Intraoperative radiotherapy for unresectable pancreatic cancer: a multi-institutional retrospective analysis of 144 patients.

Purpose: To retrospectively analyze the results of intraoperative radiotherapy (IORT) + external beam radiotherapy (EBRT) for unresectable pancreatic cancer.

Methods And Materials: The records of 144 patients treated with IORT, with or without, EBRT were reviewed. One hundred and thirteen patients (78.5%) were treated with IORT + EBRT and 114 patients (79.2%) were treated in conjunction with chemotherapy. The median doses of IORT and EBRT were 25 Gy and 45 Gy, respectively. The median follow-up of all 144 patients was 9.6 months (range, 0.5-69.7 months).

Results: At the time of this analysis, 131 of 144 patients (91.0%) had disease recurrences. Local progression was observed in 60 patients (41.7%), and the 2-year local control (LC) rate in all patients was 44.6%. Patients treated with IORT, with or without, EBRT had significantly more favorable LC (2-year LC, 50.9%) than those treated with IORT without EBRT (p = 0.0004). The 2-year overall survival (OS) rate and the median survival time in all 144 patients were 14.7% and 10.5 months, respectively. Patients treated with chemotherapy had a significantly favorable OS than those treated without chemotherapy (p < 0.0001). On univariate analysis, chemotherapy use alone had a significant impact on OS and on multivariate analysis; chemotherapy use was a significant prognostic factor. Late gastrointestinal morbidity of National Cancer Institute-Common Terminology Criteria Grade 3 was observed in 2 patients (1.4%).

Conclusion: IORT + EBRT yields a relatively favorable LC rate for unresectable pancreatic cancer with low frequency of severe late toxicity, and IORT combined with chemotherapy conferred a survival benefit compared with IORT without chemotherapy.