title: Association between free testosterone levels and anal human papillomavirus types 16/18 infections in a cohort of men who have sex with men.
abstract: BACKGROUND
  Human papillomavirus (HPV) types 16 and 18 cause invasive cervical cancer and most invasive anal cancers (IACs). Overall, IAC rates are highest among men who have sex with men (MSM), especially MSM with HIV infection. Testosterone is prescribed for men showing hypogonadism and HIV-related wasting. While there are direct and indirect physiological effects of testosterone in males, its role in anal HPV16/18 infections in men is unknown.
  
  
  METHODS
  Free testosterone (FT) was measured in serum from 340 Multicenter AIDS Cohort Study (MACS) participants who were tested for anal HPV16/18-DNA approximately 36 months later. The effect of log10-transformed current FT level on anal HPV16/18 prevalence was modeled using Poisson regression with robust error variance. Multivariate models controlled for other HPV types, cumulative years of exogenous testosterone use, race, age, lifetime number of receptive anal intercourse partnerships, body mass index, tobacco smoking, HIV-infection and CD4+ T-cell counts among HIV-infected, and blood draw timing.
  
  
  RESULTS
  Participants were, on average, 60 (+5.4) years of age, White (86%), and HIV-uninfected (56%); Twenty-four percent tested positive for anal HPV16 and/or 18-DNA (HPV16 prevalence=17.1%, HPV18=9.1%). In adjusted analysis, each half-log10 increase of FT was associated with a 1.9-fold (95% Confidence Interval: 1.11, 3.24) higher HPV16/18 prevalence. Additionally, other Group 1 high-risk HPVs were associated with a 1.56-fold (1.03, 2.37) higher HPV16/18 prevalence. Traditional risk factors for HPV16/18 infection (age, tobacco smoking; lifetime number of sexual partners, including the number of receptive anal intercourse partnerships within 24 months preceding HPV testing) were poorly correlated with one another and not statistically significantly associated with higher prevalence of HPV16/18 infection in unadjusted and adjusted analyses.
  
  
  CONCLUSIONS
  Higher free testosterone was associated with increased HPV16/18 prevalence measured approximately three years later, independent of sexual behavior and other potential confounders. The mechanisms underlying this association remain unclear and warrant further study.
authors: School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America.
authors: Hilary K
authors: HK
authors: Hsu
authors: School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors: Todd T
authors: TT
authors: Brown
authors: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors: Xiuhong
authors: X
authors: Li
authors: Tricore Reference Laboratories, University of New Mexico, Albuquerque, New Mexico, United States of America.
authors: Stephen
authors: S
authors: Young
authors: Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors: Ross D
authors: RD
authors: Cranston
authors: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors: Gypsyamber
authors: G
authors: D'Souza
authors: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors: Lisa P
authors: LP
authors: Jacobson
authors: David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America; Jonathan and Karin Fielding School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America.
authors: Otoniel
authors: O
authors: Martínez-Maza
authors: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors: Eric C
authors: EC
authors: Seaberg
authors: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors: Joseph B
authors: JB
authors: Margolick
authors: Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors: Frank J
authors: FJ
authors: Jenkins
authors: School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America; Desert AIDS Project, Palm Springs, California, United States of America.
authors: Matthew G
authors: MG
authors: Moran
authors: School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America.
authors: Kristofer
authors: K
authors: Chua
authors: Los Angeles LGBT Center, Jeffrey Goodman Clinic, Hollywood, California, United States of America.
authors: Robert K
authors: RK
authors: Bolan
authors: Jonathan and Karin Fielding School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America.
authors: Roger
authors: R
authors: Detels
authors: School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America.
authors: Dorothy J
authors: DJ
authors: Wiley
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001003:Anal Canal / Q000821:virology*; D015331:Cohort Studies; D060085:Coinfection; D015658:HIV Infections / Q000453:epidemiology; D018451:Homosexuality, Male; D052162:Human papillomavirus 16; D052161:Human papillomavirus 18; D006801:Humans; D008297:Male; D008875:Middle Aged; D030361:Papillomavirus Infections / Q000097:blood* / Q000453:epidemiology / Q000821:virology*; D012307:Risk Factors; D012725:Sexual Behavior; D012747:Sexual Partners; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone