AT THE ASPO ANNUAL MEETING
BIRMINGHAM, ALA. – Serum antibodies induced by a natural human papillomavirus type 16 infection do not appear to protect against acquisition of a subsequent oral HPV 16 infection in men, according to results of the HPV Infection in Men (HIM) study.
That finding is concerning, because about 70% of oropharyngeal cancers in the United States are caused by oral HPV infection. Most are caused by HPV type 16, Christine M. Pierce Campbell, Ph.D. of Moffitt Cancer Center & Research Institute, Tampa and her colleagues reported in a poster at the annual meeting of the American Society of Preventive Oncology.
“HPV antibody status may reflect a man’s history of sexual behavior and partnerships, which may not be sufficiently measured in the risk factor questionnaire. In our study, the proportions of men who have sex with men and men who have sex with women and men who had high levels of antibodies at baseline were substantially greater than the proportion of heterosexual men with high antibody levels,” the researchers wrote. They noted that men with an antibody response may have been exposed to more HPV during their lifetimes, and thus were at greater risk of acquiring new oral HPV.
While naturally induced antibodies may not protect against oral HPV 16 infection, prophylactic HPV vaccination may provide such protection, the investigators said.
Of 1,618 men from the oral HPV 16 subcohort of the prospective natural history study of HPV who were followed for a median of 12.7 months after collection of an initial oral specimen, 17 developed a new incident oral HPV16 infection. Of these 17 men, 11 had low anti-HPV16 serum antibody levels, and 6 had high levels,
Anti-HPV 16 serum antibody levels were not associated with cumulative risk of oral HPV16 infection. During the first year of follow-up, 0.4% of those with low levels vs. 0.8% of those with high levels acquired a new infection. Within 24 months of follow-up, 3.0% of those with low levels vs. 3.5% of those with high levels acquired a new infection.
Those with higher levels were 60% more likely than those with low levels to acquire a new infection (hazard ratio, 1.6), but this finding was not statistically significant, the investigators reported.
Study subjects were men from the United States, Brazil, or Mexico who were aged 18 to 73 years and HIV negative at baseline.
Oral rinse-and-gargle specimens were collected from the men at 6-month intervals for up to 4 years. Low antibody levels were defined as the lowest 3 quartiles of antibody levels in the cohort combined, including those with no detectable antibody, and high levels were defined as the highest quartile.
Because of the rarity of oral HPV, additional study is needed to replicate the findings, they said.
Dr. Campbell was supported in part by a postdoctoral fellowship from the American Cancer Society. The HIM study was supported by a grant from the National Cancer Institute (NCI), by grants and/or other funding to individual authors from Merck, Sharp & Dohme, and from the NCI Intramural Program.