Oncology is the study and treatment of cancer and tumors. An oncologist is a physician who diagnoses and treats cancer patients. The oncologist sometimes uses chemotherapy, and consults with other physicians to coordinate other methods of cancer treatments for a patient. Cancer patients need to take in to account the likelihood of a cure, or of prolonging life when cure is not possible, the effect of treatment on their symptoms, and the side effects of the treatment. People who are candidates for radiation therapy or anti-cancer drugs need to understand the risks involved with treatment. An oncologist can help to counsel a patient on treatment options and what to expect.

Physicians in this specialty treat patients suffering from numerous diseases and illnesses, but some of the most common are breast disease, Hodgkin's disease, colon cancer, Bone Marrow, Melanoma, breast cancer, Spinal Cord Tumors, Skin Cancer, Leukemia, lymphoma, lung cancer, Cervical cancer, Mesothelioma, Pancreatic cancer, Sarcoma, Oral cancer, Renal cell carcinoma, Thyroid cancer, Liver cancer, and bone cancer.

Once properly diagnosed, practitioners can perform numerous procedures on patients including breast surgery, Cryotherapy, Brachytherapy, breast reconstruction, CABG, Colonoscopy, cryosurgery, mastectomy, Chemotherapy, surgery, radiotherapy, adjuvant therapy, Bone marrow transplantation (BMT), immunotherapies, External Beam Radiotherapy, monoclonal antibody treatments, and Hormone manipulation.

To diagnose patients with possible illnesses and diseases, specialists will often perform one of many tests including biopsy, CT scanning, Beta- HCG, MRI scanning, Magnetic Resonance Imaging (MRI), X-rays, ultrasound, Computed Axial Tomography (CT or CAT Scan), CEA, endoscopy, NSE, Blood tests, CA 125, Tumor markers, Positron emission tomography, Scintigraphy, Beta HCG, PSA, and Alpha fetoprotein.