Cancers caused by the human papillomavirus (HPV) affect both men and women in large numbers, but prevention efforts initially focused on women (see related CIDRAP News story today). A retrospective cohort study published last week in JAMA Oncology suggests that vaccinating boys and young men with the nine-valent (nine-strain) HPV vaccine can meaningfully reduce their risk of related cancers, supporting the case for sex-neutral vaccination programs.
HPV vaccination has long been framed as a way to prevent cervical cancer in women, but the virus causes a range of cancers that affect men, including head and neck, anal, and penile cancers. In the study, researchers from the Nara Prefecture General Medical Center in Nara, Japan, looked at large-scale population data to evaluate the effectiveness of the nine-valent HPV vaccine in preventing these cancers in men.
Greatest benefit when given to older teens, young adults
By examining health data from 510,260 vaccinated males and the same number of unvaccinated males ages nine to 26 years over as many as 10 years of follow-up, the researchers found that receipt of at least one dose of the vaccine was associated with a significantly lower risk of related cancers.
Overall, vaccinated boys and men had about half the risk of HPV-related cancers than that of unvaccinated peers (hazard ratio [HR], 0.54). Protection was consistent across both age-groups the researchers looked at—males vaccinated from ages 9 to 14 years had a 42% lower risk (HR, 0.58), and those vaccinated from ages 15 to 26 had a 50% lower risk (HR, 0.50).
The authors note that most previous research on the link between HPV vaccination in men and HPV-related cancers has focused on adults, who may have been previously exposed to HPV, potentially reducing the observed effect. The current findings suggest that vaccination confers benefits for men when administered later in adolescence or young adulthood.
Vaccine should be available ‘irrespective of sex’
The findings have important implications for vaccination policies. HPV vaccination programs have focused primarily on women because of the link between HPV and cervical cancers.
“Currently, many countries still implement HPV vaccination only for females,” write the researchers, noting that males account for approximately 10% to 15% of the vaccinated cohort outside the United States. (In 2024, approximately 77% of boys ages 13 to 17 in the United States had received one or more doses of the HPV vaccine.) “Our study provides evidence that HPV vaccination should be accessible irrespective of sex.”
The study has several limitations, including misclassified or unconfirmed diagnoses due to reliance on standardized medical diagnosis codes, vaccination outside of participating health care systems, and an inability to adjust for high-risk sexual behaviors.
Still, the findings add to a growing body of evidence that the benefits of HPV vaccination extend beyond preventing cervical cancer in women. “Our study indicates that 9v-HPV vaccines should be administered not only to females but also to young males,” conclude the researchers.
