Breast cancer starts when cells in the breast begin to grow out of control. These cells usually form a tumor that can often be seen on an x-ray or felt as a lump. The tumor is malignant (cancer) if the cells can grow into (invade) surrounding tissues or spread (metastasize) to distant areas of the body. Surgery is usually the first type of treatment for breast cancer. The type of surgery you undergo will depend on the type of breast cancer you have. Surgery is usually followed by chemotherapy or radiotherapy or, in some cases, hormone or biological treatments. Again, the treatment you’ll have will depend on the type of breast cancer. We discuss the most suitable treatment plan with you. Chemotherapy or hormone therapy will sometimes be the first treatment.