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by McCoy K

Anal Cancer

(Cancer of Anus)

Definition

Anal cancer is cancer of the anus. This is the canal at the end of the large intestine, below the rectum. The anal sphincter is a muscular ring that controls and allows for bowel movements.
Treatment for anal cancer depends on how early it is detected, or if the cancer has spread.
The Anus
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Causes

Cancer occurs when cells in the body divide without control or order. Eventually these uncontrolled cells form a growth or tumor. The term cancer refers to malignant growths. These growths can invade nearby tissues and spread to other parts of the body.
There is evidence that human papillomavirus (HPV) infection is linked to many anal cancers. However, most people who have been infected with HPV do not get anal cancer.

Risk Factors

Factors that increase your risk of anal cancer include:

Symptoms

Some anal cancers do not have symptoms. When symptoms do occur, they may include:
  • Anal bleeding with and without a bowel movement
  • Pain or pressure around the anus
  • Itching or discharge from the anus
  • A lump near the anus
  • Change in bowel habits
  • Thinning in the width of the stool

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. Tests can rule out or confirm a cancer diagnosis. Tests may include:
  • Digital rectal examination
  • Anoscopy—exam of the anus and lower rectum
  • Proctoscopy—exam of the rectum
  • Lab tests—focusing on the function of the bone marrow, kidneys, and liver
  • Biopsy
Imaging tests may be recommended to see inside your body structures. These may include:

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include the following:

Chemotherapy

In chemotherapy, drugs are used to kill cancer cells. Chemotherapy drugs travel through the bloodstream to kill cancer cells. Unfortunately, healthy cells and tissues are also damaged in the process. Chemotherapy is often combined with radiation therapy.

Radiation Therapy

Radiation therapy is often delivered at the same time as chemotherapy. Most anal cancers are treated with the combination of radiation therapy and chemotherapy. This treatment can avoid the need for surgery.
In some cases, radiation therapy alone may be used if chemotherapy is thought to result in too many side effects. In the treatment of anal cancer, radiation is delivered externally on a daily basis over 5-6 weeks.
Since radiation therapy damages healthy tissue as well as cancer cells, there are certain side effects associated with radiation therapy for the treatment of anal cancer. Scar tissue may form in the anus, keeping the anal sphincter from working properly. In addition, damage may occur that results in chronic rectal bleeding.

Surgery

Local Resection
Local resection allows for the removal of small cancers that have not spread to nearby lymph nodes or tissues. During this procedure, a small margin of healthy tissue around the cancers will also be removed. This surgery preserves anal function and the need for a permanent colostomy.
Abdominoperineal Resection (APR)
An abdominoperineal resection (APR) is a surgery where the anus and rectum are removed by open surgery. This surgery is considered if the cancer cannot be treated or returns after chemotherapy and radiation. This surgery results in the formation of a permanent colostomy. A colostomy is a surgical opening through the wall of the abdomen into the colon. This is used as a path for waste material to leave the body. After a colostomy, you will wear a special bag to collect body waste.
An abdominoperineal resection (APR) is a surgery where the anus and rectum are removed by open surgery. This surgery is considered if the cancer cannot be treated or returns after chemotherapy and radiation. This surgery results in the formation of a permanent colostomy. A colostomy is a surgical opening through the wall of the abdomen into the colon. This is used as a path for waste material to leave the body. After a colostomy, you will wear a special bag to collect body waste.

Prevention

You may be able to reduce your risk of anal cancer by reducing your exposure to HIV and HPV. There is a vaccine available, called Gardasil, that protects against four types of HPV.

RESOURCES

American Cancer Society http://www.cancer.org

National Cancer Institute http://www.cancer.gov

CANADIAN RESOURCES

Canadian Cancer Society http://www.cancer.ca

Public Health Agency of Canada http://www.phac-aspc.gc.ca

References

Anal cancer. American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003083-pdf.pdf. Accessed May 23, 2013.

Anal cancer. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated May 14, 2013. Accessed May 23, 2013.

Anal cancer. National Cancer Institute website. Available at: http://www.cancer.gov/cancertopics/types/anal. Accessed May 23, 2013.

Joura EA, Leodolter S, Hernandez-Avila M, et al. Efficacy of a quadrivalent prophylactic human papillomavirus (types 6, 11, 16, and 18) L1 virus-like-particle vaccine against high-grade vulval and vaginal lesions: a combined analysis of three randomised clinical trials. Lancet. 2007; 369:1693.

Uronis HE, Bendell JC. Anal cancer: an overview. Oncologist. 2007;12:524-534.

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