The disease is most commonly diagnosed in women over age 50. Very few women under age 30 develop it. Despite the rise in incidence, there has been a small drop in the number of deaths in the recent years and only about one-fifth of cases prove fatal. This reduction is due to improvements in treatment and the increased use of mammography for screening, which means that tumors can be detected early, when they often respond well to treatment.
Screening may reduce the number of deaths in women over age 50 by up to 4 in 10. In the US, many doctors recommend that women over age 40 have a mammogram every 1-2 years and every year over age 50. A cancerous tumor may first develop in the breast lobules (the structures in the breast that produce milk). A tumor that originates in the milk ducts may lead to Paget's disease of the breast. Tumors may spread to other organs, such as the lungs or the liver, before being detected.
It is a cancer that originates in the breast tissue of women and men. It can spread to the lymph nodes under the arm before diagnosis. With advanced disease, metastasis can be seen in many body organs, including bone, brain, lung, liver and skin.
It is usually manifest as a painless lump anywhere in the breast or under the arm. Occasionally, its symptoms can be more subtle, such as: