HIGH-DOSE INTRAOPERATIVE RADIOTHERAPY FOR UNRESECTABLE PANCREATIC-CANCER

Purpose: The results of high-dose intraoperative radiotherapy (IORT) a nd/or external beam radiotherapy (EBRT) for unresectable pancreatic ca ncer were analyzed to evaluate the possible advantages of IORT in comb ination with EBRT. Methods and Materials: Between 1983 and 1993, 115 p atients with unresectable adenocarcinoma of the pancreas 53 with non-S tage IV disease and 62 with Stage IV disease) were treated with EBRT IORT (55 patients), EBRT alone (44 patients), or IORT alone (16 patie nts). In non-Stage IV patients, the use of EBRT alone was due to the u navailability 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 his torical control group comprised of 101 patients undergoing palliative surgery alone was also analyzed. Results: Both non-Stage TV and Stage IV patients receiving EBRT with or without IORT had a better prognosis than the nonirradiated historical controls. Among non-Stage IV patien ts, 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 mon ths was higher in the former group (38% vs. 10% at 12 months, p = 0.01 8, 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/ mi, EBRT + IORT appeared to p roduce a better survival than EBRT alone (p = 0.047). This was support ed by multivariate analysis. Conclusion: High-dose IORT + EBRT may be more effective than EBRT alone in patients with unresectable but local ized pancreatic cancer and a low CA 19-9 level.