Anal cancer overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mohamad Alkateb, MBBCh [2]
Overview
Anal cancer is a type of cancer which arises from the anus, the distal orifice of the gastrointestinal tract. It is a distinct entity from the more common colorectal cancer. The etiology, risk factors, clinical progression, staging, and treatment are all different. Anal cancer is typically a squamous cell carcinoma that arises near the squamocolumnar junction and its often linked to human papillomavirus (HPV) infection. It may be keratinizing (basaloid) or non-keratinizing (cloacogenic). Other types of anal cancer are adenocarcinoma, lymphoma, sarcoma or melanoma. Treatment depends on the stage of the disease at the time of diagnosis.
Classification
Anal cancer may be classified according to histology into four subtypes: squamous cell carcinoma, adenocarcinoma, lymphoma, and sarcoma.
Pathophysiology
Anal cancer most commonly arises from squamous cells at the squamocolumnar junction. Other types of anal cancer are adenocarcinoma, lymphoma, and sarcoma.
Epidemiology and Demographics
In 2008-2012, the incidence of anal cancer was estimated to be 1.8 cases per 100,000 individuals in the US.
Risk Factor
The most potent risk factor in the development of anal cancer is Human Papillomavirus (HPV). Other risk factors include receptive anal intercourse with multiple sexual partners, smoking, and immunosuppression.
Screening
Screening for anal cancer by pap smear is suggested among HIV-positive patients and homosexual men.