Breast cancer, sagittal sections. Coloured sequence of magnetic resonance imaging MRI scans showing a malignant cancerous tumour pink mass of the left breast in a 58_year_old patient. This is an adenocarcinoma. Breast cancer is the most common cancer in women. It can be treated by excision of the tumour if it is caught early. Radiotherapy and chemotherapy are often used, as well as partial or full mastectomy surgery to prevent the tumour from regrowing.