Tumor Size
Size is used to help determine the stage of the breast cancer but it doesn’t tell the whole story. All of the cancer’s characteristics are important. A small cancer can be aggressive while a larger cancer is not — or it could be the other way around. Size indicates how large across the tumor is at its widest point. Doctors measure cancer in millimeters (1 mm = .04 inch) or centimeters (1 cm = .4 inch).