Abstract
BACKGROUND: Chemotherapy plus immunotherapy has become the standard first-line treatment of advanced or metastatic esophageal squamous cell carcinoma (ESCC), but median duration of response is only 7.0-8.3 months and progression-free survival (PFS, ∼6 months) is still far from satisfactory. We aim to evaluate whether early involvement of radiotherapy might improve the treatment outcome if objective response to first-line chemo-immunotherapy was observed in locally advanced or metastatic ESCC. METHODS: Patients were retrospectively collected from 3 institutions in China. Patients with histopathologically confirmed diagnoses of locally advanced or metastatic ESCC were identified, who objectively responded to first-line chemo-immunotherapy (complete or partial response, or stable disease) and also received radiotherapy of primary lesions with radiation dose of over 40 Gy, with or without radiotherapy of metastatic lesions before the first disease progression. RESULTS: A total of 72 eligible patients were identified. With median follow-up duration of 14.6 (range, 7.1-34.8) months, median progression-free survival (PFS) and overall survival (OS) were 13.5 (95 % CI,10.4-NA) months and 31.8 (95 % CI, 23.0-NA) months, respectively. Median duration from initiation of chemo-immunotherapy to radiotherapy was 2.9 (range, 0-15.1) months. Besides lower tumor burden as a significant factor of better treatment outcome, radiation dose ≥ 50 Gy was associated with superior PFS, while OS might be mainly related to tumor response to the induction chemo-immunotherapy. A low incidence of Grade 3 or above treatment-related adverse events were observed (19 %), and no treatment-related death occurred. CONCLUSION: Our multi-center retrospective study showed survival benefit brought by early involvement of radiotherapy after first-line chemo-immunotherapy for patients with locally advanced or metastatic ESCC. However, further investigation is warranted in future prospective, controlled trials to assess the value of radio-immunotherapy in advanced or metastatic ESCC.