High-dose intraoperative radiotherapy for unresectable pancreatic cancer

PURPOSE: The results of high-dose intraoperative radiotherapy (IORT) and/or external beam radiotherapy (EBRT) for unresectable pancreatic cancer were analyzed to evaluate the possible advantages of IORT in combination with EBRT. METHODS AND MATERIALS: Between 1983 and 1993, 115 patients with unresectable adenocarcinoma of the pancreas (53 with non-Stage IV disease and 62 with Stage IV disease) were treated with EBRT + IORT (55 patients), EBRT alone (44 patients), or IORT alone (16 patients). In non-Stage IV patients, the use of EBRT alone was due to the unavailability of IORT and the use of IORT alone was due to refusal of EBRT. The IORT dose was 30-33 Gy and the EBRT dose was 40-60 Gy. A historical control group comprised of 101 patients undergoing palliative surgery alone was also analyzed. RESULTS: Both non-Stage IV and Stage IV patients receiving EBRT with or without IORT had a better prognosis than the nonirradiated historical controls. Among non-Stage IV patients, the median survival of the EBRT + IORT group (8.5 months) and the EBRT group (8 months) was similar, although survival from 12 to 18 months was higher in the former group (38% vs. 10% at 12 months, p = 0.018, and 19% vs. 0% at 18 months, p = 0.023). In Stage IV patients, the prognosis was not influenced by the type of radiotherapy. Multivariate analysis revealed that a pretreatment carbohydrate antigen (CA) 19-9 level < 1000 U/ml was associated with better survival. In non-Stage IV patients with a CA 19-9 level < 1000 U/ ml, EBRT + IORT appeared to produce a better survival than EBRT alone (p = 0.047). This was supported by multivariate analysis. CONCLUSION: High-dose IORT + EBRT may be more effective than EBRT alone in patients with unresectable but localized pancreatic cancer and a low CA 19-9 level.