Breast cancer is the most commonly diagnosed form of cancer among women, excluding non-melanoma skin cancers. Breast cancer is the second most deadly form of cancer among women, exceeded only by lung cancer. The survival rate for breast cancer is significantly higher in women who are diagnosed at earlier stages of the disease.
Breast cancer is frequently defined by where it begins in the breast. The most common variety of breast cancer is ductal carcinoma, which begins in the cells that line the milk ducts. Lobular carcinoma begins in the milk glands, or lobes. Less common forms of breast cancer include Paget’s disease of the nipple and inflammatory breast cancer.
Cancer that is confined to either the milk ducts or the milk glands are referred to as being in situ, the Latin for “in the place.” In situ breast cancers are very early stages of the disease. Breast cancer that is discovered while still in situ can almost always be cured, according to the National Cancer Institute. Breast cancer that starts in the milk ducts or milk glands is more likely to be discovered after it has spread to surrounding tissues. This type of cancer is referred to as invasive cancer. The survival rate for women with invasive breast cancer decreases as the disease advances.
Breast cancer is frequently identified by stages, based on criteria established by the reporting agency. The American Joint Committee on Cancer uses Stage I through Stage IV to describe the advanced nature of the cancer, with Stage I being early and Stage IV being advanced. The SEER Summary Stage system uses Local, Regional and Distant stages to describe how far the cancer has spread. In both methods, women whose cancer is discovered at earlier stages, when it is still confined to the breast, have a higher survival rate than those who are diagnosed at later or more advanced stages of the disease.
Women who are diagnosed with breast cancer at its earliest stages have a 93 percent rate of surviving for at least five years, according to the American Cancer Society. The survival rate drops to 81 percent once the disease has progressed to Stage II. If the breast cancer was at Stage III when it was discovered, the survival rate drops to 67 percent. Women with Stage IV breast cancer have a 15 percent survival rate. The American Cancer Society notes that every woman’s situation is different and that new treatments are continuing to improve survival rates among women with breast cancer.
Both the incidence of breast cancer and mortality from breast cancer increase with age, according to the U.S. Centers for Disease Control and Prevention. A 60-year-old woman is more than twice as likely to develop breast cancer within a 10-year period as a 40-year-old woman. White women are more likely to be diagnosed with breast cancer than any other ethnic group in the United States. Black women have a higher mortality rate from breast cancer than any other ethnic group in the U.S.