How does oncologists decide the cancer stage?

Oncologists use a variety of methods to determine the stage of cancer, including imaging tests and biopsies. Imaging tests, such as X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and positron emission tomography (PET) scans provide detailed images of the bodily areas where cancer may be present. These can help to reveal if the cancer has spread from its original site and if it has spread to other part of the body. Biopsies are used to confirm whether or not cells are actually cancerous. In this test, a tissue sample is taken from the specific area at which abnormal cells have been identified and examined under a microscope for any signs of malignancy.

In addition to visual or physical examinations on tumor size and location that can clue medical professionals into how advanced the cancer may be in different patient cases; doctors also rely upon staging systems created by health organizations like The National Comprehensive Cancer Network (NCCN). These systems evaluate data collected during exams on physical characteristics like lymph node involvement or metastasis as well as laboratory tests results such as blood counts and diagnostic scans in order to classify cancers according stages I – IV with IV indicating more advanced systemic conditions compared with earlier stages that often involve smaller localized tumors. After staging is complete, treatment plans will then proceed accordingly depending upon which stage was assigned by physicians based on their analysis.