Breast cancer is the most common cancer among American women, except for skin cancers. The chance of developing invasive breast cancer at some time in a woman's life is a little less than 1 in 8 (12%).

The American Cancer Society's most recent estimates for breast cancer in the United States are for 2009:

• about 192,370 new cases of invasive breast cancer will be diagnosed in women

• about 62,280 new cases of carcinoma in situ (CIS) will be diagnosed (CIS is non-invasive and is the earliest form of breast cancer).

• about 40,170 women will die from breast cancer

After increasing for more than 2 decades, female breast cancer incidence rates decreased by about 2% per year from 1999 to 2006. This decrease may be due at least in part to less use of hormone replacement therapy (HRT) after the results of the Women's Health Initiative were published in 2002. This study linked HRT use to an increased risk of breast cancer and heart diseases.

Breast cancer is the second leading cause of cancer death in women, exceeded only by lung cancer. The chance that breast cancer will be responsible for a woman's death is about 1 in 35 (about 3%). Death rates from breast cancer have been declining since about 1990, with larger decreases in women younger than 50. These decreases are believed to be the result of earlier detection through screening and increased awareness, as well as improved treatment.

At this time there are over 2.5 million breast cancer survivors in the United States. (This includes women still being treated and those who have completed treatment.) Survival rates are discussed in the section "How is breast cancer staged?"

Last Medical Review: 09/18/2009
Last Revised: 09/18/2009