Oncology is the branch of medicine concerned with the treatment of cancer. Cancer is the uncontrolled growth of abnormal cells in the body. There are hundreds of types of cancer, commonly named according to the organ or tissue where the cancer develops.  There are an estimated 1.7 million new cases of cancer in the United States in 2012. The most common are lung cancer, colon cancer, prostate cancer and breast cancer. Cancer can also spread or metastasize to other areas of the body.