Breast cancer is the most common type of cancer diagnosed in women if the relatively less aggressive skin cancer is excluded from counting. Breast cancer accounts for about 32 percent of all cancer diagnosed in women.

Breast cancer is very uncommon in male. In families carrying the breast cancer associated genes, male members may be affected disproportionately compared to the general population. In the general population female to male breast cancer may occur at a rate of 1 to 100 (1:100 for male: female).

Prior to introduction of mammography screening breast cancer was often diagnosed as a large lump in the breast, because women were not paying attention to the development of breast tumors. Introduction of mammography had significantly changed the natural history breast caner. In industrialized nations like the United States breast caner is most commonly detected on mammography screening. Mammography screening also brought a great sense of awareness to women and this has resulted in earlier detection of breast cancer.

Even if a woman does not get mammography screening, they are very much aware of the risk of development of breast cancer and thus tend to observe and even examine their breasts. Most women do self-breast examination in between mammograms. Because of this increased awareness, women presenting with locally advanced breast cancer are quite rare in the industrialized nations.

In some women breast cancer may have spread to distant organs, before mammography screening or symptoms showed the breast cancer. This can happen because early stage breast cancer does not usually cause any symptoms. If the cancer has spread to other organs these women may present with symptoms related to these organs. For example if the cancer has spread to the bone the woman may develop bone pain or bone fracture.

Diagnosis of breast cancer involves a biopsy procedure. Most often an abnormality in the mammogram leads to a biopsy, many other times, the woman may have felt a lump in the breast or the physician examining the patient may have felt a lump in the breast.

Biopsy is the procedure by which a small part of the breast tissue is removed and examined under the microscope. A typical beast cancer would show classic features of breast cancer. Sometimes the abnormality may be a non-invasive breast cancer or so called carcinoma in situ.