Effectiveness and Safety of Carbon Ion Radiotherapy in Solid Tumors: A Systematic Review and Meta-Analysis.

Purpose: This systematic review and meta-analysis aimed to investigate the effectiveness of carbon ion radiotherapy (CIRT) compared to that of conventional radiotherapy in patients with various types of solid tumors.

Materials and methods: We systematically searched eight electronic databases from inception until August 2022 in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. The comparative effectiveness of the different treatment options was assessed by a random-effects meta-analysis.

Results: This review included 34 comparative studies and three treatment groups. Overall, the meta-analysis indicated comparable local control rates between the CIRT and control groups [pooled risk ratio (RR)=1.02, 95% confidence interval (CI) 0.90-1.15]. The local control rate in the CIRT group was higher than that in the photon therapy group, but slightly lower than that in the proton radiation therpy (PRT) group. Additionally, the CIRT group had significantly higher overall survival (OS) (RR=1.19, 95% CI=1.01-1.42) and progression-free survival (PFS) (RR=1.50, 95% CI=1.01-2.21) rates compared to the control group. In the subgroup analysis, survival rates were similar between the CIRT and PRT groups.

Conclusion: CIRT was associated with improved toxicity, local tumor control, OS, and PFS compared to conventional treatments. Therefore, CIRT was found to be a safe and effective option for achieving local control in patients with solid tumors.