However, these results show only that the dietary component is associated with a change in cancer risk, not that the dietary component is responsible for, or causes, the change in risk. For example, study participants with and without cancer could differ in other ways besides their diet, and it is possible that some other difference accounts for the difference in cancer.
但这些结果显示膳食组成只是与患癌风险变化相关，而非导致患癌风险变化。例如，受研究的癌症患者和健康人可能在饮食以外的其他方面有差异，可能是其他的差异导致了癌症的差异。
When evidence emerges from an epidemiologic study that a dietary component is associated with a reduced risk of cancer, a randomized trial may be done to test this possibility. Random assignment to dietary groups ensures that any differences between people who have high and low intakes of a nutrient are due to the nutrient itself rather than to other undetected differences. (For ethical reasons, randomized studies are not generally done when evidence emerges that a dietary component may be associated with an increased risk of cancer.)
当流行病学研究得出证据表明膳食组成与患癌风险更低相关，就会进行随机试验证实这可能性。膳食组的随机分配确保营养摄入高者和营养摄入低者之间的差异是由于营养本身，而非其他未被发现的差异（基于道德理由，随机试验一般在有证据的情况下才进行）。
Scientists have studied many additives, nutrients, and other dietary components for possible associations with cancer risk. These include:
科学家研究了很多添加剂、营养，及其他膳食组成，寻找它们和患癌风险的关系，包括：
· Acrylamide
·Acrylamide is a chemical found in tobacco smoke and some foods. It can be produced when certain vegetables, such as potatoes, are heated to high temperatures. Studies in animal models have found that acrylamide exposure increases the risk for several types of cancer. However, there is no consistent evidence that dietary acrylamide exposure is associated with the risk of any type of cancer in humans. For more information, see the Acrylamide and Cancer Risk fact sheet.
· 丙烯酰胺是在烟草烟雾和一些食物中发现的化学物质。某些蔬菜（例如马铃薯）在加热至高温时就会产生丙烯酰胺。动物模型研究显示接触丙烯酰胺会增加患上几种癌症的风险。但膳食丙烯酰胺暴露与任何人类癌症风险相关缺乏证据一致性。
· Alcohol
·Although red wine has been suspected of reducing cancer risk, there is no scientific evidence for such an association. Also, alcohol is a known cause of cancer. Heavy or regular alcohol consumption increases the risk of developing cancers of the oral cavity (excluding the lips), pharynx (throat), larynx (voice box), esophagus, liver, breast, colon, and rectum. The risk of developing cancer increases with the amount of alcohol a person drinks. For more information, see the fact sheet on Alcohol and Cancer Risk.
· 酒类。虽然怀疑红葡萄酒会减少患癌风险，但没有科学证据表明这种关联性。而且，酒类是已知癌症成因。大量或定期喝酒会增加以下癌症风险：口腔癌（嘴唇除外）、喉癌、喉头癌、食管癌、肝癌、乳腺癌、结肠癌和直肠癌。酒量越大，患癌风险越高。
· Antioxidants
·Antioxidants are chemicals that block the activity of other chemicals, known as free radicals, that may damage cells. Laboratory and animal research has shown that exogenous antioxidants can help prevent the free radical damage associated with the development of cancer, but research in humans has not demonstrated convincingly that taking antioxidant supplements can help reduce the risk of developing or dying from cancer. Some studies have even shown an increased risk of some cancers. For more information, see the Antioxidants and Cancer Prevention fact sheet.
· 抗氧化剂是抑制可损害细胞的自由基活性的化学物质。实验室研究和动物研究均显示外源抗氧化剂或会有助于预防与患癌有关的自由基损伤，但人类研究仍缺乏令人信服的结果，表明服用氧化剂补充剂或会有助于减少患癌风险或死于癌症的风险。有些研究甚至显示某些癌症的风险增加。
· Artificial sweeteners
·Studies have been conducted on the safety of several artificial sweeteners, including saccharin, aspartame, acesulfame potassium, sucralose, neotame, and cyclamate. There is no clear evidence that the artificial sweeteners available commercially in the United States are associated with cancer risk in humans. For more information, see the Artificial Sweeteners and Cancer fact sheet.
· 人造甜味剂。对几种人造甜味剂的安全性进行了研究，包括邻磺酰苯甲酰亚胺、阿斯巴甜代糖、乙酰氨基磺酸钾、三氯蔗糖、纽甜和环磺酸盐。没有明显的证据表明美国市场上的人造甜味剂与人类患癌风险相关。
· Calcium
·Calcium is an essential dietary mineral that can be obtained from food and supplements. Research results overall support a relationship between higher intakes of calcium and reduced risks of colorectal cancer, but the results of studies have not always been consistent. Whether a relationship exists between higher calcium intakes and reduced risks of other cancers, such as breast and ovarian cancer, is unclear. Some research suggests that a high calcium intake may increase the risk of prostate cancer. For more information, see the fact sheet on Calcium and Cancer Prevention.
· 钙是主要的膳食矿物质，可从食物和补充剂摄取。总体上，研究结果支持更高的钙摄入和患上结直肠癌的风险更低相关，但这方面缺乏结果一致性。目前尚不清楚更高的钙摄入和其他癌症风险（例如乳腺癌和卵巢癌）更低是否相关。有些研究显示高钙摄入会增加前列腺癌风险。
· Charred meat
·Certain chemicals, called HCAs and PAHs, are formed when muscle meat, including beef, pork, fish, and poultry, is cooked using high-temperature methods. Exposure to high levels of HCAs and PAHs can cause cancer in animals; however, whether such exposure causes cancer in humans is unclear. For more information, see the Chemicals in Meat Cooked at High Temperatures and Cancer Risk fact sheet.
· 烧焦的肉类。采用高温烹调的牛肉、猪肉、鱼肉和禽鸟等肉类会产生某些化学物质，称为HCAs和PAHs。接触高水平的HCAs和PAHs可导致动物患癌，但目前尚不清楚这会不会导致人类患癌。
· Cruciferous vegetables
·Cruciferous vegetables contain chemicals known as glucosinolates, which break down into several compounds that are being studied for possible anticancer effects. Some of these compounds have shown anticancer effects in cells and animals, but the results of studies with humans have been less clear. For more information, see the Cruciferous Vegetables and Cancer Prevention fact sheet.
· 十字花科蔬菜含有称为芥子油苷的化学物质，其分解出的几种化合物的潜在抗癌作用受到研究，研究显示有些化合物在细胞和动物中有抗癌作用，但人类研究结果则没有那么明晰。
· Fluoride
·Fluoride in water helps to prevent and can even reverse tooth decay. Many studies, in both humans and animals, have shown no association between fluoridated water and cancer risk. For more information, see the Fluoridated Water fact sheet.
· 水中氟化物有助于预防、甚至能逆转蛀牙。无论是人类还是动物，很多研究皆显示含氟化物的水和患癌风险之间没有关联性。
· Garlic
·Some studies have suggested that garlic consumption may reduce the risk of developing several types of cancer, especially cancers of the gastrointestinal tract. However, the evidence is not definitive. For more information, see the Garlic and Cancer Prevention fact sheet.
· 大蒜。有些研究显示大蒜的摄入会减少患上几种癌症的风险，尤其是胃肠癌。但这并非确定性证据。
· Tea
·Tea contains polyphenol compounds, particularly catechins, which are antioxidants. Results of epidemiologic studies examining the association between tea consumption and cancer risk have been inconclusive. Few clinical trials of tea consumption and cancer prevention have been conducted and their results have also been inconclusive. For more information, see the fact sheet on Tea and Cancer Prevention.
· 茶含有多元酚化合物，尤其是儿茶酸，这些是抗氧化剂。针对茶的摄入和患癌风险之间的关联性的流行病学研究没有明确结果。少数茶的摄入和癌症预防临床试验也没有明确结果。
· Vitamin D
·Vitamin D helps the body use calcium and phosphorus to make strong bones and teeth. It is obtained primarily through exposure of the skin to sunlight, but it can also be obtained from some foods and dietary supplements. Epidemiologic studies in humans have suggested that higher intakes of vitamin D or higher levels of vitamin D in the blood may be associated with a reduced risk of colorectal cancer, but the results of randomized studies have been inconclusive. For more information, see the Vitamin D and Cancer Prevention fact sheet.
· 维生素D有助于人体利用钙和磷打造强硬的骨骼和牙齿，主要经由皮肤摄取自日光，也可摄取自某些食物和膳食补充剂。人类流行病学研究显示更高维生素D摄入或血液中维生素D水平更高可能与结直肠癌风险更低相关，但随机对照试验没有明确结果。
· Posted: April 29, 2015
发布：2015年4月29日
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Diet was originally published by the National Cancer Institute.”
Hormones
激素（来源美国国家癌症研究所）
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Estrogens, a group of female sex hormones, are known human carcinogens. Although these hormones have essential physiological roles in both females and males, they have also been associated with an increased risk of certain cancers. For instance, taking combined menopausal hormone therapy (estrogen plus progestin, which is a synthetic version of the female hormone progesterone) can increase a woman’s risk of breast cancer. Menopausal hormone therapy with estrogen alone increases the risk of endometrial cancer and is used only in women who have had a hysterectomy.
雌性激素是已知的人类致癌物。虽然这种激素对男女都有重要的生理学作用，却也与某些癌症的风险更高相关。例如，进行联合停经后激素治疗（雌性激素加上黄体酮）会增加女性乳腺癌风险。仅有雌性激素的停经后激素治疗会增加子宫内膜癌风险，仅限做了子宫切除术的女性患者使用。
A woman who is thinking about menopausal hormone therapy should discuss the possible risks and benefits with her doctor.
考虑停经后激素治疗的女性患者应与医生谈论其可能的风险和获益。
Studies have also shown that a woman’s risk of breast cancer is related to the estrogen and progesterone made by her ovaries (known as endogenous estrogen and progesterone). Being exposed for a long time and/or to high levels of these hormones has been linked to an increased risk of breast cancer. Increases in exposure can be caused by starting menstruation early, going through menopause late, being older at first pregnancy, and never having given birth. Conversely, having given birth is a protective factor for breast cancer.
研究也显示女性乳腺癌风险与其卵巢制造的雌性激素和黄体酮（称为内源性雌性激素和黄体酮）相关。长期暴露及/或高水平的这些激素的暴露与乳腺癌风险更高相关。月经期早来、更年期迟来、初次怀孕年纪较大、从不生育会导致暴露增加。反之，曾生育是乳腺癌的保护性因素。
Diethylstilbestrol (DES) is a form of estrogen that was given to some pregnant women in the United States between 1940 and 1971 to prevent miscarriages, premature labor, and related problems with pregnancy. Women who took DES during pregnancy have an increased risk of breast cancer. Their daughters have an increased risk of a cancer of the vagina or cervix. The possible effects on the sons and grandchildren of women who took DES during pregnancy are being studied.
乙烯雌酚（DES）是一种雌性激素，自1940年至1971年，在美国，这被给予一些怀孕妇女以预防流产、早产及怀孕相关性问题。怀孕期服用乙烯雌酚的妇女会有更高的乳腺癌风险。她们的女儿会有更高的阴道癌或子宫颈癌风险。对她们的儿子和孙子可能起的作用正在研究当中。
For more information, see the following fact sheets:
如欲了解更多信息，请看看以下的资料：
· Oral Contraceptives and Cancer Risk
· 口服避孕药和患癌风险
· Menopausal Hormone Therapy and Cancer
· 停经后激素治疗和癌症
· Reproductive History and Cancer Risk
· 生殖史和患癌风险
· Diethylstilbestrol (DES) and Cancer
· 乙烯雌酚和癌症
Related Resources
相关资源
· Breast Cancer Prevention (PDQ®)–Patient Version
· 乳腺癌预防-患者版
· Endometrial Cancer Prevention (PDQ®)–Patient Version
· 子宫内膜癌预防-患者版
· Posted: April 29, 2015
发布：2015年4月29日
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Hormones was originally published by the National Cancer Institute.”
Immunosuppression
免疫抑制（来源美国国家癌症研究所）
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Many people who receive organ transplants take medications to suppress the immune system so the body won’t reject the organ. These "immunosuppressive" drugs make the immune system less able to detect and destroy cancer cells or fight off infections that cause cancer. Infection with HIV also weakens the immune system and increases the risk of certain cancers.
很多接受器官移植的患者服药抑制免疫系统，以便身体不会排斥器官。这些免疫抑制剂会削弱免疫系统发现和消灭肿瘤细胞或抗击致癌性感染的能力。感染人类免疫缺陷病毒也会削弱免疫系统，并增加患上某些癌症的风险。
Research has shown that transplant recipients are at increased risk of a large number of different cancers. Some of these cancers can be caused by infectious agents, whereas others are not. The four most common cancers among transplant recipients and that occur more commonly in these individuals than in the general population are non-Hodgkin lymphoma (NHL) and cancers of the lung, kidney, and liver. NHL can be caused by Epstein-Barr virus (EBV) infection, and liver cancer by chronic infection with the hepatitis B (HBV) and hepatitis C (HCV) viruses. Lung and kidney cancers are not generally thought to be associated with infection.
研究显示接受器官移植者会有更高的患上大量不同癌症的风险，有些癌症由传染原导致，有些不是。接受器官移植者中最常见的四种癌症（比一般大众更常见）是非霍奇金淋巴瘤(NHL) 、肺癌、肾癌和肝癌。非霍奇金淋巴瘤由eb病毒导致，肝癌由乙型肝炎（HBV）和丙型肝炎（HCV）等慢性感染导致。肺癌和肾癌一般不被认为与感染有关。
People with HIV/AIDS also have increased risks of cancers that are caused by infectious agents, including EBV; human herpesvirus 8, or Kaposi sarcoma-associated virus; HBV and HCV, which cause liver cancer; and human papillomavirus, which causes cervical, anal, oropharyngeal, and other cancers. HIV infection is also associated with increased risks of cancers that are not thought to be caused by infectious agents, such as lung cancer.
艾滋病患者也会有更高的患上传染原导致的癌症的风险，这些传染原包括eb病毒、人类疱疹病毒8、或卡波西肉瘤相关性病毒、可导致肝癌的乙型肝炎和丙型肝炎、以及可导致子宫颈癌、肛门癌、口咽癌和其他癌症的人类乳突病毒。艾滋病感染也与不被认为由传染原导致的癌症（例如肺癌）风险更高相关。
For more information, see the HIV Infection and Cancer Risk fact sheet and the video on Transplant-Associated Immunosuppression and Cancer.
· Posted: April 29, 2015
发布：2015年4月29日
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Immunosuppression was originally published by the National Cancer Institute.”
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A human T cell (blue) under attack by HIV (yellow), the virus that causes AIDS.
Credit: National Cancer Institute
Certain infectious agents, including viruses, bacteria, and parasites, can cause cancer or increase the risk that cancer will form. Some viruses can disrupt signaling that normally keeps cell growth and proliferation in check. Also, some infections weaken the immune system, making the body less able to fight off other cancer-causing infections. And some viruses, bacteria, and parasites also cause chronic inflammation, which may lead to cancer.
某些传染原，包括病毒、细菌和寄生虫，可能会致癌或增加患癌风险。有些病毒会干扰指示细胞正常生长和增殖的信号通路。而且，有些感染会削弱免疫系统，削弱身体抗击其他致癌性感染的能力。有些病毒、细菌和寄生虫也会导致慢性炎症，从而致癌。
Most of the viruses that are linked to an increased risk of cancer can be passed from one person to another through blood and/or other body fluids. As described below, you can lower your risk of infection by getting vaccinated, not having unprotected sex, and not sharing needles.
大多数与癌症风险更高相关的病毒可能会通过血液及/或其他体液人传人。通过接种疫苗、进行安全性生活、不共用针头可降低感染风险。
· Hepatitis B Virus and Hepatitis C Virus (HBV and HCV)
· Human Immunodeficiency Virus (HIV)
· Human Papillomaviruses (HPVs)
· Human T-Cell Leukemia/Lymphoma Virus Type 1 (HTLV-1)
· Kaposi Sarcoma-Associated Herpesvirus (KSHV)
· Merkel Cell Polyomavirus (MCPyV)
· Helicobacter pylori (H. pylori)
EBV, a type of herpes virus, causes mononucleosis as well as certain types of lymphoma and cancers of the nose and throat. EBV is most commonly transmitted by contact with saliva, such as through kissing or by sharing toothbrushes or drinking glasses. It can also be spread by sexual contact, blood transfusions, and organ transplantation. EBV infection is lifelong. More than 90% of people worldwide will be infected with EBV during their lifetime, and most do not develop any symptoms. There is no vaccine to prevent EBV infection and no specific treatment for EBV infection.
eb病毒是一种疱疹病毒，会导致单核细胞增多症及某些淋巴瘤、鼻癌和喉癌。eb病毒最常见的传播途径是唾液接触，例如通过接吻或共用牙刷或水杯，也可通过性接触、输血和器官移植传播。eb病毒感染是终生的。世界上90%以上的人在其一生之中会感染eb病毒，大多数的人不会有任何症状。没有疫苗能预防eb病毒感染，eb病毒也没有相应的治疗方法。
Chronic infections with HBV or HCV can cause liver cancer. Both viruses can be transmitted via blood (for example, by sharing needles or through blood transfusions) and from mother to baby at birth. In addition, HBV can be transmitted via sexual contact.
乙型肝炎或丙型肝炎等慢性感染会导致肝癌。两种病毒都可通过血液（例如共用针头或输血）传播，还有母婴传播。另外，乙型肝炎可通过性接触传播。
Since the 1980s, infants in the United States and most other countries have been routinely vaccinated against HBV infection. Experts recommend that adults who have not been vaccinated against HBV and are at increased risk of HBV infection get vaccinated as soon as possible. Vaccination is especially important for health care workers and other professionals who come into contact with human blood.
自从20世纪80年代以来，美国婴儿和大多数其他国家的婴儿都例行接种疫苗，预防乙型肝炎感染，专家建议没接种的成人和乙型肝炎高危人群尽快接种。疫苗对医疗保健人员和工作中接触人类血液的人尤其重要。
The U.S. Centers for Disease Control and Prevention (CDC) also recommends that everyone in the United States born from 1945 through 1965, and other populations at increased risk for HCV infection, be tested for HCV. Although there is not currently a vaccine against HCV, new therapies can cure people of HCV infection. If you think you may be at risk for HBV or HCV infection, ask your doctor about being tested. These infections do not always cause symptoms, but tests can show whether you have the virus. If so, your doctor may suggest treatment. Also, your doctor can tell you how to keep from infecting other people.
美国疾病控制与预防中心也建议1945年至1965年出生的美国人和丙型肝炎高危人群进行丙型肝炎筛查。虽然目前没有丙型肝炎疫苗，有些新型治疗方法可以治愈丙型肝炎。如果认为自身有乙型肝炎或丙型肝炎风险，请要求医生开具相关检查的处方。这些感染不一定会引起症状，但检查可显示身体有没有病毒。如被感染，医生可以建议治疗，还会指导如何避免传染他人。
HIV is the virus that causes acquired immunodeficiency syndrome (AIDS). HIV does not cause cancer itself, but infection with HIV weakens the immune system and makes the body less able to fight off other infections that cause cancer. People infected with HIV have increased risks of a number of cancers, especially Kaposi sarcoma, lymphomas (including both non-Hodgkin lymphoma and Hodgkin disease), and cancers of the cervix, anus, lung, liver, and throat.
艾滋病病毒会导致获得性免疫缺陷综合症（AIDS）。艾滋病病毒不会致癌，但感染艾滋病会削弱免疫系统，削弱身体抗击其他致癌性感染的能力。艾滋病患者会有更高的癌症风险，尤其是卡波西肉瘤、淋巴瘤（包括非霍奇金淋巴瘤和霍奇金病），以及子宫颈癌、肛门癌、肺癌、肝癌和喉癌。
HIV can be transmitted via blood and through sexual contact. Men who have unprotected sex with other men and people who share needles for injection drug use are at the highest risk of acquiring HIV infection; heterosexual individuals who have unprotected sex with multiple partners are at the next highest risk.
艾滋病病毒可通过血液和性接触传播。没有做好保护措施，与其他男性发生性行为的男性，与他人共用针头注射毒品的人有最高的艾滋病风险；异性恋者没有做好保护措施，与多位性伴侣发生性关系，是风险第二高者。
People can be infected with HIV for years before they begin to develop symptoms. If you think you may be at risk for HIV infection, ask your doctor about being tested. If you test positive, your doctor can prescribe highly effective antiviral treatment and can tell you how to keep from infecting other people. For more information, see the HIV Infection and Cancer Risk fact sheet.
有可能感染艾滋病病毒多年后才出现症状。如果认为有艾滋病风险，请要求医生开具检查处方。如果检查结果为阳性，医生会开具高度有效的抗病毒治疗处方，也可以告诉患者如何避免传染给其他人。
Infection with high-risk types of HPV cause nearly all cervical cancers. They also cause most anal cancers and many oropharyngeal, vaginal, vulvar, and penile cancers. High-risk HPVs spread easily through direct sexual contact, including vaginal, oral, and anal sex. Several vaccines have been developed that prevent infection with the types of HPV that cause most HPV-associated cancers. In the United States, experts recommend that children be vaccinated at age 11 or 12, but children as young as age 9 and adults as old as 26 can also be vaccinated.
感染高风险人类乳头瘤病毒会导致几乎全部子宫颈癌，也会导致大多数肛门癌及很多口咽癌、阴道癌、外阴癌和阴茎癌。高风险人类乳头瘤病毒会轻易地通过直接性接触播散，包括通过阴道、口腔和肛门进行的性行为。为此研发了几种疫苗，预防导致大多数人类乳头瘤病毒相关性癌症的人类乳头瘤病毒感染。在美国，专家建议11岁或12岁的儿童接种疫苗，但年龄低至9岁的儿童或年龄高至26岁的成人也可以接种。
Cervical cancer screening can be used to detect signs of HPV infections in the cervix. Although HPV infections themselves cannot be treated, the cervical abnormalities that these infections can cause over time can be treated. For more information, see the HPV and Cancer, Human Papillomavirus (HPV) Vaccines, and Pap and HPV Testing fact sheets.
子宫颈癌筛查可用于发现位于子宫颈的人类乳头瘤病毒感染体征。虽然人类乳头瘤病毒感染本身无法治疗，但这种感染带来的子宫颈异常可以治疗。
HTLV-1 can cause an aggressive type of non-Hodgkin lymphoma called adult T-cell leukemia/lymphoma (ATLL). This virus spreads via blood (by sharing needles or through transfusions), through sexual contact, and from mother to child in the womb or via breastfeeding. Infection with this virus is more common in Japan, Africa, the Caribbean, and South America than in the United States. Most people with HTLV-1 infection do not have any symptoms or develop disease.
HTLV-1可能会导致侵袭性非霍奇金淋巴瘤，称为T细胞性白血病/淋巴瘤（ATLL）。这种病毒会通过血液（共用针头或输血）、性接触及母婴（宫内感染或喂养母乳）传播。与美国相比，这种病毒感染在日本、非洲、加勒比地区和南非更常见。大多数HTLV-1感染者没有任何症状或没发病。
Blood is routinely screened for HTLV-1 in the United States. There is no vaccine to prevent infection with this virus and no treatment if you are infected. If you think you may be at risk for HTLV-1 infection, ask your doctor about being tested. If you test positive, your doctor can tell you how to keep from infecting other people and monitor you for HTLV-1-induced disease.
在美国，HTLV-1筛查需要定期验血。无法通过接种疫苗预防这种病毒感染，感染者也没有方法治疗。如果认为具有HTLV-1风险，请要求医生开具检查处方。如果检查结果为阳性，医生可以告诉患者如何避免传染其他人，并监测其可引发的疾病。
Kaposi sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8 (HHV-8), can cause Kaposi sarcoma. KSHV can also cause primary effusion lymphoma and multicentric Castleman disease.
卡波西肉瘤相关性疱疹病毒（KSHV），也称为人类疱疹病毒8（HHV-8），可能会导致卡波西肉瘤，也可能会导致原发性渗出性淋巴瘤和多中心淋巴结增生。
KSHV is most commonly spread through saliva. It can also be spread through organ or bone marrow transplantation, and there is some evidence that it can be spread by blood transfusion, although this risk is minimized by practices followed in the United States such as blood storage and removal of white cells.
卡波西肉瘤相关性疱疹病毒通过唾液传播最常见，也可能通过器官移植或骨髓移植传播，有证据表明这可能会通过输血传播，但遵守美国规定的有关血液储存和白细胞移除等做法，这种风险可降至最低程度。
KSHV infection is generally limited to certain populations, and the way KSHV is spread varies among these populations. In sub-Saharan Africa and certain regions of Central and South America, where KSHV infection is relatively common, it is believed to spread by contact with saliva among family members. In Mediterranean countries (Italy, Greece, Israel, Saudi Arabia), where KSHV infection is present at intermediate levels, it is thought to spread by contact among children and by ill-defined routes among adults. Finally, in regions where KSHV infection is uncommon, such as the United States and Northern Europe, it appears to be mostly transmitted sexually, especially among men who have sex with men.
卡波西肉瘤相关性疱疹病毒感染一般仅发生于特定人群，其传播方式在这些人群中也有所不同。在撒哈拉以南非洲地区和中南美洲某些地区，卡波西肉瘤相关性疱疹病毒感染相对常见，有人认为这会通过家庭成员之间的唾液接触传播。而在地中海地区（意大利、希腊、以色列、沙地阿拉伯），卡波西肉瘤相关性疱疹病毒感染为中级别，有人认为这会通过儿童之间的接触和成人之间不明确的路径传播。最后在卡波西肉瘤相关性疱疹病毒感染不常见地区，例如美国和北欧，这似乎最可能通过性接触传播，尤其是男男性交。
Most people infected with KSHV do not develop cancer or show any symptoms, although those who also have HIV infection or are immunosuppressed for other reasons are more likely to develop KSHV-caused diseases. There is no vaccine to prevent KSHV infection and no therapy to treat infection. Men who have sex with men may be advised to avoid oral–anal contact (including use of saliva as a personal lubricant). And people who are infected with HIV can lower their risk of KSHV-related complications by using antiretroviral therapy.
虽然同时被艾滋病病毒感染或因其他原因免疫抑制患者更可能发展出卡波西肉瘤相关性疱疹病毒导致的疾病，但大多数卡波西肉瘤相关性疱疹病毒感染者不会患癌或显示任何症状。没有疫苗能预防卡波西肉瘤相关性疱疹病毒感染，没有方法能治疗这种感染。建议行男男性交者避免口肛接触（包括使用唾液作为润滑剂）。艾滋病患者可通过抗逆转录病毒疗法减少卡波西肉瘤相关性疱疹病毒相关性并发症风险。
MCPyV can cause Merkel cell carcinoma, a rare type of skin cancer. Most adults are infected with MCPyV, with transmission most likely occurring through casual direct (i.e., skin-to-skin) or indirect (i.e., touching a surface that an infected person has touched) contact in early childhood. The risk of Merkel cell carcinoma is greatly increased in elderly people and in younger adults with who are infected with HIV or are immunosuppressed for other reasons. Infection does not generally cause symptoms, and there are no treatments for MCPyV.
梅克尔多元癌细胞病毒可能会导致梅克尔细胞癌这种罕见的皮肤癌。大多数被梅克尔多元癌细胞病毒感染成人通过儿童早期不经意直接接触（例如皮肤接触）或间接接触（摸过感染者摸过的表面）传播最常见。梅克尔细胞癌风险在老年人群和被艾滋病病毒感染或因其他原因免疫抑制年轻成年人群中大大增加。感染一般不会产生症状，没有方法能治疗梅克尔多元癌细胞病毒。
H. pylori is a type of bacterium that can cause noncardia gastric cancer (a type of stomach cancer) and a type of lymphoma in the stomach lining, gastric MALT lymphoma. It can also cause stomach ulcers. The bacterium is thought to spread through consumption of contaminated food or water and direct mouth-to-mouth contact. The CDC estimates that approximately two-thirds of the world’s population harbors H. pylori, with infection rates much higher in developing countries than in developed nations. In most populations, the bacterium is first acquired during childhood.
幽门螺杆菌是一种细菌，可能会导致非贲门部胃癌和一种位于胃黏膜的淋巴瘤胃黏膜相关性淋巴瘤，也可能会导致胃溃疡。有人认为这种细菌会通过进食被污染食物或水和直接口对口接触传播。美国疾病控制与预防中心预测全球约2/3的人口被幽门螺杆菌感染，发展中国家的感染率高于发达国家。在大多数人群中，幽门螺杆菌最早在儿童时期接触到。
If you have stomach problems, see a doctor. Infection with H. pylori can be detected and treated with antibiotics.
如果患有胃部问题，请看医生。幽门螺杆菌感染有可靠的检测方法，可使用抗生素治疗。
For more information, see the Helicobacter pylori and Cancer fact sheet.
This parasitic flatworm (fluke), which is found in Southeast Asia, can cause cholangiocarcinoma (cancer of the bile ducts in the liver). People become infected when they eat raw or undercooked freshwater fish that contain the larvae. Antiparasitic drugs are used to treat the infection.
这种见于东南亚的寄生扁虫可能会导致胆管癌。人们在进食含有其幼虫的生的或未煮熟的淡水鱼时被感染。可使用抗寄生虫药治疗这种感染。
This parasitic flatworm (fluke), which lives in certain types of freshwater snails found in Africa and the Middle East, can cause bladder cancer. People become infected when infectious free-swimming flatworm larvae burrow into skin that has come into contact with contaminated fresh water. Antiparasitic drugs are used to treat the infection.
这种寄生扁虫在非洲和中东的淡水水域生存，可能会导致膀胱癌。人们在接触被污染的淡水时被自由游动的幼虫钻入皮肤而受感染。可使用抗寄生虫药治疗这种感染。
· Updated: January 12, 2017
更新：2017年1月12日
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Obesity
肥胖（来源美国国家癌症研究所）
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People who are obese may have an increased risk of several types of cancer, including cancers of the breast (in women who have been through menopause), colon, rectum, endometrium (lining of the uterus), esophagus, kidney, pancreas, and gallbladder.
肥胖者会有更高的癌症风险，这些癌症包括乳腺癌（绝经后妇女）、结肠癌、直肠癌、子宫内膜癌、食管癌、肾癌、胰腺癌和胆囊癌。
Conversely, eating a healthy diet, being physically active, and keeping a healthy weight may help reduce risk of some cancers. These healthy behaviors are also important to lessen the risk of other illnesses, such as heart disease, type II diabetes, and high blood pressure.
相反地，保持健康饮食、定期锻炼，及保持健康体重有助于减少癌症风险。这些健康行为对减少其他疾病风险也很重要，例如心脏病、II型糖尿病和高血压。
For more information, see the Obesity and Cancer and Physical Activity and Cancer fact sheets.
For more information on keeping a healthy weight, see the National Heart, Lung, and Blood Institute’s What Are Overweight and Obesity?
Related Resources
相关资源
· Cancer Trends Progress Report: Weight癌症趋势进展报告：体重
· Cancer Trends Progress Report: Physical Activity癌症趋势进展报告：运动
· Posted: April 29, 2015
发布：2015年4月29日
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Obesity was originally published by the National Cancer Institute.”
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Radiation of certain wavelengths, called ionizing radiation, has enough energy to damage DNA and cause cancer. Ionizing radiation includes radon, x-rays, gamma rays, and other forms of high-energy radiation. Lower-energy, non-ionizing forms of radiation, such as visible light and the energy from cell phones and electromagnetic fields, do not damage DNA and have not been found to cause cancer.
特定波长的辐射，称为电离辐射，具有足够的能量，可以损害DNA并致癌。电离辐射包括氡、X射线、伽马射线和其他高能辐射。低能的非电离辐射，例如可见光和手机和电磁场的能量，不会损害DNA，研究没显示这会致癌。
Radon is a radioactive gas given off by rocks and soil. Radon is formed when the radioactive element radium breaks down. Radium in turn is formed when the radioactive elements uranium and thorium break down. People who are exposed to high levels of radon have an increased risk of lung cancer.
氡是从岩石和土壤释放出的放射性气体。当放射性元素镭分解，就会形成氡。当放射性元素铀和钍分解，反过来又会形成镭。高水平氡暴露会增加肺癌风险。
If you live in an area of the country that has high levels of radon in its rocks and soil, you may wish to test your home for this gas. Home radon tests are easy to use and do not cost much. Most hardware stores sell test kits. There are many ways to lessen the amount of radon in a home to a safe level. For more information on radon, see the Radon page and the Radon and Cancer fact sheet.
如果居住地的岩石和土壤含氡量高，应进行住家氡检测。另外，氡的防护也有很多方法。
High-energy radiation, such as x-rays, gamma rays, alpha particles, beta particles, and neutrons, can damage DNA and cause cancer. These forms of radiation can be released in accidents at nuclear power plants and when atomic weapons are made, tested, or used.
高能辐射，例如X射线、伽马射线、阿尔法粒子、贝塔粒子和中子，都可能会损害DNA并致癌。这些辐射会在核电厂意外中或核武器制造、测试或使用期间被释放出来。
Certain medical procedures, such as chest x-rays, computed tomography (CT) scans, positron emission tomography (PET) scans, and radiation therapy can also cause cell damage that leads to cancer. However, the risks of cancer from these medical procedures are very small, and the benefit from having them is almost always greater than the risks.
某些医疗程序，例如胸部X射线、CT扫描、PET扫描和放疗，也可能会导致细胞损伤，从而致癌。但这些医疗程序的致癌风险很低，疗效的获益往往大于风险。
Talk with your doctor if you think you may be at risk for cancer because you were exposed to radiation. People considering CT scans should talk with their doctors about whether the procedure is necessary for them and about its risks and benefits. Cancer patients may want to talk with their doctors about how radiation treatment could increase their risk for a second cancer later on.
如果认为自身因辐射暴露而有患癌风险，请与医生谈谈。考虑CT扫描者应与医生谈谈这么做有没有必要，及其风险和获益。癌症患者应与医生谈谈放疗导致第二原发癌的风险。
For more information, see the fact sheets on Accidents at Nuclear Power Plants and Cancer Risk and Computed Tomography (CT) Scans and Cancer.
· Get the Facts about Exposure to I-131 Radiation
· 有关I-131辐射暴露的事实
· Interventional Fluoroscopy pdf file (141 KB)
· 介入性X线透视检查
· Radiation Therapy to Treat Cancer
· 癌症放疗
· Posted: April 29, 2015
发布：2015年4月29日
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Radiation was originally published by the National Cancer Institute.”
Sunlight
日光（来源美国国家癌症研究所）
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Credit: Veer
The sun, sunlamps, and tanning booths all give off ultraviolet (UV) radiation. Exposure to UV radiation causes early aging of the skin and skin damage that can lead to skin cancer.
日光、太阳灯和日光浴浴房都会发送紫外线。紫外线暴露会导致皮肤早衰和可能会导致皮肤癌的皮肤损伤。
People of all ages and skin tones should limit the amount of time they spend in the sun, especially between mid-morning and late afternoon, and avoid other sources of UV radiation, such as tanning beds. It is important to keep in mind that UV radiation is reflected by sand, water, snow, and ice and can go through windshields and windows. Even though skin cancer is more common among people with a light skin tone, people of all skin tones can develop skin cancer, including those with dark skin.
无论任何年龄，任何肤色，人们都应限制在阳光下的时间，尤其是从上午中段到下午末段，并避免接触其他紫外线源头，例如日晒床。记得沙滩、水面、雪地和冰面都会反射紫外线，紫外线会穿透挡风玻璃和窗户。虽然皮肤癌在浅肤色者中更常见，但全部肤色人群都会发生皮肤癌，包括深肤色者。
Follow these tips to protect your skin from sunlight:
遵照以下提示，保护皮肤免受日晒伤害：
· Wear a hat with a wide brim all around that shades your face, neck, and ears. Baseball caps and some sun visors protect only parts of your skin.
戴能遮挡脸部、颈部和耳朵的宽帽檐帽子。棒球帽和防晒板只能保护部分皮肤。
· Wear sunglasses that block UV radiation to protect the skin around your eyes.
戴太阳眼镜阻挡紫外线，保护眼部四周的皮肤。
· Wear long sleeves and long pants. Tightly woven, dark fabrics are best. Some fabrics are rated with an ultraviolet protection factor (UPF). The higher the rating, the greater the protection from sunlight.
穿长袖和长裤。编织紧密的深色布料最佳。有些布料具紫外线防护系数，评级越高，保护越大。
· Use sunscreen products with a sun protection factor (SPF) of at least 15. (Some doctors suggest using a product with an SPF of at least 30.) Apply the product’s recommended amount to uncovered skin 30 minutes before going outside, and apply again every two hours or after swimming or sweating.
防晒产品起码要防嗮系数SPF15。有些医生建议SPF30。外出前的30分钟，按照建议用量将产品涂抹在皮肤上，然后每隔两小时或游泳或出汗后再涂抹一次。
Keep in mind that the sun's rays...
记得阳光：
· are strongest between 10:00 a.m. and 4:00 p.m.
上午10点到下午4点最猛烈。
· can go through light clothing, windshields, windows, and clouds
可穿透浅色衣物、挡风玻璃、窗户和云层。
· are reflected by sand, water, snow, ice, and pavement
沙滩、水面、雪地、冰面和人行道都会反射。
Related Resources
相关资源
· 谁都可能患上皮肤癌
· Cancer Trends Progress Report: Sun Protection
· 癌症趋势进度报告：日光防护
· Updated: April 26, 2017
更新：2017年4月26日
If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Sunlight was originally published by the National Cancer Institute.”
Tobacco
烟草（来源美国国家癌症研究所）
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Tobacco use is a leading cause of cancer and of death from cancer. People who use tobacco products or who are regularly around environmental tobacco smoke (also called secondhand smoke) have an increased risk of cancer because tobacco products and secondhand smoke have many chemicals that damage DNA.
烟草使用是癌症主要的成因，也是癌症主要的死因。由于烟草产品和二手烟有很多损害DNA的化学物质，使用烟草产品者或经常接触二手烟者会有更高的癌症风险。
Tobacco use causes many types of cancer, including cancer of the lung, larynx (voice box), mouth, esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum, and cervix, as well as acute myeloid leukemia. People who use smokeless tobacco (snuff or chewing tobacco) have increased risks of cancers of the mouth, esophagus, and pancreas.
烟草使用会导致很多癌症，包括肺癌、喉头癌、口腔癌、食管癌、喉癌、膀胱癌、肾癌、肝癌、胃癌、胰腺癌、结直肠癌和子宫颈癌，及急性髓性白血病。无烟烟草使用者（鼻烟或咀嚼烟草）会有更高的口腔癌、食管癌和胰腺癌风险。
There is no safe level of tobacco use. People who use any type of tobacco product are strongly urged to quit. People who quit smoking, regardless of their age, have substantial gains in life expectancy compared with those who continue to smoke. Also, quitting smoking at the time of a cancer diagnosis reduces the risk of death.
烟草使用没有一个安全水平。任何烟草产品使用者都应戒掉。无论年龄多大，与继续吸烟者相比，戒烟者都会大幅增加预期寿命。而且，癌症确诊后戒烟会减少死亡风险。
For more information about the harms of tobacco use, see:
如欲了解更多烟草使用危害的信息，请看看：
· Harms of Smoking and Health Benefits of Quitting
· 吸烟危害与戒烟健康获益
· "Light" Cigarettes and Cancer Risk
· 点烟和癌症风险
· 吸烟和癌症
· 二手烟和癌症
· Smokeless Tobacco and Cancer
· 无烟烟草和癌症
For help quitting, see:
戒烟协助：
· How To Handle Withdrawal Symptoms and Triggers When You Decide To Quit Smoking
· 戒断反应和诱因应对
· Where To Get Help When You Decide To Quit Smoking
· 戒烟时从哪里获得帮助？
· Cigarette Smoking: Health Risks and How to Quit (PDQ®)
· 吸烟：健康风险和戒烟方法
Also, NCI offers free, confidential information about quitting tobacco by phone and online:
还有，美国国家癌症研究所提供有关戒烟的免费、保密信息：
· The NCI quitline, 1-877-44U-QUIT (1-877-448-7848), is available Monday through Friday, 9:00 a.m. to 9:00 p.m. ET.
美国国家癌症研究所戒烟热线1-877-448-7848（美国东部时间周一至周五上午9点到晚上9点）
· Smoking cessation counselors are available online by clicking the "Quitting Smoking" button in the LiveHelp pop-up, Monday through Friday, 9:00 a.m. to 9:00 p.m. ET.
点击“在线客服”弹出窗口的戒烟按钮，进行网上戒烟咨询（美国东部时间周一至周五上午9点到晚上9点）
Related Resources
相关资源
· The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General, 2014
· 吸烟健康方面的后果——50年的进步：2014年美国卫生局局长报告
· Cigarette Smoking: Health Risks and How to Quit (PDQ®)–Patient Version
· 吸烟：健康风险和戒烟方法——患者版
· Smokeless Tobacco and Public Health: A Global Perspective
· 无烟烟草和公共健康：全球角度
· Tobacco Control Monograph Series
· 烟草控制专题论文系列
· Updated: January 23, 2017
更新：2017年1月23日
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