Breast cancer, sagittal section. Sequence of magnetic resonance imaging MRI scans showing a malignant cancerous tumour bright 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 surgery to prevent the tumour from regrowing.