The TNM system is a standard system for describing the extent of a cancer’s growth. This system was developed by the American Joint Committee on Cancer and the International Union Against Cancer. It is the most common system used to stage anal cancer. Here’s what the letters stand for in the TNM system:
T (tumor) refers to the size of the tumor in the anus and whether or not it has invaded nearby organs.
N (node) refers to whether the lymph nodes in the area of the anus have become cancerous.
M (metastasis) refers to whether the cancer has spread to other, distant organs in the body, such as your bones, liver, or lungs.
Once your T, N, and M stages have been determined, this information is put together in what is called stage grouping. This is used to determine your overall disease stage. Stage grouping uses Roman numerals going from 0 (the earliest stage) to IV (the most advanced stage):
Stage 0. The cancer is only found in the top layer of anal tissue.
Stage I. The cancer has spread beyond the top layer of anal tissue, but is less than 2 centimeters (about 1 inch) in diameter and has not spread to lymph nodes or other organs.
Stage II. The cancer is more than 2 centimeters in diameter, but it has still not spread to nearby organs or lymph nodes.
Stage III. The cancer has spread to lymph nodes in the rectum, groin, or abdomen, or to nearby organs, such as the vagina or bladder.
Stage IV. The cancer has spread to distant organs in other parts of the body.