Anal Cytology Abnormalities in HIV-Infected Men: Are Heterosexual Males at Risk?

Background: HIV-infected persons, and especially men who have sex with men (MSM) are at markedly increased risk for anal cancer.  Anal HPV infection and immunosuppression are thought to be the causes.  Screening with anal cytology has been proposed to detect pre-cancerous lesions in HIV-infected MSM, but it is unclear if HIV-infected heterosexual men (HM) benefit from testing.  The purpose of this study is to compare results of anal cytology testing in HIV-infected HM and MSM.

Methods: We identified all anal cytology tests performed at Mount Sinai Medical Center in HIV-infected men from 2005-2012.  We collected data on demographics, anti-retroviral use, and subsequent high-resolution anoscopy (HRA) findings. We compared rates of abnormal anal cytology, histology, and frequency of biopsy by sexual risk group.

Results: In our cohort of HIV-infected men, 456 identified as MSM and 123 as HM.   HM were older than MSM (median age 53 vs. 45; p<0.001) and more likely to have smoked (p=0.03).  There was no significant difference in anti-retroviral use between groups.  66% of MSM and 32% of HM had abnormal cytology of atypical cells of undetermined significance (ASCUS) or worse (p <0.001). HM were less likely than MSM to ever have LSIL (13% vs. 26%; p=0.001) on cytology. MSM had a higher mean number of cytology tests (1.9 vs 1.6; p=0.002). In patients with initial benign cytology and then subsequent cytologic screens, MSM were more likely to develop an abnormality (40% vs 9%; p=0.001).  HRA with biopsy was performed on 250 of the patients. HM and MSM with abnormal anal cytology were equally likely to be evaluated with HRA and biopsy (p=0.3) and no HM had high-grade dysplasia histology. 

Conclusion: Heterosexual men appear to have a lower risk for abnormal anal cytology and HSIL histology than MSM.  Further research is needed to determine the clinical and economic effectiveness of anal cytology screening to prevent anal cancer in HIV-infected HM.