Tthe process of finding out whether cancer has spread and if so, how far; the process of learning the stage of the cancer.
There is more than one system for staging different types of cancer. The TNM staging system, which is used most often, gives 3 key pieces of information:
T refers to the size of the tumor
N describes whether the cancer has spread to nearby lymph nodes, and if so, how many
M shows whether the cancer has spread (metastasized) to other organs of the body

Letters or numbers after the T, N, and M give more details about each of these factors. To make this information clearer, the TNM descriptions can be grouped together into a simpler set of stages, labeled with Roman numerals (usually from I to IV). In general, the lower the number, the less the cancer has spread. A higher number means a more serious cancer.

The 2 main types of staging are clinical and pathologic.
- clinical staging is an estimate of the extent of cancer based on physical exam, biopsy results, and imaging tests.
- pathologic staging is an estimate of the extent of cancer by studying the samples removed during surgery.

American Cancer Society. Glossary. Internet. Accessed September 3, 2017.