November 25, 2015
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Anal Cancer (cont.)

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Anal cancer screening and early detection

Looking for a disease in people with no symptoms or signs is called screening. Screening is performed to find cancers at an early stage when treatment can be most beneficial. As anal cancer is rare, routine screening of the general public for this condition is not recommended.

In groups at higher risk for anal cancer and especially precancerous lesions called anal intraepithelial neoplasia (AIN), screening is appropriate. This includes men who have sex with men regardless of HIV status, women with histories of cervical and vulvar cancers, all HIV positive patients, post-transplant patients on immunosuppressive medication, and those with a history of anal warts. Anal warts are not themselves considered precancerous, but imply HPV infection is present. Certain dangerous HPV subtypes may indicate the presence of cancer or lead to cancer development.

The screening technique for AIN is called an anal pap smear and uses the same technique used for women's pap smears. A swab is taken from the anal canal and a smear from the swab is submitted for microscopic evaluation by cytology technique. More recently, lab techniques are used to measure the presence and levels of the dangerous HPV (16 and 18) subtypes or the presence of mutations.

Screening frequency recommendations are still being established. For now, men who have sex with men and are HIV negative should be screened every 2 to 3 years. If they are HIV positive, then they should be screened yearly. If an anal pap smear is positive for AIN, the patient should be referred to a surgeon for a biopsy.

How is anal cancer diagnosed?

If a patient is suspected to have anal cancer, the examining physician will first take a medical history and conduct a physical exam. Next, the anal canal can be examined with an anoscope -- a short, lubricated tube with a light on it. The physician can see and inspect the anus, anal canal, and lower rectum with the tool. Other types of scopes can be used to examine the lower colon, rectum, and anal regions. Their use is called endoscopy. Endo-anal or endo-rectal ultrasound (ultrasound probe insertion into the rectum) may be used to detect abnormal rectal structures.

A diagnosis of cancer is always made by a physician called a pathologist who analyzes tissue in a laboratory. The tissue is obtained by biopsy, which refers to the technique of removing a piece of the abnormal appearing or suspicious tissue. This is done under direct visualization either with or through an endoscope, or if directly visible, using a type of biopsy needle under local anesthesia.

The pathologist analyzes the tissue and creates a report describing the type of cancer and its extent within the biopsy specimen.

Medically Reviewed by a Doctor on 10/13/2015



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