Breast cancer. Coloured profile X-ray of the left breast of a 65 year old woman with breast cancer. There is a malignant (cancerous) tumour (purple) at upper right. Breast cancer is the most common type of cancer in women. The cancer can invade surrounding tissue and spread to other parts of the body (metastasis). Treatment is with removal of the tumour only, where possible, or complete removal of the breast. Surgery is often combined with radiation therapy and chemotherapy.