(264) Human papillomavirus vaccination among Adolescents and Young Adults who have been treated for cancer: a matched comparative cohort study from the French National Health Data System

Background: In France, vaccination against HPV is recommended between ages 11 and 14, or 15 to 19 for catch-up vaccination (CUV). Lower rates of Human Papillomavirus (HPV) vaccination have been reported among Adolescents and Young Adults (AYAs, aged 15-25) who have undergone cancer treatment, compared to the general population. However, conflicting findings persist, and data on this subject in France are lacking.

Objectives: To assess compliance with HPV vaccination recommendations among AYAs who have undergone cancer treatment compared to AYAs without cancer.

Methods: A retrospective cohort study with exposed-unexposed design was conducted using the French National Health Data System (SNDS). The exposed group included AYAs who underwent cancer treatment between 2012 and 2014, while the unexposed group involved AYAs without cancer or chronic disease. Both cohorts were matched in a 1:1 ratio at the index date, which was two years after the entry date (i.e., start of cancer treatment for exposed AYAs). HPV vaccination rates were compared between exposed and unexposed AYAs over a 5-year period. All HPV vaccine types (bivalent, quadrivalent, and nonavalent) were considered. Given the age range of the cohort, emphasis was placed on CUV among AYAs aged 17 to 19 at the index date. To identify AYAs requiring CUV, data on the completion of initial vaccination were collected. Initial vaccination was deemed achieved if two injections were administered; otherwise, CUV was expected. A Sankey diagram was used to visualize paths and proportion of vaccinations. Association between vaccination coverage and exposure status was assessed by logistic regression models with generalized estimating equations. Results were expressed as Odds Ratio (OR), with 95% confidence intervals (95% CI) and p-value (p).

Results: A total of 3,663 AYAs undergoing active treatment were selected and matched to AYAs without cancer. Within each group, 453 AYAs were aged 17 to 19 and therefore eligible for CUV during cancer management or follow-up. Among the exposed group 15.9% of AYAs had completed their initial vaccination before the entry date, compared to 11.7% in unexposed group (OR 1.43, 95% CI 0.97-2.10; p=0.07). Subsequently, for those requiring the CUV, exposed AYAs were more likely to undergo it, with an initiation rate of 28.0%, compared to 18.5% in the unexposed group (1.72, 1.23-2.41; p< 0.01). Among them, 20.6% underwent CUV during follow-up period, while only 5.4% of unexposed AYAs did.

Conclusions: This study highlights that AYAs who have undergone cancer treatment were more likely to follow HPV vaccination, compared to AYAs without cancer. However, the vaccination rates remain modest, underscoring the need to improve vaccine coverage for all young women.