PROJECTIONS OF RACIAL AND ETHNIC DISPARITIES IN HUMAN PAPILLOMAVIRUS (HPV)-RELATED CANCER BURDEN FOLLOWING INTRODUCTION OF HPV VACCINATION IN THE UNITED STATES

Purpose: The introduction of human papillomavirus (HPV) vaccines, which protect against cancer-causing HPV types, in the United States (U.S.) provides opportunities for primary prevention of several cancers and may also alleviate existing racial/ethnic disparities. Our objective was to project changes in HPV-associated cancer incidence and mortality among racial/ethnic groups under various coverage assumptions with the currently available bivalent and quadrivalent HPV vaccines, as well as with the newly-approved nonavalent vaccine, which protects against 7 oncogenic HPV types.

Methods: We employed cancer-specific mathematical models to project the lifetime risks of developing and dying from six HPV-associated cancers under alternative HPV vaccination scenarios. The models reflected gender-, age- and racial/ethnic-specific heterogeneities in HPV type distribution, cancer incidence, and survival in order to project potential widening or narrowing of disparities across five racial/ethnic subgroups. We assumed current U.S. HPV vaccination coverage rates, as well as scenarios of high (e.g., measles, mumps, rubella) coverage. We assumed 100% lifelong efficacy against the HPV genotypes targeted by the vaccine. Summary metrics for overall changes in disparity included the absolute, relative, and index of disparity, using the “best-off” racial/ethnic group as the reference group.

Results: For those individuals not vaccinated against HPV, the burden of HPV-related cancers was the highest among black non-Hispanics and lowest among American Indian/Alaska Natives (AI/AN). Although the absolute risks of developing and dying from HPV-associated cancers decreased under all HPV vaccination scenarios, several disparity‑gaps were projected to widen. For example, compared with no vaccination, the relative disparity gap decreased by 11% for HPV‑associated cancer incidence, but increased by 13% for HPV-associated cancer mortality. Furthermore, several metrics of mortality disparity were the widest when we assumed high vaccination coverage using the nonavalent vaccine.

Conclusions: Implementation of the HPV vaccine has the potential to reduce disparities induced by differential access to health care; however, even with the broad-coverage nonavalent vaccine, disparities will likely still exist and may widen if unequal access to preventive services and cancer treatments persist.