Overview

What is cancer?

Cancer is the uncontrolled growth of cells in an organ (such as the breast, cervix, ovary or lung). Cancer cells grow together to form a mass called a tumor. Cancer is life threatening because cancer cells can invade surrounding tissue and spread through the bloodstream or lymphatic system to distant parts of the body (metastasize). Early detection before the cancer spreads provides the best chance of cure.

What is breast cancer?

Breast cancer is the most common type of cancer in women. Men can also develop breast cancer, but it is rare, accounting for less than 1 percent of all cases. Breast tumors, both benign and malignant, can develop in any part of the breast. Most tumors, however, arise from ducts that carry milk from the lobule, where milk is produced, to the nipple. About one in seven adult women in the United States develop breast cancer. If detected at an early stage when the tumor has not spread to lymph nodes, most women, about 97 percent, are cured. Early detection of breast cancer is due mainly to annual mammography screening and physical breast examinations.

More on Breast Cancer

In the Encyclopedia:

This article was reviewed and updated June 2007.