Long-term impacts of HPV vaccination strategies on HPV related Cancer burden among Singaporean female population: A prospective simulation using proportional multistate lifetables

To project the long-term health impact, measured in cancer cases averted and Health-Adjusted Life Years (HALYs) gained, of different Human Papillomavirus (HPV) vaccination strategies on the burden of cervical and oropharyngeal cancers in the female population of Singapore. We developed a Proportional Multistate Life Table (PMSLT) model to simulate a cohort of females from age 12 to 100. The model projects future cancer incidence by applying population impact fractions, derived from changes in HPV prevalence, to baseline cancer rates. We compared two intervention scenarios against a “Business as Usual” baseline: (1) a gradual catch-up program modelling a phased increase in vaccination coverage from a baseline of 15% to 90% over 15 years, targeting cohorts aged 17 years and above who were not covered by Singapore's 2019 school-based program, and (2) a hypothetical “HPV eradication” scenario, also phased in over 15 years. The gradual catch-up program was projected to avert a mean of 164,968 (95% UI: 135,721 to 194,154) cervical cancer cases and 4007 (95% UI: 3036 - 4966) oropharyngeal cancer cases over the cohort's lifetime (100 years). This corresponds to a total gain of 120,919 (95% UI: 89,459 - 150,325) HALYs across both cancers. The hypothetical HPV eradication scenario would avert 186,375 (95% UI: 157,662- 214,880) cervical cancer cases and 4518 (95% UI: 3595 to 5465) oropharyngeal cancer cases, gaining 136,521 (95% UI: 106,349 to 166,457) HALYs. A gradual catch-up HPV vaccination program targeting cohorts aged 17 years and above can substantially reduce the future burden of cervical and oropharyngeal cancers in Singapore. A hypothetical HPV Eradication scenario represents the upper bound of achievable benefit, and the catch-up program achieves approximately 89% of this maximum potential gain. These findings strongly support Singapore's ongoing national HPV vaccination strategy.