Objective: Due to long lag time between infection/cancer diagnoses human papillomavirus (HPV) vaccination programs will deliver vaccine efficacy (VE) estimates against cancer end-points late. Cancer registry follow-up of population-based, randomised trial cohorts of vaccinated and unvaccinated women was undertaken for the estimation of VE against cervical intraepithelial neoplasia grade three and invasive cancer (CIN3+).
Methods: We report interim results with 98 561 person years of Finnish Cancer Registry -based follow-up of individually and/or cluster randomised cohorts of HPV-16/18 vaccinated and unvaccinated adolescent women enrolled in June 2003/2005, and between May 2004 and April 2005, respectively. The cohorts comprised 15 627 18- to 19-year-old unvaccinated women (NCT01393470), and 2 401 and 64 16- to 17-year-old HPV-16/18 vaccinated women participating the PATRICIA (NCT00122681) and HPV-012 (NCT00169494) trials, respectively. The age-aligned passive follow-up started 6 months after the clinical trials' end.
Results: During the follow-up of 4.5 to 10 years post enrolment we identified 75 cases of cervical intraepithelial neoplasia grade 3 (CIN3) and 4 cases of invasive cervical cancer (ICC) in the unvaccinated cohort, and 4 CIN3 cases in the HPV-16/18 vaccinated women. Diagnostic blocks were available for HPV typing from 87% of the cases. CIN3+ lesions were detectable in 54 cases. HPV16 was found in 26 of 50 unvaccinated CIN3+ cases, and in 3 CIN3+ cases in the HPV-16/18 vaccinated women. The latter were all baseline positive for cervical HPV16 DNA. Baseline data was not available for the unvaccinated women. Intention-to-treat VE against any CIN3+ was 66% (95% CI 8, 88).
Conclusions: Ten years post vaccination the AS04-adjuvanted HPV-16/18 vaccine shows continued efficacy against CIN3+ irrespectively of HPV type. Vaccine efficacy was not observed in baseline HPV16 DNA positive subjects.
Trial registration number: NCT01393470.
Keywords: HPV vaccines; cervical cancer; cin3+; long-term follow-up; randomized controlled trial; vaccine efficacy.
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