Effect of Brazil's national human papillomavirus vaccination programme on the incidence of cervical cancer and cervical intraepithelial neoplasia grade 3 in women aged 20–24 years: a population-based study
Studies from high-income countries have shown significant reductions in cervical cancer and cervical intraepithelial neoplasia grade 3 (CIN3) after implementing the human papillomavirus (HPV) vaccination. However, evidence from low-income and middle-income countries remains limited. Therefore, we aimed to evaluate the impact of the Brazilian HPV vaccination programme on the incidence of cervical cancer and CIN3. In this population-based study, we analysed cervical cancer and CIN3 incidence among women aged 20-24 years between 2019 and 2023, using data from the diagnosis, treatment, and hospitalisations (ie, admittance to hospital) databases from Brazil. Birth cohorts were categorised according to the year of birth. The primary outcome was the diagnosis of cervical cancer (ICD-10 code C53) and CIN3 (code D06). Incidence rate ratios were estimated using Bayesian negative binomial regression, adjusting for calendar year, age, and trimester of diagnosis. We used breast cancer as a negative control outcome. The main analysis was conducted using the data from the Painel Oncologia (diagnosis and treatment database). We analysed 60·6 million women-years of follow-up for women aged 20-24 years. 1318 cervical cancer and 2132 CIN3 cases were recorded. The incidence rate ratios comparing the 2001-03 birth cohort to the 1994-98 birth cohort were 0·42 (95% credible interval 0·27-0·66) for cervical cancer and 0·33 (0·20-0·53) for CIN3. The negative control outcome and exposure showed values close to the null with wider credible intervals. Sensitivity analyses using hospitalisation data showed similar results. Brazil's HPV vaccination programme reduced cervical cancer and CIN3 incidence in women aged 20-24 years. These findings underscore the vaccine's potential to reduce health disparities and contribute to the elimination of cervical cancer in low-income and middle-income populations. Royal Society and Conselho Nacional de Desenvolvimento Científico e Tecnológico.