Oncology is a branch of medicine that deals with treatment of tumors. A medical professional who practices oncology is an oncologist. The responsibility of an oncologist is to diagnose, educate and treat patients that are dealing with cancer. The three major areas in the discipline of oncology are Surgical, Medical and Radiation. Medical Oncologists skillful in treatment that uses chemotherapy drugs to kill cancer cells and condense the size of tumors. Surgical Oncologists specialize on using surgery to eradicate cancerous tumors and often a margin of healthy tissue surrounding the tumor. Radiation Oncologists expert in treating cancer with radiation therapy, which kill cancer cells using various radiotherapy machines. The other types of oncologists include gynecologic oncologists, pediatric oncologists and hematologist/oncologist. Gynecologic Oncologists focus on treating women with cancers such as uterine or cervical cancer. Pediatric Oncologists cure children with cancer usually under the age of 18. A Hematologist Oncologist is a doctor who treats blood cancer such as leukemia.