- Guide to Breast Cancer
- Take the Breast Cancer Quiz
- Young Women & Breast Cancer
- Patient Comments: Breast Cancer Prevention - Mammograms
- Patient Comments: Breast Cancer Prevention - Genetic Tests
- Patient Comments: Breast Cancer Prevention - Foods
- Introduction to breast cancer prevention
- What are the biological causes of breast cancer?
- What are the risk factors for developing breast cancer?
- What is the importance of early breast cancer detection?
- What are the advantages and limitations of mammography?
- How frequently should women undergo mammography and breast examinations?
- What is the risk of radiation with repeated mammography screening over the years?
- How helpful are BRCA1 and BRCA2 genetic tests in identifying women at risk?
- What is the link between estrogen and breast cancer?
- What are breast cancer prevention treatments?
- Are there other breast cancer prevention measures?
- Breast Cancer Prevention Tips
What are the risk factors for developing breast cancer?
Gender and age
The most significant risk factors for breast cancer are gender and age. Men can develop breast cancer, but women are 100 times more likely to develop breast cancer than men. The risk of breast cancer also increases with age. Breast cancer is 400 times more common in women who are 50 years old as compared to those who are 20 years old.
Another important risk factor is having first-degree relatives (mother, sister, or daughter) with breast cancer or male relatives with prostate cancer. The risk is especially higher if both the mother and sister have had breast cancers, if the cancers in first-degree relatives occurred early in life (before age 50), or if the cancers in these relatives were found in both breasts. Having a male relative with breast cancer and having both relatives with breast and ovarian cancers also increase a woman's risk of developing breast cancer. Families with multiple members with other cancers may have a genetic defect leading to a higher risk of breast cancer.
Women who have inherited defective BRCA1, BRCA2, p53, and other DNA repair genes have an increased risk of developing breast cancer, sometimes at early ages, as discussed previously. But even in the absence of one of the known predisposing genetic defects, a strong family history may signify an increased risk because of genetic or environmental factors that are specific to that particular family. For example, increased risk in families could be due to exposure to similar environmental toxins in some cases.
Previous breast cancer
A woman with a history of breast cancer can develop a recurrence of the same breast cancer years later if the cancer cells had already spread to the lymph nodes or other parts of the body or if cancer cells were not all eliminated during treatment. A woman with previous breast cancer also has a three- to fourfold greater chance of developing another breast cancer in the opposite breast. In women who have been treated for breast cancer with breast conservation therapy (BCT), recurrence of cancer within the treated breast may also occur.
Other breast conditions
Even though most women with fibrocystic breasts and its related breast symptoms do not have increased risk of developing breast cancer, the lumpy texture and density of the breasts may hamper early cancer detection by breast examination or by mammography. Sometimes, women with fibrocystic breast changes have to undergo breast biopsies (obtaining small tissue samples from the breast for examination under a microscope) to make certain that palpable lumps are not cancerous.
Breast biopsies sometimes may reveal abnormal, though not yet cancerous, cell changes (called atypical hyperplasia). Women with atypical hyperplasia of the breast tissue have about a four- to five-fold enhanced likelihood of developing breast cancer. Some other benign cell changes in breast tissue are also associated with a slight increase (one and a half to two times normal) in risk. These are termed hyperplasia of breast tissue without atypia, sclerosing adenosis, fibroadenoma with complex features, and solitary papilloma.
The common benign breast tumor known as a fibroadenoma, unless it has unusual features under the microscope, does not confer an increased cancer risk.
Breast cancer risks can be additive. For example, women who have first-degree relatives with breast cancer and who also have atypical hyperplasia of the breast tissue have a much higher risk of developing breast cancer than women without these risk factors.
Women with a history of radiation therapy to the chest area as treatment for another cancer (such as Hodgkin's disease or non-Hodgkin's lymphoma) have a significantly increased risk for breast cancer, particularly if the radiation treatment was received at a young age.
Women who started their menstrual periods before age 12, those who have late menopause (after age 55), and those who had their first pregnancy after age 30, or who have never had children have a mildly increased risk of developing breast cancer (less than two times the normal risk). Early onset of menses, late arrival of menopause, and late or no pregnancies are all factors that increase a woman's lifetime level of estrogen exposure.
The use of hormone therapy (HT) after menopause, particularly estrogens and progesterone combined, leads to an increase in risk for development of breast cancer in women who are taking HT or who have recently used HT. This risk appears to return to normal if a woman has not used hormone therapy for 5 years or more. Similarly, some studies show birth control pills cause a small increased risk of breast cancer, but this risk also returns to normal after 10 years of nonuse. The decision whether to use hormone therapy or birth control pills involves weighing the risks versus the benefits and should be individualized after consulting one's doctor.
Dietary factors such as high-fat diets and alcohol consumption have also been implicated as factors that increase the risk for breast cancer. Despite rumors to the contrary, caffeine intake, antiperspirant use, bras, breast implants, miscarriages or abortions, and stress do not appear to increase the risk of breast cancer. It is important to remember that 75% of women who develop breast cancer have no risk factors other than age. Thus, screening and early detection are important to every woman regardless of the presence of risk factors.
The consumption of alcohol is associated with an increased risk of developing breast cancer, and this risk increases with the amount of alcohol consumed. Compared with nondrinkers, women who consume one alcoholic drink a day have a very small increase in risk. However, those who have two to five drinks daily have about one and a half times the risk of women who drink no alcohol.