Efficacy of L1 Protein Vaccines Against Cervical and Vaginal Cancer: A Systematic Review and Meta-Analysis

Context: Cervical and genital infections are responsible for the more common sexually transmitted cancers among women aged 14 - 55 years. There are more than 100 HPV types which cause 60% - 70% (high risk types: 16, 18) and 90% (low risk types: 6, 11) cervical cancers. This study aimed to evaluate the efficacy of L1 protein vaccines against cervical and vaginal cancer.
Evidence Acquisition: Different databases (including Scopus, Google scholar, PubMed, Cochrane, and Science Direct) were searched using relevant keywords such as Gardasil, Cervarix, and cervical cancer. After restricting the search strategy and excluding duplicates, the remained articles were screened by investigating their titles, abstracts, and full texts. Cochrane Q-test and I-squared index were used to detect the heterogeneity among the results, and fixed effect model was applied to estimate the pooled risk ratio.
By combining the results of 10 primary articles, the efficacy of monovalent (HPV16), bivalent (HPV 16, 18), and quadrivalent (HPV16,11,6,8) vaccines was estimated between 86% and 100%.
The results of this meta-analysis showed that Gardasil and Cervarix vaccines are highly effective against cervical cancer. According to the point that approximately 50% of cervical cancers and human carcinogenicity are related to HPV-16 infection, the bivalent HPV vaccine might have protective effects against HPV-16 CIN2-3 lesion and cervical cancer.