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Breast Cancer Basics

About Breast Cancer

Of all cancer diseases, breast cancer is the most common among women: One in eight will be affected by it in their lifetime.

The American Cancer Society estimates that 192,370 American women were newly diagnosed with invasive breast cancer in 2009. Breast cancer also occurs in men; however, it is much less common among males, with 1,910 estimated as newly diagnosed in 2009.

Breast cancer can be invasive (invasive lobular carcinoma) or non-invasive (ductal carcinoma in situ). Invasive breast cancer occurs when the cancer cells within the breast's lobules or milk producing glands break free and move into the nearby breast tissue and, in some cases, spread farther. Non-invasive breast cancer occurs when the cancer cells remain in place in the milk ducts. ("In situ" means "in place.")

The cause of breast cancer is not known; however, some breast cancers are inherited, passed down through generations of a family. The most common breast cancer genes that increase the risk of breast cancer are BRCA1 and BRCA2.

Learn more about this cancer