Background: The aim of this work was to evaluate the role of human papillomavirus (HPV) testing and anal cytology, considering a population of HIV-positive and negative men who have sex with men (MSM), at high risk of sexually transmitted diseases (STD), in order to ascertain which of the methods examined is the best screening strategy for the prevention of anal cancer.
Methods: In the period 06/2013-07/2014 at the "MTS Centre" of the University of Florence, 87 male patients, homo/bi-sexual, of which 46 HIV-negative and 41 HIV-positive, were recruited for anal Pap smear and HPV testing. All patients with an "abnormal" cytological result underwent anoscopy with possible biopsy.
Results: HPV testing was positive in 73 patients (83.6%). Cytology was negative in 50 patients (57.5%), inconclusive in 14 patients (16.1%), abnormal in 23 patients (26.4%): 14 ASC-US (19.2%), 4 ASC-H (5.5%), 5 L-SIL (6.8%), 0 H-SIL. Anoscopy with biopsy led to diagnosis of AIN I in 10 cases, of which 6 ASC-US+ and 4L-SIL+, AIN II in only 1 case, LS-IL+.
Conclusions: Anal HPV testing, when used in primary screening, lead to a high number of "false positives", given the too high prevalence of HPV infection in MSM, the highest risk population targeted for screening. So we propose a screening program with anal cytology which has a high sensitivity for detection of AIN while is a poor predictor of the severity of these lesions; therefore, all patients with abnormal anal Pap smear should undergo anoscopy with biopsy.