Neoadjuvant chemoradiotherapy using moderately hypofractionated intensity-modulated radiotherapy for borderline resectable pancreatic cancer : Outcomes and prognostic radiotherapeutic factors.

Purpose: To evaluate the outcome and prognostic factors for borderline resectable pancreatic cancer (BRPC) patients treated with neoadjuvant chemoradiotherapy using moderately hypofractionated intensity-modulated radiotherapy (NAC-MH-IMRT).

Methods: Patients with BRPC treated with NAC-MH-IMRT at 42 Gy in 15 fractions between February 2013 and June 2021 were evaluated. The overall survival (OS), progression-free survival (PFS), cumulative incidence of locoregional failure and distant metastases, association dose-volume indices, Evans grade for pathological response, and toxicities were evaluated.

Results: A total of 66 patients met the inclusion criteria, and the median follow-up period was 23.9 months. In all, 48 patients underwent pancreatectomy, and margin-negative resection was achieved in 44 patients (91.7%). The median survival and PFS times were 34.8 months and 12.0 months, respectively, for the whole cohort. The 2‑year cumulative incidences of locoregional recurrence and distant metastases in the resected group were 25.7 and 52.8%, respectively. From the Mann-Whitney U test, the minimum dose of the primary gross tumor volume (GTV_min) of the group with Evans grade ≥ 2b was statistically higher than that of the other group (38.6 Gy vs. 37.3 Gy, p = 0.005). However, this was not associated with reduced cumulative incidence of locoregional failure. No patient had grade ≥ 3 acute gastrointestinal toxicity.

Conclusion: NAC-MH-IMRT for BRPC resulted in good survival outcomes and margin-negative resection rates. High GTV_min was associated with good pathological response; however, improvement of local control requires further investigation.