|Breast Cancer Overview| |The Abramson Cancer Center of the
University of Pennsylvania| About Breast Cancer: An Overview
Breast cancer is the most common type of cancer among American
women. Breast cancer is a group of related diseases in which
cells within the breast become abnormal and divide without
control or order. The most common types of breast cancer occur
in the lining of the ducts or in the lobules of the breast. One
in nine women will develop breast cancer in her lifetime.
Approximately 160,000 new cases of breast cancer are diagnosed
each year. Most breast cancer occurs in women over the age of 50
years. With earlier detection methods, breast cancer is now
found at an early stage of development in the majority of women.
All women are at risk for breast cancer. But women with a strong
family history of breast cancer, a personal history of breast
cancer, early first menstruation, late menopause, or first full-
term pregnancy after age 30 are at a higher risk. The risk of
developing breast cancer also