Fundamental studies on efficacy of intraoperative radiotherapy on pancreatic carcinomas transplanted into the pancreas of hamsters

Efficacy of intraoperative electron beam radiotherapy (IOER) on N-nitrosobis (2-hydroxypropyl) amine (BHP) induced pancreatic carcinomas transplanted into the pancreas of the Syrian golden hamsters were studied and the following results were obtained. 1. Selective electron beam application to the carcinoma transplanted into the pancreas of hamsters was accomplished using an electron beam collimator. 2. Intra-pancreatic transplantability of BHP-induced serially transplantable subcutaneous pancreatic carcinomas was 100%. 3. Intra-pancreatic transplanted pancreatic carcinomas disappeared in 2 out of 19 hamsters (11%) by 10 Gy irradiation and 7 out of 15 (47%) by 20 Gy irradiation given 2 weeks after intra-pancreatic transplantation. 4. In contrast to the linear growth of tumor size in the non-irradiated group, the tumor size showed an electron dose-dependent reduction in the irradiated group. 5. Histologically, marked necrosis was noted in the irradiated group, and the intensity of necrosis differed between the 10 Gy and 20 Gy groups. 6. Direct invasion of tumor to the stomach, small intestine, large intestine, liver and abdominal wall was noted. Its incidence tended to decrease as the electron dose increased (5/19 or 26% for the control group, 4/19 or 21% for the 10 Gy group, and 1/17 or 6% for the 20 Gy group), although the difference was not statistically significant. 7. The incidences of liver and lymph node metastasis were not different between the non-irradiated and the irradiated groups. These results suggest that selective IOER on BHP-induced pancreatic carcinomas has an effectiveness to kill cancer cells in hamsters.