Anal cancer is a Cancer that forms in tissues of the anus. Anus is the opening of the rectum (last part of the large intestine) to the outside of the body.

A cancer stage tells the doctor how far the cancer has grown or spread. The stage of a cancer describes where the cancer is located, if or where it has spread, and whether it is affecting the functions of other organs in the body.  This information is used by the doctor to decide on the most suitable treatment for the patient.

TNM system is used to describe about the stage of the cancer. The following factors are used to tell stage of the cancer:

  • The size of the primary tumor (Tumor, T)
  • Whether the tumor spread to the lymph nodes (Node, N)
  • Whether the cancer metastasized to other parts of the body (Metastasis, M)


The size of Tumor (T) –

The stages are:

TX: The primary tumor cannot be evaluated.

T0: There is no tumor.

Tis: Carcinoma in situ is present.

T1: The tumor is no larger than 2 cm

T2: The tumor is larger than 2 cm but not larger than 5 cm

T3: The tumor is larger than 5 cm

T4: The tumor has invaded other organs, such as the urethra, bladder, or a woman’s vagina.

N stages of Anal Cancer

N0:  no lymph nodes contain cancer cells

N1: there are cancer cells in the lymph nodes closest to the rectum

N2: Cancer cells are spread to the internal iliac (pelvic) and/or the inguinal (groin) lymph nodes on the same side of the body.

N3: nodes in the pelvis or groin on both sides of the body contain cancer cells

M stages of Anal Cancer-

M0: no cancer spread to other organs

M1: cancer has spread to another part of the body, such as the liver.

Number stages of anal cancer


The stage of anal cancer is assigned by combining the T, N, and M classifications.

Stage 0: Here, abnormal cells are contained within the lining of the anus. These cells may develop into cancer if left untreated.

Stage I: In this stage, the tumor is no larger than 2 cm. It has not spread to the lymph nodes or other parts of the body (T1, N0, and M0).

Stage II: Here, The cancer is larger than 2cm but has not spread anywhere else in the body (T2 or T3, N0, M0).

Stage IIIA: It describes that the cancer is of any size and might have spread into nearby lymph nodes or organs. It is similar to T1 or T2 or T3, N1, M0; or T4, N0, M0

Stage IIIB: In this stage, the cancer is of any size and has spread to the lymph nodes and may also have grown into nearby organs same as T4, N1, M0; or any T, N2 or N3, M0.

Stage IV: This stage tells that cancer is of any size and has spread to other parts of the body such as the liver. It is same as any T, any N, and M1.