Any suspicious mass of tissue or tumor is subject to a biopsy, or removal of cells from the mass. This is the only technique that can confirm the presence of cancer cells. The doctor will use a general or local anesthetic depending on the location of the mass, and then remove a sample of tissue to send to the lab. The sample is sent to a pathologist, a physician who is an expert at identifying diseased cells in tissue samples. Very often, a few stiches are used to help the area heal, and tenderness is felt for a short period of time.