癌症的预防是指采取某些行为降低患癌症的风险。通过癌症的预防，可降低某个群体或总人群中癌症的新发病例人数。这些措施也有望同时降低癌症所导致的死亡人数。
为了预防癌症的发生，科学家们着手研究和癌症发生相关的危险因素和保护因素。可以导致发病风险增加的因素被称为危险因素；而可以降低发病风险的因素则为保护因素。
癌症的危险因素有部分是可以避免的，但也有很多难以避免。例如，吸烟和特定的遗传基因都是某些癌症的风险因素，但我们只能避免吸烟。此外，规律锻炼和健康饮食可能是某些癌症的保护因素。增加这些可操作的保护因素和避免吸烟等风险因素可能降低患癌风险，但这些并不能保证你一生不会得癌症。
我们仍在研究预防癌症的其他方法，包括：
Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases of cancer in a group or population is lowered. Hopefully, this will lower the number of deaths caused by cancer.
To prevent new cancers from starting, scientists look at risk factors and protective factors. Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective factor.
Some risk factors for cancer can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some types of cancer, but only smoking can be avoided. Regular exercise and a healthy diet may be protective factors for some types of cancer. Avoiding risk factors and increasing protective factors may lower your risk but it does not mean that you will not get cancer.
Different ways to prevent cancer are being studied, including:
乳腺癌是一种起源于乳房组织的恶性肿瘤。
乳房组织主要由乳腺叶和乳腺导管组成。正常单侧乳房有15-20个乳腺叶，每个乳腺叶又由许多更小的乳腺小叶组成。乳腺小叶末端的腺泡可分泌乳汁。乳腺叶、乳腺小叶和腺泡彼此之间由导管相连。
乳房中分布有血管和淋巴管。淋巴管内的无色液体为淋巴液。淋巴液通过淋巴管在淋巴结之间流动。淋巴结形似小豆，具有过滤淋巴液，储存白细胞，抵抗感染和预防疾病的功能。乳房附近分布有多组淋巴结，包括腋下淋巴结、锁骨上淋巴结和胸部淋巴结。
了解更多关于乳腺癌的信息，请查看以下PDQ摘要:
乳腺癌是美国女性第二大常见癌症类型。
美国女性中，乳腺癌的发生率仅次于皮肤癌，高于所有其他癌种。在癌症导致的死亡中，乳腺癌仅次于肺癌，是美国女性的第二大癌症死因。然而，从2007年到2016年，美国乳腺癌的死亡人数每年稍有下降。此外，男性也可发生乳腺癌，但新发病例很少。
我国肿瘤登记数据显示，从2000-2014年，乳腺癌的发生率处于上升趋势，至2014年，已接近澳大利亚等发达国家水平。
Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.
The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called lobes, which have many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can make milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts.
Each breast also has blood vessels and lymph vessels. The lymph vessels carry an almost colorless, watery fluid called lymph. Lymph vessels carry lymph between lymph nodes. Lymph nodes are small, bean-shaped structures that filter lymph and store white blood cells that help fight infection and disease. Groups of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.
See the following PDQ summaries for more information about breast cancer:
Breast cancer is the second most common type of cancer in American women.
Women in the United States get breast cancer more than any other type of cancer except skin cancer. Breast cancer is second to lung cancer as a cause of cancer death in American women. However, deaths from breast cancer have decreased a little bit every year between 2007 and 2016. Breast cancer also occurs in men, but the number of new cases is small.
避免危险因素和增加保护因素可能有助于预防癌症。
规避癌症的危险因素有助于预防某些癌症。这些危险因素包括吸烟、超重和缺乏足够的锻炼。增加保护因素例如戒烟和锻炼，可能有助于预防某些癌症。关于如何降低癌症风险，请咨询医师或其他医疗专业人员。
NCI的乳腺癌风险评估工具可利用女性个体的已知危险因素来评估她在未来5年至90岁期间患乳腺癌的风险。这个在线工具主要供医疗服务人员使用。咨询关于乳腺癌风险的更多信息，请致电1-800-4-CANCER。
以下是乳腺癌的危险因素：
高龄
高龄是大多数癌症的主要危险因素。患癌症的风险会随着你年龄的增大而升高。
有乳腺癌或良性（非肿瘤）乳腺疾病史
有下列任何一种情况的女性患乳腺癌的风险增加：
乳腺癌的遗传风险
一级亲属（母亲、姐妹或女儿）患有乳腺癌的女性自身患乳腺癌的风险增加。
有相关基因或某些特定基因遗传改变的女性患乳腺癌的风险更高。由遗传基因改变引起的乳腺癌风险取决于基因突变的类型、癌症家族史及其他因素。
致密性乳腺
乳腺钼靶X线检查提示的乳腺组织致密，是乳腺癌的危险因素之一。风险程度取决于乳腺组织的致密程度。乳腺致密度高的女性比乳腺致密度低的女性患乳腺癌的风险更高。
乳腺致密度增高通常是一种遗传特征，但也可能发生于从未生育过、初次怀孕年龄大、绝经后使用激素或饮酒的女性中。
乳腺组织暴露于体内雌激素
雌激素是机体产生的一种激素。可以促进机体发育和维持女性性征。长时间暴露于雌激素可能增加患乳腺癌风险。女性在月经来潮后雌激素水平最高。
以下几种方式会增加女性雌激素暴露水平：
绝经期使用激素治疗
雌激素和孕激素等激素均可人工合成。针对不再产生雌激素的绝经后或行卵巢切除术的女性，可以单独或联合使用雌、孕激素药物来替代治疗。这种方法被称为激素替代疗法（HRT）或激素疗法（HT）。联合HRT/HT是雌激素和孕激素的联合治疗。这种类型的HRT/HT会增加患乳腺癌的风险。有研究显示，女性停止使用雌孕激素联合药物后，乳腺癌风险有所下降。
乳腺或胸部放疗
因为治疗癌症而接受胸部放疗的女性，乳腺癌的风险会增加，而且这种风险从治疗后第10年开始。增加的乳腺癌风险取决于放疗剂量和接受放疗的年龄。青春期乳腺开始发育时，如接受放疗，乳腺癌风险最高。
采用放疗治疗一侧乳腺癌，并不会增加对侧乳腺患癌症的风险。
BRCA1和BRCA2基因突变的女性暴露于类似胸部X线的辐射，可能会增加未来患乳腺癌的风险，特别是在20岁前接受过X线检查的女性。
肥胖
肥胖增加乳腺癌的风险，特别是绝经后未使用激素替代治疗的女性。
饮酒
饮酒增加乳腺癌风险。随着饮酒量增加，风险也增加。
以下是乳腺癌的保护因素：
减少乳房组织暴露于体内雌激素
减少女性乳房组织暴露于雌激素的时间，有助于预防乳腺癌。以下方式可减少雌激素暴露：
子宫切除术后接受单纯雌激素治疗、选择性雌激素受体调节剂或芳香化酶抑制剂和失活剂
子宫切除术后接受单纯雌激素治疗
单纯雌激素治疗可用于行子宫切除术后的女性。对于绝经前女性，单纯雌激素治疗可能降低乳腺癌风险。对于绝经后女性，子宫切除术后使用雌激素治疗可增加卒中和心血管疾病风险。
选择性雌激素受体调节剂
他莫昔芬和雷洛昔芬属于选择性雌激素受体调节剂（SERM）类药物。SERM药物在体内某些组织的作用类似于雌激素，但能阻断雌激素对其他组织的作用。
对于绝经前和绝经后的高风险女性，他莫昔芬治疗可降低雌激素受体阳性（ER阳性）乳腺癌和导管原位癌的风险。雷洛昔芬治疗也可降低绝经后女性患乳腺癌的风险。无论使用哪种药物，在治疗结束后，风险降低可持续几年或更长时间。需要注意的是，使用雷洛昔芬的患者骨折率较低。
使用他莫昔芬治疗会增加潮热、子宫内膜癌、卒中、白内障和血栓（尤其是肺部和腿部）的风险。与年轻女性相比，50岁以上女性患这些疾病的风险显著增加。50岁以下乳腺癌高风险女性使用他莫昔芬治疗可能获益最大。停用他莫昔芬后，这些疾病的风险会下降。关于使用这种药物的风险及获益，请咨询您的医生。
使用雷洛昔芬治疗会增加肺部和腿部血栓的风险，但不会增加子宫内膜癌的风险。对于合并骨质疏松症（骨密度降低）的绝经后女性，雷洛昔芬可降低高风险及低风险女性的乳腺癌风险。目前还不明确雷洛昔芬是否会对无骨质疏松症的女性产生同样的效果。关于使用这种药物的风险及获益，请咨询您的医生。
其他SERM药物正在进行临床试验。
芳香化酶抑制剂和失活剂
芳香化酶抑制剂（阿那曲唑、来曲唑）和失活剂（依西美坦）可降低有乳腺癌病史女性的复发和新发乳腺癌的风险。芳香化酶抑制剂还可降低患有以下疾病女性患乳腺癌的风险：
乳腺癌风险增高的女性，使用芳香化酶抑制剂可降低体内雌激素总量。绝经前，雌激素由卵巢和女性体内其他组织生成，包括脑、脂肪组织和皮肤。绝经后，卵巢停止生成雌激素，但是其他组织没有停止生成。芳香化酶抑制剂可用于阻断体内所有生成雌激素的芳香化酶的作用。芳香化酶失活剂可使酶无法发挥作用。
使用芳香化酶抑制剂可能造成的损害包括肌肉和关节疼痛、骨质疏松、潮热和疲劳感。
降低风险的乳腺切除术
有些乳腺癌高风险女性可能选择一种可降低患癌风险的乳腺切除术（在无乳腺癌体征时切除双侧乳腺）。这些女性罹患乳腺癌的风险要低得多，而且大多数人对她们患乳腺癌的风险的担心也较少。但是，在做出此决定之前，进行癌症风险评估，并咨询有关乳腺癌预防的不同方法，非常重要。
卵巢去势
体内大部分雌激素是由卵巢产生的。用于抑制或降低卵巢产生雌激素的治疗方法包括卵巢切除术、放疗和使用某些药物。这称为卵巢去势。
由于BRCA1和BRCA2基因的某些变化，导致乳腺癌风险升高的绝经前女性，可能会选择降低风险的卵巢切除术（在无乳腺癌体征时切除双侧卵巢）。这可降低体内的雌激素含量，并降低乳腺癌风险。降低乳腺癌风险的卵巢切除术也可降低绝经前女性因胸部辐射而增加的乳腺癌的风险。然而，在做这一决定前，进行乳腺癌风险评估和咨询是非常重要的。雌激素水平的突然下降可能导致更年期症状的开始。这些症状包括潮热、睡眠障碍、焦虑和抑郁。长期影响包括性欲下降、阴道干燥和骨密度降低。
足够的锻炼
每周锻炼4小时或以上的女性患乳腺癌的风险较低。对绝经前体重正常或偏瘦的女性，锻炼对乳腺癌风险的影响最大。
尚不清楚以下因素是否会影响乳腺癌的风险：
激素类避孕药
激素避孕药含有雌激素，或同时含有雌激素和孕激素。 一些研究表明，目前或最近使用激素避孕药的妇女患乳腺癌的风险可能会略有增加。 其他研究未显示使用激素避孕药的妇女患乳腺癌的风险增加。
一项研究表明，长时间使用激素类避孕药的女性患乳腺癌风险轻度升高。另一项研究表明，当妇女停用激素避孕药后，乳腺癌患病风险会随着停药时间的推移而降低。
需要更多的研究来明确激素类避孕药是否影响女性患乳腺癌风险。
环境
还没有研究证实暴露于环境中某些物质是否会增加患乳腺癌的风险，如化学物质。
研究表明，有些因素对乳腺癌风险有极少或无影响。
以下因素对乳腺癌风险有极少或无影响：
癌症预防临床试验用于研究癌症的预防方法。
癌症预防临床试验用于研究降低某些癌症的发病风险。有些癌症预防研究是在没有患过癌症但癌症风险增加的正常人群中进行的。有些癌症预防研究是在癌症患者中进行的，尝试预防新发同类癌症或降低其他类型癌症的风险。其他试验是在没有任何癌症风险因素的健康志愿者中进行的。
有些癌症预防临床试验的目的是明确人们采取的措施是否可以预防癌症。这些措施包括加强锻炼、戒烟，或服用某些药物、维生素、矿物质或食品补充剂。
预防乳腺癌的新方法正在临床试验研究当中。
关于美国国家癌症研究所（NCI）支持的临床试验信息，可以在NCI临床试验的搜索网页上找到。其他组织支持的临床试验可以在ClinicalTrials.gov网站上找到。
Avoiding risk factors and increasing protective factors may help prevent cancer.
Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
NCI's Breast Cancer Risk Assessment Tool uses a woman's risk factors to estimate her risk for breast cancer during the next five years and up to age 90. This online tool is meant to be used by a health care provider. For more information on breast cancer risk, call 1-800-4-CANCER.
The following are risk factors for breast cancer:
Older age
Older age is the main risk factor for most cancers. The chance of getting cancer increases as you get older.
A personal history of breast cancer or benign (noncancer) breast disease
Women with any of the following have an increased risk of breast cancer:
Inherited risk of breast cancer
Women with a family history of breast cancer in a first-degree relative (mother, sister, or daughter) have an increased risk of breast cancer.
Women who have inherited changes in the and genes or in certain other genes have a higher risk of breast cancer. The risk of breast cancer caused by inherited gene changes depends on the type of gene mutation, family history of cancer, and other factors.
Dense breasts
Having breast tissue that is dense on a mammogram is a factor in breast cancer risk. The level of risk depends on how dense the breast tissue is. Women with very dense breasts have a higher risk of breast cancer than women with low breast density.
Increased breast density is often an inherited trait, but it may also occur in women who have not had children, have a first pregnancy late in life, take postmenopausal hormones, or drink alcohol.
Exposure of breast tissue to estrogen made in the body
Estrogen is a hormone made by the body. It helps the body develop and maintain female sex characteristics. Being exposed to estrogen over a long time may increase the risk of breast cancer. Estrogen levels are highest during the years a woman is menstruating.
A woman's exposure to estrogen is increased in the following ways:
Taking hormone therapy for symptoms of menopause
Hormones, such as estrogen and progesterone, can be made into a pill form in a laboratory. Estrogen, progestin, or both may be given to replace the estrogen no longer made by the ovaries in postmenopausal women or women who have had their ovaries removed. This is called hormone replacement therapy (HRT) or hormone therapy (HT). Combination HRT/HT is estrogen combined with progestin. This type of HRT/HT increases the risk of breast cancer. Studies show that when women stop taking estrogen combined with progestin, the risk of breast cancer decreases.
Radiation therapy to the breast or chest
Radiation therapy to the chest for the treatment of cancer increases the risk of breast cancer, starting 10 years after treatment. The risk of breast cancer depends on the dose of radiation and the age at which it is given. The risk is highest if radiation treatment was used during puberty, when breasts are forming.
Radiation therapy to treat cancer in one breast does not appear to increase the risk of cancer in the other breast.
For women who have inherited changes in the BRCA1 and BRCA2 genes, exposure to radiation, such as that from chest x-rays, may further increase the risk of breast cancer, especially in women who were x-rayed before 20 years of age.
Obesity
Obesity increases the risk of breast cancer, especially in postmenopausal women who have not used hormone replacement therapy.
Drinking alcohol
Drinking alcohol increases the risk of breast cancer. The level of risk rises as the amount of alcohol consumed rises.
The following are protective factors for breast cancer:
Less exposure of breast tissue to estrogen made by the body
Decreasing the length of time a woman's breast tissue is exposed to estrogen may help prevent breast cancer. Exposure to estrogen is reduced in the following ways:
Taking estrogen-only hormone therapy after hysterectomy, selective estrogen receptor modulators, or aromatase inhibitors and inactivators
Estrogen-only hormone therapy after hysterectomy
Hormone therapy with estrogen only may be given to women who have had a hysterectomy. In these women, estrogen-only therapy after menopause may decrease the risk of breast cancer. There is an increased risk of stroke and heart and blood vessel disease in postmenopausal women who take estrogen after a hysterectomy.
Selective estrogen receptor modulators
Tamoxifen and raloxifene belong to the family of drugs called selective estrogen receptor modulators (SERMs). SERMs act like estrogen on some tissues in the body, but block the effect of estrogen on other tissues.
Treatment with tamoxifen lowers the risk of estrogen receptor-positive (ER-positive) breast cancer and ductal carcinoma in situ in premenopausal and postmenopausal women at high risk. Treatment with raloxifene also lowers the risk of breast cancer in postmenopausal women. With either drug, the reduced risk lasts for several years or longer after treatment is stopped. Lower rates of broken bones have been noted in patients taking raloxifene.
Taking tamoxifen increases the risk of hot flashes, endometrial cancer, stroke, cataracts, and blood clots (especially in the lungs and legs). The risk of having these problems increases markedly in women older than 50 years compared with younger women. Women younger than 50 years who have a high risk of breast cancer may benefit the most from taking tamoxifen. The risk of having these problems decreases after tamoxifen is stopped. Talk with your doctor about the risks and benefits of taking this drug.
Taking raloxifene increases the risk of blood clots in the lungs and legs, but does not appear to increase the risk of endometrial cancer. In postmenopausal women with osteoporosis (decreased bone density), raloxifene lowers the risk of breast cancer for women who have a high or low risk of breast cancer. It is not known if raloxifene would have the same effect in women who do not have osteoporosis. Talk with your doctor about the risks and benefits of taking this drug.
Other SERMs are being studied in clinical trials.
Aromatase inhibitors and inactivators
Aromatase inhibitors (anastrozole, letrozole) and inactivators (exemestane) lower the risk of recurrence and of new breast cancers in women who have a history of breast cancer. Aromatase inhibitors also decrease the risk of breast cancer in women with the following conditions:
In women with an increased risk of breast cancer, taking aromatase inhibitors decreases the amount of estrogen made by the body. Before menopause, estrogen is made by the ovaries and other tissues in a woman's body, including the brain, fat tissue, and skin. After menopause, the ovaries stop making estrogen, but the other tissues do not. Aromatase inhibitors block the action of an enzyme called aromatase, which is used to make all of the body's estrogen. Aromatase inactivators stop the enzyme from working.
Possible harms from taking aromatase inhibitors include muscle and joint pain, osteoporosis, hot flashes, and feeling very tired.
Risk-reducing mastectomy
Some women who have a high risk of breast cancer may choose to have a risk-reducing mastectomy (the removal of both breasts when there are no signs of cancer). The risk of breast cancer is much lower in these women and most feel less anxious about their risk of breast cancer. However, it is very important to have a cancer risk assessment and counseling about the different ways to prevent breast cancer before making this decision.
Ovarian ablation
The ovaries make most of the estrogen that is made by the body. Treatments that stop or lower the amount of estrogen made by the ovaries include surgery to remove the ovaries, radiation therapy, or taking certain drugs. This is called ovarian ablation.
Premenopausal women who have a high risk of breast cancer due to certain changes in the BRCA1 and BRCA2 genes may choose to have a risk-reducing oophorectomy (the removal of both ovaries when there are no signs of cancer). This decreases the amount of estrogen made by the body and lowers the risk of breast cancer. Risk-reducing oophorectomy also lowers the risk of breast cancer in normal premenopausal women and in women with an increased risk of breast cancer due to radiation to the chest. However, it is very important to have a cancer risk assessment and counseling before making this decision. The sudden drop in estrogen levels may cause the symptoms of menopause to begin. These include hot flashes, trouble sleeping, anxiety, and depression. Long-term effects include decreased sex drive, vaginal dryness, and decreased bone density.
Getting enough exercise
Women who exercise four or more hours a week have a lower risk of breast cancer. The effect of exercise on breast cancer risk may be greatest in premenopausal women who have normal or low body weight.
It is not clear whether the following affect the risk of breast cancer:
Hormonal contraceptives
Hormonal contraceptives contain estrogen or estrogen and progestin. Some studies have shown that women who are current or recent users of hormonal contraceptives may have a slight increase in breast cancer risk. Other studies have not shown an increased risk of breast cancer in women using hormonal contraceptives.
In one study, the risk of breast cancer slightly increased the longer a woman used hormonal contraceptives. Another study showed that the slight increase in breast cancer risk decreased over time when women stopped using hormonal contraceptives.
More studies are needed to know whether hormonal contraceptives affect a woman's risk of breast cancer.
Environment
Studies have not proven that being exposed to certain substances in the environment, such as chemicals, increases the risk of breast cancer.
Studies have shown that some factors have little or no effect on the risk of breast cancer.
The following have little or no effect on the risk of breast cancer:
Cancer prevention clinical trials are used to study ways to prevent cancer.
Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.
The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include exercising more or quitting smoking or taking certain medicines, vitamins, minerals, or food supplements.
New ways to prevent breast cancer are being studied in clinical trials.
Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government’s center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
This PDQ cancer information summary has current information about breast cancer prevention. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Screening and Prevention Editorial Board.
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials can be found online at NCI's website. For more information, call the Cancer Information Service (CIS), NCI's contact center, at 1-800-4-CANCER (1-800-422-6237).
PDQ is a registered trademark. The content of PDQ documents can be used freely as text. It cannot be identified as an NCI PDQ cancer information summary unless the whole summary is shown and it is updated regularly. However, a user would be allowed to write a sentence such as “NCI’s PDQ cancer information summary about breast cancer prevention states the risks in the following way: [include excerpt from the summary].”
The best way to cite this PDQ summary is:
PDQ® Screening and Prevention Editorial Board. PDQ Breast Cancer Prevention. Bethesda, MD: National Cancer Institute. Updated
Images in this summary are used with permission of the author(s), artist, and/or publisher for use in the PDQ summaries only. If you want to use an image from a PDQ summary and you are not using the whole summary, you must get permission from the owner. It cannot be given by the National Cancer Institute. Information about using the images in this summary, along with many other images related to cancer can be found in Visuals Online. Visuals Online is a collection of more than 3,000 scientific images.
The information in these summaries should not be used to make decisions about insurance reimbursement. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.
More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website’s E-mail Us.
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government’s center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
This PDQ cancer information summary has current information about breast cancer prevention. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Screening and Prevention Editorial Board.
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials can be found online at NCI's website. For more information, call the Cancer Information Service (CIS), NCI's contact center, at 1-800-4-CANCER (1-800-422-6237).
PDQ is a registered trademark. The content of PDQ documents can be used freely as text. It cannot be identified as an NCI PDQ cancer information summary unless the whole summary is shown and it is updated regularly. However, a user would be allowed to write a sentence such as “NCI’s PDQ cancer information summary about breast cancer prevention states the risks in the following way: [include excerpt from the summary].”
The best way to cite this PDQ summary is:
PDQ® Screening and Prevention Editorial Board. PDQ Breast Cancer Prevention. Bethesda, MD: National Cancer Institute. Updated
Images in this summary are used with permission of the author(s), artist, and/or publisher for use in the PDQ summaries only. If you want to use an image from a PDQ summary and you are not using the whole summary, you must get permission from the owner. It cannot be given by the National Cancer Institute. Information about using the images in this summary, along with many other images related to cancer can be found in Visuals Online. Visuals Online is a collection of more than 3,000 scientific images.
The information in these summaries should not be used to make decisions about insurance reimbursement. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.
More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website’s E-mail Us.