Risk factors
By Mayo Clinic staffA risk factor is anything that makes it more likely you'll get a particular disease. But having one or even several risk factors doesn't necessarily mean you'll develop cancer — many women who develop breast cancer have no known risk factors other than simply being women.
Factors that are associated with an increased risk of breast cancer include:
- Being female. Women are much more likely than men are to develop breast cancer.
- Increasing age. Your risk of breast cancer increases as you age. Women older than 55 have a greater risk than do younger women.
- A personal history of breast cancer. If you've had breast cancer in one breast, you have an increased risk of developing cancer in the other breast.
- A family history of breast cancer. If you have a mother, sister or daughter with breast cancer, you have a greater chance of being diagnosed with breast cancer. Still, the majority of people diagnosed with breast cancer have no family history of the disease.
- Inherited genes that increase cancer risk. Certain gene mutations that increase the risk of breast cancer can be passed from parents to children. The most common gene mutations are referred to as BRCA1 and BRCA2. These genes can greatly increase your risk of breast cancer and other cancers, but they don't make cancer inevitable.
- Radiation exposure. If you received radiation treatments to your chest as a child or young adult, you're more likely to develop breast cancer later in life.
- Obesity. Being overweight or obese increases your risk of breast cancer because fat tissue produces estrogen that may help fuel certain cancers.
- Beginning your period at a younger age. Beginning your period before age 12 increases your risk of breast cancer.
- Beginning menopause at an older age. If you began menopause after age 55, you're more likely to develop breast cancer.
- Having your first child at an older age. Women who give birth to their first child after age 35 may have an increased risk of breast cancer.
- Postmenopausal hormone therapy. Women who take hormone therapy medications that combine estrogen and progesterone to treat the signs and symptoms of menopause have an increased risk of breast cancer.
- Drinking alcohol. Drinking alcohol increases the risk of breast cancer. Experts recommend no more than one alcoholic beverage a day for women.
Other risk factors that have been suggested, but don't play any role in the development of breast cancer include tightfitting bras, antiperspirants, breast implants and shift work.
- Breast cancer. American Cancer Society. http://www.cancer.org/acs/groups/cid/documents/webcontent/003090-pdf.pdf. Accessed March 17, 2011.
- What you need to know about breast cancer. National Cancer Institute. http://www.cancer.gov/cancertopics/wyntk/breast/AllPages/Print. Accessed March 19, 2011.
- Chlewbowski RT, et al. Estrogen plus progestin and breast cancer incidence and mortality in postmenopausal women. Journal of the American Medical Association. 2010;304:1684.
- Giuliano AE, et al. Axillary dissection vs. no axillary dissection in women with invasive breast cancer and sentinel node metastasis. Journal of the American Medical Association. 2011;305:569.
- Van Wely BJ, et al. Systematic review of the effect of external beam radiation therapy to the breast on axillary recurrence after negative sentinel lymph node biopsy. British Journal of Surgery. 2011;98:326.
- Robert NJ, et al. RIBBON-1: Randomized, double-blind, placebo-controlled, phase III trial of chemotherapy with or without bevacizumab for first-line treatment of human epidermal growth factor receptor 2-negative, locally recurrent or metastatic breast cancer. Journal of Clinical Oncology. In Press. Accessed March 22, 2011.
- Burstein HJ. Bevacizumab for advanced breast cancer: All tied up with a RIBBON? Journal of Clinical Oncology. In Press. Accessed March 22, 2011.
- Choueiri TK, et al. Congestive heart failure risk in patients with breast cancer treated with bevacizumab. Journal of Clinical Oncology. 2011;29:632.
- Petrelli F, et al. Bevacizumab in advanced breast cancer: An opportunity as second-line therapy? Medical Oncology. In Press. Accessed March 22, 2011.
- Gnant M, et al. Endocrine therapy plus zoledronic acid in premenopausal breast cancer. The New England Journal of Medicine. 2009;360:679.
- Coleman R, et al. Zoledronic acid use in cancer patients. Cancer. 2011;117:11.
- Pruthi S (expert opinion). Mayo Clinic, Rochester, Minn. March 22, 2011.
- Unexpected AZURE results lead to rethink for Zometa. Expert Review of Anticancer Therapy. 2011;11:329.
- Moynihan TJ (expert opinion). Mayo Clinic, Rochester, Minn. April 3, 2011.
- FDA commissioner removes breast cancer indication from Avastin label. Food and Drug Administration. http://www.fda.gov/NewsEvents/Newsroom/ucm279485.htm. Accessed Nov. 18, 2011.


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