What is anal cancer?

Anal cancer is a relatively rare form of cancer that occurs in the tissues of the anus. The anus is at the end of the large intestine, below the rectum, through which stool leaves the body. According to the American Cancer Society, approximately 5,070 new cases of anal cancer will be diagnosed and there will be 680 deaths in 2008.

Occasionally, skin cancer, such as melanoma, may be found in the anal area.

What are the symptoms of anal cancer?

Signs and symptoms of anal cancer may include:

• Bleeding from the anus or rectum
• A lump, mass or growth in or near the anus
• Pain or pressure in the area of the anus
• Itching or discharge from the anus
• A change in bowel habits

Some individuals may not experience any signs or symptoms.

What are the risk factors for anal cancer?

• sex

  Women are at higher risk of anal cancer than men.

• age

  The risk of anal cancer increases with age; most cases occur in individuals 50 years and older.

• having many sexual partners

• having receptive anal sex

• smoking

  Current cigarette use may increase your risk for anal cancer. Former smokers have a slightly elevated risk.

• Human papillomavirus (HPV)

  A diagnosis of HPV, a sexually transmitted disease, increases your risk for anal cancer. HPV may cause abnormal cells in the anus, a condition called anal squamous intraepithelial lesions, which may develop into cancer.

• Drugs or conditions that suppress your immune system

  Individuals who take immunosuppressive drugs, including individuals who have received organ transplants, may have increased risk for anal cancer. Long term use of corticosteroids and HIV may also increase your risk of anal cancer.

What causes anal cancer?

The exact cause of anal cancer is unknown.

Prevention of anal cancer

There is no sure way to prevent anal cancer. You may reduce your risk by:

• Practicing safe sex

• Getting a vaccination for HPV

• Quitting smoking

Screening and diagnosis for anal cancer

It is important that anal evaluation is done by an experienced specialist, as it may be easily missed. Screening and diagnostic methods for anal cancer include the following:

• physical exam and history

• direct visual inspection

• digital rectal examination (DRE) - a physician or healthcare provider inserts a gloved finger into the rectum to feel for anything unusual or abnormal

• anoscopy – an exam of the anus and the lower rectum using a short, lighted tube called an anoscope.

• proctoscopy – an exam of the rectum using a short, lighted tube called a proctoscope

• endoscopic ultrasound

• biopsy

Staging and Prognosis

• Stage 0 (Carcinoma in Situ) –Abnormal cells (squamous cells) are found in the innermost lining of the anus.  These abnormal cells may become cancer and spread into the nearby normal tissue.

• Stage I – Cancer has formed in the anus and the tumor is 2 centimeters or smaller.

• Stage II – The tumor is larger than 2 centimeters

• Stage IIIA – The tumor may be any size and the cancer has spread to either: lymph nodes near the rectum; or nearby organs, such as the vagina, urethra and bladder

• Stage IIIB – The tumor may be any size and the cancer has spread to either: to nearby organs and to lymph nodes near the rectum to lymph nodes on one side of the pelvis and/or groin, and may have spread to nearby organs; or to lymph nodes near the rectum and in the groin, and/or to lymph nodes on both sides of the pelvis and/or groin, and may have spread to nearby organs

• Stage IV – The tumor may be any size and the cancer may have spread to the lymph nodes or nearby organs and has spread to distant sites, such as other organs.

Treatment

Treatment options for anal cancer depend on the stage and location of the cancer, whether the patient has HIV, and whether the cancer remains after initial treatment or has recurred.

• Radiation therapy

  Radiation therapy is the use of high-energy radiation to kill cancer cells and to shrink tumors. There are two ways to deliver radiation therapy:

• • external radiation (external beam therapy)
    
    External beam radiation is a treatment that precisely sends high levels of radiation directly to the cancer cells. The machine is controlled by the radiation therapist. Since radiation is used to kill cancer cells and to shrink tumors, special shields may be used to protect the tissue surrounding the treatment area. Radiation treatments are painless and usually last a few minutes.

• • internal radiation (brachytherapy, implant radiation)
    
    Internal radiation therapy is given inside the body as close to the cancer as possible. Substances that produce radiation, called radioisotopes, may be swallowed, injected or implanted directly into the tumor. Some of the radioactive implants are called “seeds” or “capsules.” Internal radiation involves giving a higher dose of radiation in a shorter time span than with external radiation. Some internal radiation treatments stay in the body temporarily. Other internal treatments stay in the body permanently, though the radioactive substance loses its radiation within a short period of time. In some cases, both internal and external radiation therapies are used.

• Chemotherapy

Chemotherapy is the use of anticancer drugs to treat cancerous cells. In most cases, chemotherapy works by interfering with the cancer cell’s ability to grow or reproduce. Different groups of drugs work in different ways to fight cancer cells. The oncologist will recommend a treatment plan for each individual.

• Surgery

There are two types of surgery which may be options based on the stage of your anal cancer:

• • Local resection

    This is a surgical procedure in which the tumor is cut from the anus along with some of the healthy tissue around it. This can be an option if the cancer is small and has not spread. In this procedure, the sphincter muscles may be saved so the patient can still control bowel movements.

• • Abdominoperineal resection

    A surgical procedure in which the anus, rectum and part of the sigmoid colon are removed through an incision made in the abdomen. The doctor sews the end of the intestine to an opening, called a stoma, made in the surface of the abdomen so waste can be collected in a disposable bag outside the body, called a colostomy.

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Created 6/5/08. Reviewed by S. Mobarhan, MD.