After a person is diagnosed, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.
Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.
How is the stage determined?
The staging system most often used is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:
- The extent (size) of the main tumor (T): How large has the cancer grown? Has the cancer reached nearby structures or organs?
- The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
- The spread (metastasis) to distant sites (M): Has the cancer spread to distant lymph nodes or distant organs such as the bones, lungs, or peritoneum (the lining of the abdomen )?
Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced.
Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. For more on this, see Cancer Staging.
Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.