PATTERNS OF FAILURE IN GROSSLY RESECTED PANCREATIC DUCTAL ADENOCARCINOMA TREATED WITH ADJUVANT IRRADIATION +/- 5-FLUOROURACIL

Purpose: Analyze patterns of failure, survival, and tolerance in patients with totally resected ductal adenocarcinoma of the pancreas treated with adjuvant irradiation alone or combined with chemotherapy. Methods and Materials: The records of 29 patients treated with radiotherapy following curative resection of pancreas cancer at the Mayo Clinic were retrospectively reviewed. Twenty-two (76%) patients underwent a subtotal pancreatectomy (Whipple procedure), six (21%) a total pancreatectomy, and one (3.5%) a distal pancreatectomy. Twenty-six (90%) had lesions located in the head of the pancreas and three (10%) were located either in the body or tail. Twelve (41%) of the tumors were histologic Grade 3, 15 (52%) Grade 2, and two Grade 1. Contiguous invasion of adjacent tissues or organs was found in fifteen patients (52%) and seventeen (59%) had lymph node involvement. Greater than 75% of patients received more than 45 Gy, with a median dose of 54 Gy, and twenty-seven (93%) patients received concomitant 5-fluorouracil chemotherapy. Results: The median survival was 22.8 months and the 2-year survival 48%. When survival was compared with that achieved with surgery alone in our institution, data suggested a doubling in both median and long-term survival with the addition of adjuvant treatment. Eighty-three percent of patients experienced tumor relapse with seventeen of 29 (59%) developing either liver metastases or peritoneal spread. In three patients, tumors recurred locally; one of one with microscopic residual disease after resection and two of 28 (7%) with negative margins (one of the two was treated with inadequate radiation portals). Patients tolerated adjuvant treatment with minimal acute toxicity consisting mostly of vomiting or nausea which, were controlled with medication in all patients. Chronic toxicity was acceptable; while 5 of 29 (17%) developed some form of possible treatment related complication, only one patient (3.5%) developed a small bowel obstruction. Conclusion: These results corroborate data in previous studies which have shown a survival benefit when adjuvant irradiation plus 5-fluorouracil is used in patients with completely resected ductal adenocarcinoma of the pancreas. The patterns of failure indicate that post-operative adjuvant treatment can effectively control disease locally but that future survival improvements will be achieved only by reducing the incidence of liver and peritoneal metastases.