Breast cancer. Coloured scanning electron micrograph (SEM) of freeze-fractured tissue from a breast tumour. A group of glandular epithelial cells (around centre) form a secretory structure called an acinus. The cells secrete components of the milk that flows along the duct (central hole) into larger ducts, and eventually reaches the nipple. Most breast cancers arise as carcinomas of ductal epithelial tissue. Breast cancer, the most common cancer in women, can be treated by surgical removal, often combined with radiotherapy and chemotherapy. Magnification: x2000 at 6x7cm size.