Efficacy and Safety of Radiotherapy Plus Immunochemotherapy in Patients with Oligometastatic Esophageal Cancer

Abstract

Abstract Background and purpose: Immunotherapy had revolutionized the treatment of metastatic esophageal cancer. Oligometastasis is a limited-metastatic state, and patients at this stage may benefit from metastatic-directed local treatments, which may increase their chances of survival. As an immunomodulator, radiotherapy (RT) might achieve a synergistic effect when combined with immunotherapy. Compared to immunochemotherapy alone, this study assessed the efficacy and safety of radiotherapy plus immunochemotherapy in de-novo oligometastatic esophageal cancer (EC). Materials and methods: In this trial, we retrospectively collected esophageal cancer patients with de-novo oligometastases and received immunochemotherapy. The primary endpoints were progression-free survival (PFS) and overall survival (OS).Secondary endpoints were objective response rate (ORR), disease control rate (DCR), duration of response (DOR), and treatment-related adverse events (TREAs). Results: Between Jan 2019 and Jan 2022, 226 patients were included, which consisted of 108 cases in the RT plus immunochemotherapy (iCRT) group, and 118 cases in the immunochemotherapy (iCT) group. With a median follow-up of 22.2 months, the median PFS (mPFS) was 13.0 months for the iCRT group and 7.7 months for the iCT group (P＜0.001, HR=0.520, 95% CI, 0.388-0.696). In terms of OS, the median OS (mOS) was 27.5 months for the iCRT group and 21.7 months for the iCT group (P=0.026, HR=0.670, 95% CI, 0.468-0.958). The iCRT group compared with the iCT group was associated with a higher risk of ≥ grade 3 myelosuppression. No other grade 5 TRAEs or new safety signals were observed. Through univariate and multivariate analysis, we also found that, besides local radiotherapy, oligometastatic esophageal cancer (OMEC) patients with a history of alcohol consumption, more metastatic lesions, and second-line and above treatment had inferior PFS. And a lower KPS score, a greater number of metastatic lesions, and second-line and above treatment were found to have inferior OS. Conclusion: Compared to immunochemotherapy alone, radiotherapy plus immunochemotherapy showed survival benefits with manageable safety for oligometastatic esophageal cancer patients. It deserves to be validated in a larger trial.