Protocol for the investigation of anal dysplasia by cytology and high resolution anoscopy

Introduction: Anal squamous cell carcinoma (SCC) represents 2% of all colo-recto-anal malignancies. It is confirmed a higher rate of anal cancer among HIV-infected population in comparison with the HIVuninfected population (60/100,000 person-years, versus 2/100,000 person-years). Among HIV-infected men who have sex with men (MSM), the incidence of anal cancer is as high as 92-144/100,000 population. Like cervical cancer, squamous-cell canal cancer is caused predominantly by high-risk, oncogenic strains of human papillomaviruses (HPV) detected in 92% of HIV-positive MSM. The cervical and anal cancer share the same embryological origin, and occurs at a squamo-columnar transition zone, site of squamous intraepithelial lesions (SIL) as a result of the persistence HPV infection, especially the high-risk genotypes that may progress to invasive cancer. In the last decades, the incidence of squamous-cell anal carcinoma is increasing rapidly forcing the research of anal SIL (ASIL) cytology (PAP) and high-resolution anoscopy (HRA) colposcopic technique, emulating protocols for early detection of cervical cancer as a primary prevention. Objective: This study aimed to determine the prevalence of SCC precursor lesions. Determine sensitivity (S), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) for the detection of anal dysplasia in the risk population. Material and Methods: Design prospective, cross-sectional, observational, analytical study. High-risk patients (HIV-positive MSM, patients with history of anogenital HPV, women with history of cancer or lower genital intraepithelial neoplasia) were included consecutively between April 2012 and February 2014 in Anal Early Detection Cancer Clinic...