Causal attribution of human papillomavirus genotypes to invasive cervical cancer worldwide: a systematic analysis of the global literature.

ABSTRACT

BACKGROUND: Understanding the proportion of invasive cervical cancer (ICC) caused by different human papillomavirus (HPV) genotypes can inform primary (ie, vaccination) and secondary (ie, screening) prevention efforts that target specific HPV genotypes. However, using the global literature to estimate population attributable fractions (AFs) requires a methodological framework to address HPV genotype-specific causality from aggregated data. We aimed to estimate the proportion of ICC caused by different HPV genotypes at the global, regional, and national level. METHODS: This systematic review identified studies reporting HPV genotype-specific prevalence in ICC or people with normal cervical cytology. We searched PubMed, Embase, Scopus, and Web of Science up to Feb 29, 2024, using the search terms "cervix" and "HPV", with no language restrictions. Odds ratios (ORs) were estimated by comparing HPV genotype-specific prevalence between HPV-positive ICC and normal cervical cytology with logistic regression models, adjusting for region, year of paper publication, and HPV primer or test. HPV genotypes with a lower bound to the 95% CI of the OR greater than 1·0 were judged as causal to ICC. Corresponding regional genotype-specific AFs were calculated as regional HPV prevalence in ICC multiplied by (1 - [1 / OR]) and were proportionally adjusted to total 100%. Global AFs were calculated from regional AFs weighted by number of regional ICC cases in 2022 (GLOBOCAN). FINDINGS: The systematic review identified 1174 studies with 111 902 cases of HPV-positive ICC and 2 755 734 of normal cervical cytology. 17 HPV genotypes were considered causal to ICC, with ORs ranging widely from 48·3 (95% CI 45·7-50·9) for HPV16 to 1·4 (1·2-1·7) for HPV51. HPV16 had the highest global AF (61·7%), followed by HPV18 (15·3%), HPV45 (4·8%), HPV33 (3·8%), HPV58 (3·5%), HPV31 (2·8%), and HPV52 (2·8%). Remaining causal genotypes (HPV35, 59, 39, 56, 51, 68, 73, 26, 69, and 82) had a combined global AF of 5·3%. AFs for HPV16 and 18 and HPV16, 18, 31, 33, 45, 52, and 58 combined were lowest in Africa (71·9% and 92·1%, respectively) and highest in central, western, and southern Asia (83·2% and 95·9%, respectively). HPV35 had a higher AF in Africa (3·6%) than other regions (0·6-1·6%). INTERPRETATION: This study provides a comprehensive global picture of HPV genotype-specific AFs in ICC, before the influence of HPV vaccination. These data can inform HPV genotype-specific vaccination and screening strategies to reduce the burden of ICC. FUNDING: EU Horizon 2020 Research and Innovation Programme.