20. Utility of human papillomavirus (HPV) 16 E6 and L1 DNA levels for anal cancer screening in HIV-infected individuals

Background In this prospective study we evaluate the sampling performance of HPV16 DNA E6 and L1 levels in detecting anal intraepithelial neoplasm using either a moistened Dacron swab (DS) or cytobrush (CB). Methods: We recruited HIV-infected (n = 57) and organ-transplanted subjects (n = 3) with an abnormal anal Pap smear who presented for high-resolution anoscopy (HRA). Prior to HRA, the first 30 subjects underwent sampling with a moistened DS, and the next 30 with a CB. HRA was then performed in the usual fashion. Samples were tested for HPV16 DNA E6 and L1 DNA using a validated qPCR technique. Anal biopsies were taken as per standard-of-care and categorised as negative, AIN 1/warts, or AIN 2 or 3. Results: 59 of 60 samples had adequate DNA and were evaluated for the comparison of HPV16 E6 and L1 DNA levels. A CB performed better than the DS in detecting low positive and positive levels of HPV16 E6 DNA (P = 0.01). We then further evaluated the correlation of HRA-directed biopsies and HPV16 DNA E6 levels. There was a positive correlation of HRA-directed biopsy results stratified by increasing histological levels with HPV16 E6 DNA (P = 0.018, Kruskal–Wallis test). Conclusions: A CB performed better than DS for molecular HPV testing. If molecular testing is included in anal cancer screening, consideration should be made for co-sampling with both a DS for cytology and CB for HPV testing. Further studies evaluating the sample yields should be performed to assist in implementation of anal cancer screening programs in defined populations of at-risk individuals.