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The female breast consists of milk-producing glands (the lobes and smaller lobules), ducts that conduct milk to the nipple, connective tissues, blood vessels, and lymph vessels that conduct lymph to lymph nodes in the axilla (armpit). Breast cancer occurs when breast cells do not die when they would under normal circumstances or when breast cells reproduce more rapidly than normal, forming a tumor. Breast tumors can develop in any of the breast tissues but are most common in the cells lining the ducts. Not all breast tumors are malignant (cancerous).
There are several risk factors that contribute to breast cancer. A woman's risk for breast cancer increases as she ages. Most new diagnoses are in women age 60 and older. Family and personal history of cancer, especially breast cancer, increase the risk of breast cancer. Certain lifestyle factors also increase breast cancer risk. These include alcohol consumption, obesity (especially after menopause), and physical activity.
The early stages of breast cancer typically show no symptoms. However, as the cancer progresses, some symptoms may be noticed. These can include
Breast cancer is typically detected through clinical breast exams (CBEs) or mammograms, which can be performed as preventative measures before any symptoms are noticed by a woman. During a CBE, a healthcare provider will examine the breast and nipples, palpating the breast tissue (which extends to the collarbone and underarms) and checking for lumps. A mammogram is an x-ray image taken of the breast. A mammogram can show breast lumps and calcium deposits in the breast that cannot be felt. The National Cancer Institute recommends that women should have a mammogram every one to two years beginning at age 40.
If a provider finds something abnormal during a CBE or mammogram, additional testing may be required. This can include breast ultrasounds, MRIs, and biopsies with subsequent tissue tests in the lab.
The National Cancer Institute estimates that 210,000 Americans will be diagnosed with breast cancer in 2010. Breast cancer will cause approximately 40,000 during the same year.
For more information about breast cancer, detection, diagnosis, and treatment, we suggest
All information is from the National Cancer Institute and American Cancer Society.
Updated July 2010.