The ten-year survival rate with appropriatetreatment is 99 percent. Treatment is ordinarilydirected at the diseased breast and at the cancer cells that may have spreadbeyond the breast. Aside from skin and lung cancer, breast cancer is the most common type ofcancer seen in women in the United States and in other western societies. Thefrequency of the disease rises with age. 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.