Cancer is potentially curable if diagnosed and treated in early stages. Even in late stages where cure may not be possible patient can be treated to have meaningful life with disease. Correct diagnosis and management is of paramount importance. Oncologists can literally be referred to as cancer fighters, they help in diagnosis of the cancer, help in staging the cancer and grading the aggressive nature of the cancer. The most important diagnostic tool remains the clinical history of the patient. Common symptoms that point towards cancer include fatigue, weight loss, unexplained anemia, fever of unknown origin etc. Oncology depends on diagnostic tools like biopsy or removal of bits of the tumour tissue and examining it under the microscope. Other diagnostic tools include endoscopy for the gastrointestinal tract, imaging studies like X-rays, CT scanning, MRI scanning, ultrasound and other radiological techniques..