Stages of Anal Cancer


If your care team diagnoses you with anal cancer, the next critical step is figuring out the stage of the cancer, or how advanced it is. To do this, we may recommend CT and MRI scans to see if the cancer has spread. Staging helps our experts design a plan that treats your anal cancer in the most effective way possible.

Our doctors use the American Joint Committee on Cancer TNM system to determine how advanced a tumor is. We will tell you the stage of the disease by using a combination of the numbers and letters below. We will carefully explain exactly what they mean when we tell you the stage. Regardless of the stage of the cancer, MSK has options that can help you.

TNM System

Your doctor will use a combination of letters and numbers to help describe the stage of the cancer:

  • T is the size of the tumor.
  • N is whether the cancer has spread to the lymph nodes.
  • M is whether the cancer has metastasized (spread) to other parts of the body.

Anal cancer is categorized into five stages:

  • Stage 0 is very early cancer that is found only in the top layer of the lining of the anus.
  • Stage I tumors are small (less than two centimeters, or smaller than the size of a peanut) and have grown deeper into the lining of the anus. The cancer has not spread outside the anus.
  • Stage II cancer means the tumor is larger than two centimeters but has not spread.
  • Stage III cancer has spread to nearby lymph nodes.
  • Stage IV cancer has spread to nearby lymph nodes and other parts of the body.

If anal cancer has spread to other parts of your body, your MSK doctor may talk with you about having the tumor analyzed by MSK-IMPACT™. This highly advanced technology was developed at MSK. The test provides a tremendous amount of information about the genetic makeup of a tumor. Your doctor may use these details to help find a clinical trial matched to your tumor.

Learn more about how MSK-IMPACT works