Usually, the first diagnosis is made by a specialist caring for the part of the body where cancer originates from. For example, a dermatologist might diagnose skin cancer while an internal medicine specialist might diagnose cancers of the blood cells such as leukemias. When cancer is suspected, a biopsy is often obtained from the suspicious tissue and a pathologist examines the tissue under a microscope. After the diagnosis is made, the patient is referred to an oncology specialist for further assessment and treatment.
The oncologist conducts some tests to determine the extent of the disease. Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) scans are used to see the degree of local extension of cancer. A Positron Emission Tomography (PET) scan is used to screen the whole body for any metastases. Your oncologist may also order some blood tests such as tumor markers to gather additional information about the type of cancer and decide on a treatment plan.