Breast cancer. Conceptual image of a coloured mammogram (breast X-ray, blue), clock faces and a cancer cell (white, centre) over a woman's breast. These all represent various aspects of breast cancer, the most common cancer in women. Cancer is the abnormal and uncontrolled division of cells, resulting in the invasion and destruction of surrounding body tissues. Symptoms of breast cancer include painless lumps appearing in the breast, a dark discharge from the nipple, and an indentation of the nipple. The clock faces may represent the need for early diagnosis by breast X-rays and regular self-examination. Such cancers can be treated by surgery, radiotherapy and drugs.