Patterns of Failure After Neoadjuvant Stereotactic Body Radiation Therapy or Fractionated Chemoradiation in Resectable and Borderline Resectable Pancreatic Cancer.

Objectives The goal of this study was to compare outcomes of patients with borderline and resectable pancreatic cancer treated with neoadjuvant stereotactic body radiation therapy (SBRT) versus fractionated chemoradiation. Methods Patients with borderline or resectable pancreatic cancer treated with neoadjuvant intent between November 2011 and December 2017 were reviewed. The SBRT volume/dose was 33 Gy in 5 fractions to gross tumor plus abutting vessel with or without 25 Gy in 5 fractions to pancreatic head/body and celiac/superior mesenteric artery. Fractionated chemoradiation volume/dose was 50.4 Gy in 28 fractions to gross tumor, superior mesenteric/celiac arteries, and enlarged lymph nodes with concurrent bolus 5-FU, leucovorin, oxaliplatin, irinotecan or gemcitabine/nab-paclitaxel. Failure patterns, local recurrence-free survival (LRFS), progression-free survival (PFS), and overall survival were assessed. Results Forty-three patients were reviewed (18 SBRTs and 25 fractionated). Among patients who underwent resection, patients treated with fractionated chemoradiation had improved LRFS (12-month LRFS, 86% vs 62%,P= 0.003) and PFS (median PFS, 23 months vs 11 months,P =0.006) compared with SBRT. There was no difference in overall survival. Conclusions Stereotactic body radiation therapy may result in inferior LRFS and PFS compared with fractionated chemoradiation, likely because of under coverage of high-risk vascular targets.