Outcomes of Intraoperative Radiotherapy for Locally Advanced Adenocarcinoma of the Esophagogastric Junction After Neoadjuvant Therapy: A Single-Arm, Phase 1 Trial From the Chinese National Cancer Center.

Background: The role of intraoperative radiotherapy (IORT) for adenocarcinoma of the esophagogastric junction (AEG) remains uncertain. Therefore, a prospective phase 1 trial was conducted to assess the safety and feasibility of IORT for locally advanced AEG.

Methods: The study enrolled patients with AEG at stages II-IVA from January 2019 to September 2019. Eligible patients received esophagectomy and a single fraction of electron beam radiotherapy. The primary endpoint of the study was a safety profile for IORT. Additionally, survival outcomes and the locoregional recurrence rate (LRR) were compared between the non-IORT and IORT cohorts using propensity score-matching.

Results: For 15 (93.8 %) of the 16 patients in the study, R0 resection was successfully achieved, with only one patient undergoing R1 resection. A total postoperative complication morbidity rate of 43.8 % (7/16) was observed, with major complications (Clavien-Dindo classification ≥3) in 12.5 % of the cases (2/16). Total treatment-related adverse events were reported for seven patients (43.8 %, 7/16). After matching, a lower LRR was observed in the IORT group than in the non-IORT group (0 % [0/12] vs 33.3 % [4/12]; p = 0.028). However, the two groups did not differ significantly in 3-year progression-free survival (PFS: IORT [50.9 %] vs non-IORT [53.4 %]; p = 0.93) or 3-year overall survival (OS: IORT [58.3 %] vs IORT [72.9 %]; p = 0.23).

Conclusions: The current study demonstrated favorable feasibility and safety of IORT for locally advanced AEG. Although IORT is beneficial for improving local control, it may not prolong PFS or OS for patients with locally advanced AEG. A phase 2 trial is warranted for further validation of these outcomes.