Anal Cancer Stages

After someone is diagnosed with anal cancer, 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.

The earliest stage anal cancers are called stage 0, and then range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage. 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 for anal cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:

  • The extent (size) of the tumor (T): What is the size of the cancer? 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 liver or lungs?

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 information see Cancer Staging.

Anal cancer is usually staged based on the results of a physical exam, biopsy, and imaging tests. This is called a clinical stage. If surgery is done, the pathologic stage (also called the surgical stage) is determined by examining tissue removed during an operation. This is also known as surgical staging.

The system described below is the most recent AJCC system effective January 2018. It is used for tumors in the anal canal and perianal (formally anal margin) area.

Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.

 

AJCC Stage

Stage grouping

Stage description*

0

 

Tis

N0

M0

The cancer is only in the mucosa (the top layer of cells lining the inside of the anus). It has not started growing into the deeper layers. (Tis). It has not spread to nearby lymph nodes (N0) or distant sites (M0).

I

          T1

N0

M0

The cancer is 2 cm (about 4/5 inch) across or smaller (T1). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

IIA

          T2

N0

M0

The cancer is more than 2 cm (4/5 inch) but not more than 5 cm (about 2 inches) across (T2). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

IIB

T3

N0

M0

The cancer is larger than 5 cm (about 2 inches) across (T3). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

 

IIIA

 

 

T1

N1

M0

The cancer is 2 cm (about 4/5 inch) across or smaller (T1) AND it has spread to lymph nodes near the rectum (N1) but not to distant sites (M0).

OR

T2

N1

M0

The cancer is more than 2 cm (4/5 inch) but not more than 5 cm (about 2 inches) across (T2) AND it has spread to lymph nodes near the rectum.

(N1) but not to distant sites (M0).

IIIB

T4

N0

M0

The cancer is any size and is growing into nearby organ(s), such as the vagina, urethra (the tube that carries urine out of the bladder), prostate gland, or bladder (T4). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

IIIC

T3

N1

M0

The cancer is larger than 5 cm (about 2 inches) across (T3) AND it has spread to lymph nodes near the rectum (N1) but not to distant sites (M0).

OR

T4

N1

M0

The cancer is any size and is growing into nearby organ(s), such as the vagina, urethra (the tube that carries urine out of the bladder), prostate gland, or bladder (T4) AND it has spread to lymph nodes near the rectum (N1) but not to distant sites (M0).

IV

Any T

Any N

M1

The cancer can be any size and may or may not have grown into nearby organs (any T). It may or may not have spread to nearby lymph nodes (any N). It has spread to distant organs such as the liver or lungs (M1).

 

*The following additional categories are not listed on the table above:

  • TX: Main tumor cannot be assessed due to lack of information.
  • T0: No evidence of a primary tumor.
  • NX: Regional lymph nodes cannot be assessed due to lack of information. 

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

American Joint Committee on Cancer. Anus. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017: 275.

Last Medical Review: December 8, 2017 Last Revised: December 8, 2017

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