Objective:

To assess the effect of adjuvant HPV vaccination on CIN2+ recurrence following conization through a systematic review and meta-analysis.

Approach:

• Systematic Review and Meta-Analysis: Included 17 studies with 33,181 women, yielding a pooled relative risk (RR) of 0.38 (95% CI 0.29-0.51) indicating a 62% lower recurrence risk.
• Re-analysis of Randomised Trials: Combined data from four RCTs, resulting in a pooled RR of 0.56 (95% CI, 0.36–0.86), indicating a 44% reduction in recurrence.

Key Findings:

• Observational studies showed a higher RR (0.29) compared to randomised trials (0.55).
• The trim-and-fill adjusted estimate of 0.50 suggests potential overestimation in observational data.
• All four RCTs indicated a consistent direction of effect despite methodological limitations.

Interpretation:

The analysis suggests that the treatment effect of HPV vaccination on CIN2+ recurrence is more modest than previously indicated by observational studies.

Limitations:

• Observational studies are susceptible to healthy user bias.
• Three of the four RCTs had an open-label design and were underpowered.
• The pooled estimate is less precise due to methodological heterogeneity.

Conclusion:

Future evidence syntheses should report estimates by study design to better reflect the magnitude of effect.

Sources:

• Frontiers in Oncology