Radiotherapy for patients with locally advanced esophageal squamous cell carcinoma receiving neoadjuvant immunotherapy combined with chemotherapy.

ABSTRACT

With the success of immunotherapy in advanced esophageal cancer, neoadjuvant chemo-immunotherapy (CIT) is being increasingly used for local staged esophageal cancer, especially in the context of clinical trials, which brings similar pCR with neoadjuvant chemoradiotherapy and shows promising results. However, there is still a part of potentially operable patients can't undergo surgery after neoadjuvant chemo-immunotherapy. The follow-up treatment and prognosis of this population remain unclear. Patients pathologically diagnosed with ESCC, clinical stage T1-3N+M0 or T3-4aNanyM0 (AJCC 8th), PS 0-1 were retrospectively enrolled from 1/2020 to 6/2021 in Zhejiang Cancer Hospital. All patients firstly received PD-1 inhibitors plus chemotherapy (albumin paclitaxel, 260 mg/m2 on day 1 plus carboplatin AUC = 5 on day 1) every 3 weeks for 2-4 cycles. For those patients who did not receive surgery, definitive radiotherapy with 50.4 Gy/28F or 50 Gy/25F was adopted using VMAT, concurrent with chemotherapy or alone. The concurrent chemotherapy regimens included weekly TC (paclitaxel 50 mg/m2, d1, carboplatin AUC = 2, d1) or S1 (60 mg bid d1-14, 29-42). The survival outcomes and treatment toxicity were recorded and analyzed. A total of 56 eligible patients were finally identified from 558 patients who were treated in department of thoracic surgery, among all the patients, 25 (44.6%) received radiotherapy alone, and 31 (55.4%) received chemoradiotherapy after neoadjuvant CIT. The median follow-up was 20.4 months (interquartile range [IQR] 8.7-27 months). The median PFS and OS were 17.9 months (95% confidence interval [CI] 11.0-21.9 months) and 20.5 months (95% CI 11.8-27.9 months), respectively. In the subgroup analysis, the median OS was 26.3 months (95% CI 15.33-NA) for patients exhibiting partial response (PR) to CIT, compared to 17 months (95% CI 8.77-26.4) for those with stable disease (SD) or progressive disease (PD), yielding a hazard ratio (HR) of 0.54 (95% CI 0.27-1.06, P = 0.07). No significant difference was observed for patients received radiotherapy alone or chemoradiotherapy with HR = 0.73 (95% CI 0.72-2.6, P = 0.33). The most common Adverse events (AEs) observed during this study were anemia (98.2%), leukopenia (83.9%), thrombocytopenia (53.6%). AEs of grade ≥ 3 radiation-induced pneumonitis and esophagitis were 12.5% and 32.1%, especially, 6 patients (10.7%) died from esophageal fistula and 2 patients (3.6%) died from grade 5 pneumonitis. For local advanced ESCC patients after neoadjuvant CIT who did not receive surgery, definitive radiotherapy was an optional treatment strategy. However, those patients with no response to CIT also showed poor response to radiotherapy, and particular attention should be paid to treatment related toxicity, especially esophageal fistula.