Conventional vs. Volumetric Brachytherapy in the Treatment of Cervix Cancer: A Meta-Analysis of 30 Clinical Studies.

Abstract

To ascertain if there is a difference in local control (LC) and disease-free survival (DFS) between conventional, point A-based brachytherapy (2D) and volume-based brachytherapy (3D) for cervix cancer and to determine which technique demonstrates superior patient outcomes in the form of a meta-analysis. We conducted a meta-analysis seeking 3-year clinical cohort data from prospective and retrospective studies to assess the effects of 2D and 3D brachytherapy. The search criteria included MeSH terms of “cervical neoplasms”, “brachytherapy”, “retrospective studies”, “disease free survival” along with the following terms: “high-dose-rate brachytherapy”, “survival analysis” and “local control”. This electronic search, as well as a search through reference sections of suitable studies yielded a total of 5145 studies. From these, 317 relevant full-text articles were screened and assessed for eligibility. Risk of bias was assessed by 2 separate reviewers through the CASP cohort study checklist and a personalized checklist assessing appropriateness of cervical carcinoma treatment. A final number of 30 studies were found to be relevant and met the quality criteria to be included for analysis. Patients included were from stages IB2-IVB, treated from 1995. in the 30 clinical studies. Treatment included concomitant chemo-radiotherapy and high-dose rate (HDR) brachytherapy (either 2D or 3D). Minimum follow-up was 2 years and outcomes were reported at 3 years. Weighted averages of aggregated (all stages combined) local control (LC) and disease-free survival (DFS) were calculated. Confidence intervals for the average weighted means and forest plots for the same were calculated. From a total of 30 studies, 5406 patients that presented 3-year aggregated LC and DFS, we found significant differences between 2D and 3D brachytherapy. Regarding 3-year aggregated LC, 27 studies (5821 patients) reported this outcome. The baseline LC for this entire cohort was 88.6%. According to brachytherapy type, 2D brachytherapy showed a LC of 86% (95% CI 83% – 89%) and 3D brachytherapy 92% (95% CI 90% - 93%). This 6% difference was statistically significant (p = 0.0005). With reference to DFS, 22 studies (4563 patients) reported this outcome. The baseline 3y DFS for the cohort was 73.4%. According to brachytherapy type, 2D brachytherapy showed a DFS of 69% (95% CI 64 – 74%) and 3D brachytherapy was associated with 3 yr DFS of 75% (95% CI 72 - 78) for patients treated with 3D brachytherapy. This 6% improvements in LC and DFS were statistically significant (p = 0.0005, p = 0.03). Volumetric-based (3D) brachytherapy as treatment for cervical carcinoma patients results in superior 3-year LC and DFS relative to point A based (2D) brachytherapy. These results can be translated into population impact and can inform policymakers to upgrade national radiotherapy practices. It can also be used as a starting point for clinical trials to explore long-term clinical outcomes.