Free
E-newsletter
Subscribe to Housecall
Our weekly general interest
e-newsletter keeps you up to date
on a wide variety of health topics.
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Causes
By Mayo Clinic staff
It's not clear what causes breast cancer. Doctors know that breast cancer occurs when some breast cells begin growing abnormally. These cells divide more rapidly than healthy cells do. The accumulating cells form a tumor that may spread (metastasize) through your breast, to your lymph nodes or to other parts of your body.
Breast cancer most often begins with cells in the milk-producing ducts. Doctors call this type of breast cancer invasive ductal carcinoma. Breast cancer may also begin in the milk glands known as lobules (invasive lobular carcinoma) within the breast.
Researchers have identified things that can increase your risk of breast cancer. But it's not clear why some people who have no risk factors develop cancer, yet other people with risk factors never do. It's likely that breast cancer is caused by a complex interaction of your genetic makeup and your environment.
Inherited breast cancer
Doctors estimate that only 5 to 10 percent of breast cancers are linked to gene mutations passed through generations of a family. A number of inherited defective genes that can increase the likelihood of breast cancer have been identified. The most common are breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2), both of which increase the risk of both breast and ovarian cancer.
If you have a strong family history of breast cancer or other cancers, blood tests may help identify defective BRCA or other genes that are being passed through your family. Consider asking your doctor for a referral to a genetic counselor, who can review your family health history. A genetic counselor can also discuss the benefits, risks and limitations of genetic testing with you. It's important to remember that the genetic tests help to identify a high-risk individual or family, but they don't definitively predict who will or will not get breast cancer.
- 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.
Find Mayo Clinic on