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Anus

This information should not be used for self-diagnosis or in place of a qualified physician's care.

Reviewed March 2016

The basics
  • Guidelines for treating anal cancer have been developed by the Gastrointestinal (GI) Tumour Group.
  • For health professional information on treating this cancer, please see our Cancer Management Guidelines (Anus).
  • The anus or anal canal is the tube that connects the rectum to the outside of the body.
  • Anal cancer is not common. There are about 600 cases in Canada each year.
  • The incidence of anal cancer is rising for women. [See note, Statistics]
  • Anal cancer can be cured in most cases.

What causes it and who gets it?

Some of the known risk factors for anal cancer are listed below. Not all of the risk factors below may cause this cancer, but they may be contributing factors.

  • The cause of anal cancer is unknown.
  • The following contributing factors are recognized:
    • HPV infections (human papillomavirus) 
    • Anal sex
    • Having many sexual partners
    • HIV (human immunodeficiency virus) infections
    • Bowen's disease, a skin condition (a rough, scaly patch) that can occur in the skin around the anus. It can become cancer if left untreated.
    • Smoking
  • Statistics
    • BC  - 2012 Statistics 
    • 107 new cases diagnosed
    • Canada

Can I help to prevent it?

  • Routine sexual health screening is recommended for all sexually active adults.
  • It's best to get immunized against HPV (human papillomavirus) before becoming sexually active; however, people who are sexually active may still benefit from vaccination. Detailed information is available on the Immunize BC website.
  • Practice safer sex by using a new condom every time you have vaginal, anal or oral sex. 
  • To reduce your risk, don’t smoke, and avoid exposure to tobacco and cigarette smoke. Even if you have been using tobacco for many years, quitting will reduce your cancer risk. Support is available to help you successfully quit. Visit the BC Cancer Agency’s Prevention page on Tobacco for information and resources.

Screening for anal cancer

  • The anal canal should be examined by digital rectal examination (DRE) during a yearly physical exam.
  • People at higher risk for anal cancer may benefit from a test of cells scraped from the anus.

Signs and Symptoms

  • In the earlier stages, there may be no symptoms.
  • The following symptoms should be checked by your doctor:
    • Bleeding from the anus may be the first sign
    • Anal itching that won't go away
    • Discharge of mucus from the anus
    • A change in bowel movements
    • A sore that is on or near the anus
    • Swollen lymph nodes in the groin or anal region

NOTE:  Available statistics do not have information about the inclusion of transgender and gender diverse participants. It is unknown how these statistics apply to transgender and gender diverse people.  Patients are advised to speak with their primary care provider or specialists about their individual considerations and recommendations.
Diagnosis & staging

Diagnosis

These are tests that may be used to diagnose anal cancer.

  • Physical examination
  • Digital rectal examination (DRE)
  • Anoscopy or sigmoidoscopy, which is the insertion of a tube into the anus with a light to allow viewing of the interior of the anal canal.
  • Biopsy of anal tissue – a small bit of the suspicious tissue is removed and examined by a pathologist.
  • A gynecological exam with pap smear for patients with a vagina to check for cervical cancer, as both types of cancer are related to HPV (human papilloma virus).
  • If lymph nodes are swollen, it may be possible to test for the presence of cancer cells.
  • If cancer is found, further tests are done to determine if it has spread. These include a CT scan of the abdomen and pelvis, an ultrasound to examine the liver and an MRI to assess the pelvis.
For more information on tests used to diagnose cancer, see our Recommended Websites, Diagnostic Tests section.

Types and Stages

Types
  • Almost all anal cancers are squamous cell carcinomas, which start in the cells that line the anus.
  • The rest are cloacogenic (basaloid transitional).
  • Adenocarcinomas are the rarest and develop in anal ducts and glands.
  • Very rarely, basal cell carcinomas and melanomas develop in the anus.
Stages
Stage describes the extent of a cancer. The TNM classification system is used as the standard around the world. In general a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment.
  • T describes the site and size of the main tumour (primary)
  • N describes involvement of lymph nodes
  • M relates to whether the cancer has spread (presence or absence of distant metastases)
  • T is Carcinoma in situ.
  • T1 Tumour is 2 cm or less
  • T2 Tumour is 2 cm - 5 cm in size
  • T3 Tumour is more than 5 cm in size
  • T4 Tumour of any size spreads to adjacent organ(s), e.g. vagina, urethra, bladder
Treatment

Treatment

Cancer therapies can be highly individualized – your treatment may differ from what is described below.

  • If the tumour is small and the sphincter is not involved, surgery is used to remove it completely. The function of the anus and bowel should not be affected.
  • If the tumour is small, but the sphincter is involved, radiation therapy may be used alone or in combination with chemotherapy.
  • For larger anal cancers, a combination of chemotherapy and radiation therapy offers a good chance of curing the cancer. Side effects from this treatment are more severe. The treatment aims to maintain the patient's ability to have normal bowel movements.
  • For the largest anal cancers, or those which do not respond to treatment, or if the cancer comes back after treatment, it may be necessary to remove the entire rectum and the patient will have a permanent colostomy and wear an external device to collect feces.

Follow-up after Treatment

  • Guidelines for follow-up after treatment are covered on our website.
  • You will be returned to the care of your family doctor or specialist for regular follow-up. If you do not have a family doctor, please discuss this with your BC Cancer oncologist or nurse.
  • Follow-up testing is based on your type of cancer and your individual circumstances.
  • Life after Cancer focuses on the issues that cancer survivors can face.
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SOURCE: Anus ( )
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