Breast cancer takes years to develop. Early in the disease, most cancers of the breast cause no symptoms. When breast cancer is detected in the localized stage without spread to lymph nodes, the five year survival rate is 97%. If the cancer has spread regionally to axillary (underarm) lymph nodes the rate drops to 76%. If distant metastasis (spread) to other organs such as the lungs, bone marrow, liver, or brain is present, the five year survival rate is 20%.
Screening mammography is an X-ray examination of the breast in a woman who is asymptomatic (has no breast complaints). The goal of screening mammography is to detect cancer when it is still too small to be felt by the patient or by her physician. Early detection of small breast cancers by screening mammography greatly improves a woman's chances for successful treatment.
Screening mammography usually involves two views (X-ray pictures) of each breast. For some patients, additional pictures may be needed at screening to include as much breast tissue as possible.
The American Cancer Society Board of Directors voted on March 23, 1997 to change the Society's breast cancer detection guidelines to include yearly screening mammography for all women 40 years of age and older.