Oncology is the branch of medicinal science that diagnoses, identifies and treats cancer. A physician who works within the field of oncology is an oncologist. Oncologists should first diagnose a cancer that is via diagnostic test, endoscopy, X-ray, CT scanning, MRI, PET scanning, ultrasound or alternative radiological methods. Medical specialty can even be used to diagnose cancer, as will blood tests or tumor markers. Oncology connected with haematology that is the branch of medicine that deals with blood and related disorders.