(Reuters) – At current vaccination rates, inoculation against human papillomavirus (HPV) isn’t expected to have much impact on oropharynx cancer incidence in the United States through 2045 because older, unvaccinated individuals remain at high risk, researchers say.
The study team analyzed data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) program on 69,662 patients aged 34-83 years who were diagnosed with oropharynx cancer between 1992 and 2017. They also looked at HPV vaccination rates among 60,124 participants in the National Immunization Survey–Teen and 16,904 participants in the National Health Interview survey.
Based on these data sets, researchers constructed models that accounted for age, period, and cohort to project expected oropharynx cancer incidence from 2018 to 2045 assuming either no HPV vaccination at all or current HPV vaccination levels.
according to the in JAMA Oncology. In 2045, oropharynx cancer rates without HPV vaccination would be 14.3 per 100,000 population, compared with 13.8 per 100,000 with vaccination.
“HPV vaccination is going to work to prevent oropharyngeal cancers, but it will take time to see that impact, because these cancers mostly occur in middle age,” said senior study author Gypsyamber D’Souza, a professor of epidemiology at the Johns Hopkins University, Baltimore.
“HPV vaccination works wonderfully protecting against new infections – but vaccination doesn’t treat infections we already have – so older individuals outside the ages targeted for HPV vaccination will continue to be at risk of these cancers,” D’Souza said by email.
Projections looked more promising for the youngest age group in the study, individuals from 36 to 45 years old.
With current HPV vaccination rates, researchers projected that, between 2018 and 2045, oropharynx cancer incidence among younger people 36 to 45 years old would decline from 1.4 to 0.8 per 100,000 population.
For those 46-55 years of age, oropharynx cancer incidence would dip less dramatically between 2018 and 2045, from 8.7 to 7.2 per 100,000 population.
Among the oldest people in the study – those 70-83 years old – oropharynx cancer incidence is projected to rise from 16.8 per 100,000 population in 2018 to 29.0 per 100,000 population in 2045.
Overall, HPV vaccination may reduce oropharynx cancer incidence by 48.1% for men and by 42.5% for women aged 36-45 years, by 2045, the researchers also calculated.
Also by that year, HPV vaccination may decrease oropharynx cancer incidence by 9.0% for men and by 22.6% for women aged 46-55 years.
Oropharynx cancer rates won’t significantly fall by 2045 for individuals over 56 years of age, however.
Researchers projected that, between 2018 and 2045, HPV vaccination will prevent a total of 6,334 cases of oropharynx cancers. The vast majority of these cases (88.8%) would be in people 55 years and younger.
“HPV vaccination will prevent cancer and it is important to continue to improve our current HPV vaccination rates, but it will take decades to fully realize this benefit,” D’Souza said. “By 2045, HPV vaccination done over the past decade will have begun to make a significant impact.”
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