A woman's lifetime risk of gettingbreast cancer is about 1 in 250 at age 35, but rises to about 1 in 50 by age 65.Breast cancer diagnosis has increased steadily in the United States since themid-1980s, but the death rate from breast cancer has also fallen steadily duringthe same period. Breast cancer occurs in men as well as women, but is much less common. Boththe behavior of the disease and its treatment are similar to that in women. The exact way that breast cancer develops is not well understood. This is currently a major area of research.
Several factors affect a woman's chance of developing breast cancer.
Between 5 and10 percent of invasive breast cancer is related to the presenceof a gene that confers a very high risk of developing the disease. Both BRCA1 and BRCA2 also carry an increased risk of ovariancancer and some other malignancies. Only by doing a breast biopsy can a reliable diagnosis of breast cancer bemade. The diagnosis can be inferred from thepresence of a lump in the breast or from a suspicious finding on a mammogram,but a confirmed diagnosis can be made only by a biopsy. Benign breast diseasemay also produce breast lumps.