Intraoperative radiotherapy for pancreatic cancer: 30-year experience in a single institution in Japan.

Purpose: To analyze retrospectively the results of intraoperative radiotherapy (IORT) with or without external beam radiotherapy (± EBRT) for localized pancreatic cancer in the past three decades and to analyze prognostic factors by multivariate analysis.

Methods And Materials: Records for 322 patients with pancreatic cancer treated by IORT ± EBRT in Tohoku University Hospital between 1980 and 2009 were reviewed. One hundred ninety-two patients who had no distant organ metastases or dissemination at the time of laparotomy were enrolled in the present study.

Results: Eighty-three patients underwent gross total resection (R0: 48 patients, R1: 35 patients), and 109 patients underwent only biopsy or palliative resection. Fifty-five patients underwent adjuvant EBRT, and 124 underwent adjuvant chemotherapy. The median doses of IORT and EBRT were 25 and 40 Gy, respectively. The median follow-up period was 37.5 months. At the time of the analysis, 166 patients had disease recurrence, and 35 patients had local failure. The 2-year local control (LC) and overall survival (OS) rates were 71.0% and 16.9%, respectively. Comparison of the results for each decade showed that OS was significantly improved decade by decade (2-year: 25.0% vs. 18.8% vs. 4.2%, p < 0.001). Multivariate analysis showed that degree of resection (R0-1 vs. R2, hazard ratio = 1.97, p = 0.001) and adjuvant chemotherapy (yes vs. no, hazard ratio = 1.54, p = 0.028) had significant impacts on OS. Late gastrointestinal morbidity of Common Terminology Criteria for Adverse Events version 3.0 grade 4 or 5 was observed in four patients.

Conclusion: Excellent local control for pancreatic cancer with few cases of severe late toxicity was achieved by using IORT. OS of patients with pancreatic cancer treated by IORT ± EBRT improved significantly decade by decade. Multivariate analysis showed that degree of resection and adjuvant chemotherapy had significant impacts on OS.