Safety analysis of immunochemotherapy combined with consolidative thoracic radiotherapy for extensive-stage small cell lung cancer

Background: Thoracic radiation therapy (TRT) has been shown to improve local tumour control and provide survival benefits for patients with extensive-stage small cell lung cancer (ES-SCLC) in the era of chemotherapy. However, there are no data to indicate the safety, especially the lung toxicity, of TRT during and following the administration of four cycles of programmed death ligand 1 (PD-L1) inhibitors when used with etoposide and platinum (EP). Hence, this retrospective study aimed to investigate the risk factors for radiation pneumonitis (RP) associated with TRT combined with PD-L1 inhibitors. Methods: : From January 2020, through March 2021, in Shandong Cancer Hospital and Institute, patients with ES-SCLC who received TRT during maintenance with PD-L1 inhibitors combined with EP were enrolled in this retrospective study. RP was investigated and evaluated according to the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v5.0) criteria. We used univariate and multivariate logistic regression to analyse the potential risk factors for RP. Results: : From January 2020, to March 2021, 20 patients receiving TRT during maintenance with PD-L1 inhibitors combined with EP were enrolled in this retrospective study. The dose fractions were 1.5 Gy bid or 1.8-3 Gy qd, and the total dose was 30 Gy to 61.4 As a result, 6 patients (30%) experienced grade 2 RP, and no cases of ≥3 grade RP occurred. At the last follow-up, 17 patients suffered from disease progression, 13 suffered from distant progression, three suffered from local failure in the radiation field, and one suffered from distant progression and local failure in the radiation field. The median progression-free time (PFS) was 9 months. Conclusion: The retrospective analysis showed that the lung toxicity resulting from TRT was tolerable during maintenance with PD-L1 inhibitors combined with EP.