The only category of men who should be tested are homosexuals, and particularly those with suppressed immune systems.
The observation that cancer of the anal canal is 17 times more frequent in passive homosexuals (when there is HIV infection, the risk is in fact much higher), led American researchers to study in detail premalignant lesions and cancer of the anal canal.
The anal canal has metaplastic epithelium similar to that of the uterine cervix, and it is located between the cylindrical epithelium of the rectum and the squamous epithelium of the anus. This is the region where premalignant lesions and cancers caused by carcinogenic HPVs develop. It was found that a preventive Pap test of the anal canal very frequently helps detect abnormal cells. It is not clear however if finding and treating premalignant lesions contributes towards a decrease of anal cancers and this is why no official recommendation has been made by scientific societies towards establishing this method.
