TY - CHAP M1 - Book, Section TI - Carcinoma of the Anus A1 - Ursem, Carling A1 - McQuaid, Kenneth R. A2 - Papadakis, Maxine A. A2 - McPhee, Stephen J. A2 - Rabow, Michael W. A2 - McQuaid, Kenneth R. PY - 2022 T2 - Current Medical Diagnosis & Treatment 2022 AB - The anal canal is lined from its proximal to distal extent by columnar, transitional, and non-keratinized squamous epithelium, which merges at the anal verge with the keratinized perianal skin. Cancers arising from the mucosa of the anal canal are relatively rare, comprising only 1–2% of all cancers of the anus and large intestine. Squamous cancers make up the majority of anal cancers. Anal cancer is increased among people practicing receptive anal intercourse and those with a history of anorectal warts. In over 80% of cases, HPV may be detected, suggesting that this virus is a major causal factor. In a large controlled trial, HPV vaccination of healthy men (16 to 26 years old) who have sex with men decreased the incidence of anal intraepithelial neoplasia by 50%. Women with anal cancer are at increased risk for cervical cancer (which may be due to a field effect of oncogenic HPV infection) and require gynecologic screening and monitoring. Anal cancer is increased in HIV-infected individuals, possibly due to interaction with HPV. Nine-valent HPV (9vHPV) vaccine is recommended for boys and girls starting at age 11 or 12 and for individuals up to age 26 who have not been previously vaccinated. Thereafter, shared clinical decision-making regarding HPV vaccination is recommended for some adults aged 27 through 45 years who are not adequately vaccinated. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1184389875 ER -