Intraoperative electron beam irradiation for patients with unresectable pancreatic carcinoma.

Since 1978 we have used electron beam intraoperative radiation therapy (IORT) to deliver higher radiation doses to pancreatic tumors than are possible with external beam techniques while minimizing the dose to the surrounding normal tissues. Twenty-nine patients with localized, unresectable, pancreatic carcinoma were treated by electron beam IORT in combination with conventional external radiation therapy (XRT). The primary tumor was located in the head of the pancreas in 20 patients, in the head and body in six patients, and in the body and tail in three. Adjuvant chemotherapy was given in 23 of the 29 patients. The last 13 patients have received misonidazole (3.5 mg/M2) just prior to IORT (20 Gy). At present 14 patients are alive and 11 are without evidence of disease from 3 to 41 months after IORT. The median survival is 16.5 months. Eight patients have failed locally in the IORT field and two others failed regionally. Twelve patients have developed distant metastases, including five who failed locally or regionally. We have seen no local recurrences in the 12 patients who have been treated with misonidazole and have completed IORT and XRT while 10 of 15 patients treated without misonidazole have recurred locally. Because of the shorter follow-up in the misonidazole group, this apparent improvement is not statistically significant. Fifteen patients (52%) have not had pain following treatment and 22 (76%) have had no upper gastrointestinal or biliary obstruction subsequent to their initial surgical bypasses and radiation treatments. Based on the good palliation generally obtained, the 16.5-month median survival, and the possible added benefit from misonidazole, we are encouraged to continue this approach.