Exocrine pancreatic function following intraoperative irradiation of the canine pancreas

Abstract

Twenty-four beagles received intraoperative irradiation (IORT) with 6 meV electrons to the pancreas and the duodenum. Intraoperative irradiation doses of 17.5 to 40 Gy were given. Billroth I1 gastrojejunostomy was done to bypass the irradiated duodenum. Six control dogs received only the Billroth I1 surgery. Two weeks postoperatively, irradiated dogs were given 50 Gy of 6 MV X radiation (externalbeam radiation [EBRTJ) to the pancreas and duodenum in 2 Gy fractions over a 5-week period. Dogs were monitored clinically and exocrine pancreatic function was evaluated using an N-benzoyl-l-tyrosylpara-aminobenzoic acid (BT-PABA) test between 3 and 135 days postoperatively. Necropsies were performed on the dogs at 135 days postoperatively. The degree of gross pancreatic atrophy in the irradiated group was dose related. The mean percentage of normal acinar cells correlated with IORT doses and para-aminobenzoic acid (PABA) values (P < 0.1). Weight loss was significantly greater in the irradiated dogs compared to the control (P < 0.05) and the mean percentage of body weight loss correlated with the mean PABA values (P < 0.01). In this study, the use of the BT-PABA test to evaluate progressive exocrine pancreatic function following IORT and EBRT showed an expected trend. A progressive decrease in exocrine pancreatic function in the irradiated dogs as indicated by plasma PABA levels may have been partly due to late radiation damage to acinar cells, secondary to vascular and ductular damage. At 135 days postoperatively none of the dogs showed clinical signs of exocrine pancreatic insufficiency and the plasma PABA levels were within the normal presurgical range. The progressive decrease in plasma PABA levels indicated a potential for the late development of exocrine pancreatic insufficiency. The BT-PABA test could be useful for evaluating the progressive decrease in exocrine pancreatic function and residual radiation injury to the pancreas. Because the exocrine deficiency can be managed with replacement therapy, pancreatic injury may not be a serious complication after doses of less than 30 Gy IORT with 50 Gy EBRT. Data from this study are in agreement with previous clinical and experimental reports that the duodenum is dose-limiting for IORT. Doses of 20 Gy IORT or less plus 50 Gy EBRT for treatment of carcinoma of the pancreas may not result in serious long-term complications due to radiation injury of the duodenum.Cancer 62:1091-1095, 1988.NTRAOPERATIVE RADIOTHERAPY (IORT) for pancre-I atic adenocarcinoma is considered to be one of the most promising treatment modalities for this fatal disReports from several centers have indicated that the use of IORT for pancreatic adenocarcinoma increased the median survival time of patients as well as alleviated pain associated with this disease. The duodenum is considered to be dose-limiting in IORT for pancreatic adenocar~inoma.~ Intraoperative radiotherapy doses in excess of 20 Gy resulted in duodenal ~lceration.~ Duodenal fibroses and stenosis commonly occurred after IORT and for th...

Dosimetric comparison of intensity modulated and volumetric arc radiation therapy for gastric cancer

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Intraoperative radiotherapy for pancreatic adenocarcinoma

“…Table 1 shows an overall summary of the recommended doses of IORT for abdominal and retroperitoneal organs in humans. When IORT doses as high as 40 Gy were delivered to the canine pancreas, pancreatic exocrine dysfunction or marked histological changes were not noted after short‐term follow‐up (≤4 months) 10,21. Corroborative data on the pathological observations in human pancreas after IORT in several clinical reports clearly show that endocrine and exocrine function is maintained in pancreatic cancer patients, whose life expectancy is typically 6–18 months.…”

Intraoperative radiotherapy for resectable and unresectable pancreatic carcinoma

“…Hemorrhage from the upper gastrointestinal tract has been reported,9,11,12,13 however, so irradiation of the duodenum should be minimized. The upper limit of the intraoperative radiation dose in animals is considered to be 20–30 Gy for normal duodenum14,15 and 30 Gy for normal pancreas 14…”