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Anal cancer

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Staging anal cancer

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. Extent includes the size of the tumour and where the cancer is in the body. Your healthcare team uses the stage to plan treatment and estimate your prognosis.

The most common staging system for anal cancer is the TNM system. Each stage is given a number from 0 to 4. Stages 1 to 4 are usually given as the Roman numerals I, II, III and IV. Generally, the higher the number, the more the cancer has spread.

Doctors often stage perianal skin cancer differently than other anal cancers. It is staged like cancer from another area of the skin.

When describing the stage, doctors may use the terms local, regional and distant. Local means that the cancer is only in the anus and has not spread to other parts of the body. Regional means close to or around the anus. Distant means in a part of the body farther from the anus.

TNM descriptions

T describes the size of the primary tumour and if the cancer has spread to organs close to the anus. T is usually given as a number from 1 to 4. A higher number means that the tumour is larger, the cancer has spread to nearby organs or both.

N describes the spread of cancer to lymph nodes around the anus, including lymph nodes in the groin and pelvis. N0 means the cancer hasn’t spread to the lymph nodes. N1, N2 or N3 means cancer has spread to lymph nodes. N1 to N3 also describe the location of lymph nodes that contain cancer.

M describes whether or not the cancer has spread, or metastasized, to other parts of the body. M0 means that cancer has not spread to other parts of the body farther from the anus. M1 means that it has spread to other parts of the body farther from the anus.

Stage 0 (or carcinoma in situ)

TNMDescription

Tis

N0

M0

The cancer is carcinoma in situ. This means that the tumour or abnormal cells are only in the top layer of anal tissue. Stage 0 includes high-grade anal intraepithelial neoplasia (AIN) and Bowen’s diseaseBowen’s diseaseA condition that affects the skin. Signs include red, crusty sores or scaly patches on the skin that grow slowly and do not heal. It is an early stage of skin cancer (carcinoma in situ). of the anus.

Stage I

TNMDescription

T1

N0

M0

The tumour is 2 cm or smaller.

Stage II

TNMDescription

T2 or T3

N0

M0

The tumour is larger than 2 cm.

Stage IIIA

TNMDescription

T1, T2 or T3

N1

M0

The tumour is any size.

The cancer has spread to lymph nodes around the rectum.

T4

N0

M0

The tumour is any size. The cancer has spread to nearby organs such as the bladder, urethra or vagina (in women).

Stage IIIB

TNMDescription

T4

N1

M0

The tumour can be any size. The cancer has spread to nearby organs such as the bladder, urethra or vagina (in women).

The cancer has spread to lymph nodes around the rectum.

any T

N2 or N3

M0

The tumour can be any size. The cancer may have spread to nearby organs such as the bladder, urethra or vagina (in women).

One of the following applies:

  • The cancer has spread to lymph nodes on one side of the groin, one side of the pelvis or both.
  • The cancer has spread to lymph nodes around the rectum and in the groin, lymph nodes on both sides of the pelvis, lymph nodes on both sides of the groin or lymph nodes in more than one of these areas.

Stage IV

TNMDescription

any T

any N

M1

The tumour is any size. The cancer may have spread to nearby organs such as the bladder, urethra or vagina (in women).

The cancer may have spread to lymph nodes around the rectum, in the groin, in the pelvis or in more than one of these areas.

The cancer has spread to other parts of the body farther from the anus (called distant metastasis).

Recurrent anal cancer

Recurrent anal cancer means that the cancer has come back after it has been treated. If it comes back in the same place that the cancer first started, it’s called local recurrence. If it comes back in tissues or lymph nodes close to the primary tumour, it’s called regional recurrence. It can also recur in another part of the body, which is called distant metastasis, or distant recurrence.

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