Effect of Sequence of Radiotherapy Combined With Immunotherapy on the Incidence of Pneumonitis in Patients With Lung Cancer: A Systematic Review and Network Meta-Analysis

With the widespread application of immune checkpoint inhibitor (ICI) combined with radiotherapy (RT) for the treatment of lung cancer, increasing attention has been paid to treatment-related pneumonitis. The effect of the treatment sequence on the incidence of pneumonitis remains unclear.We searched databases including PubMed, Embase, and ClinicalTrials.gov, meeting abstracts, and reference lists of relevant review articles for literature published on radio- and immunotherapy in lung cancer. Stata software (version 16.0) was used for meta-analysis. Data on the incidence of any grade and ≥ grade 3 pneumonitis was pooled using the random effects model. Bayesian network meta-analysis was used for arm-based pairwise comparisons. Subgroup analyses were performed to identify the potential influencing factors.Thirty-eight studies met our inclusion criteria. The network meta-analysis showed no significant difference between the incidence of pneumonitis in concurrent ICI with RT (concurrent arm) and RT followed by ICI (RT-first arm) (odds ratio [OR]: 0.71, 95% confidence interval [CI]: 0.10-4.81). In the meta-analysis of single group rates, RT following ICI (ICI-first arm) exhibited higher incidence of any grade pneumonitis compared with concurrent- and RT-first arms, with 0.321 (95% CI: 0.260-0.386) for programmed cell death protein 1 (PD-1) inhibitors from clinical trials, and 0.480 (95% CI: 0.363-0.598) for PD-1 inhibitors from real-world retrospective data, respectively.No significant difference in the incidence of any grade and grade ≥ 3 pneumonitis was found between RT-first and concurrent arms. The ICI-first arm exhibited a higher incidence of pneumonitis, which needs to be further confirmed by follow-up studies.