R1 resection in pancreatic cancer has significant impact on long-term outcome in standardized pathology modified for routine use

Abstract

The quality of a histopathologic workup after oncologic resection of pancreatic malignancies has changed the central role of surgery substantially for radical tumor clearance over the past years. The development of standardized protocols for pathologic workup increased the rate of R1 resections from around 20% up to 80%. In the present study, we investigated the incidence of R1 and its impact on survival after oncologic pancreatic resections using a standardized pathologic routine protocol. We performed 265 pancreatic resections from September 2003 to September 2010. Among 128 patients with malignant neoplasms, histology revealed ductal pancreatic adenocarcinoma in 97, ampullary cancer in 10, and distal bile duct cancer in 21 patients. Resected specimens were analyzed according to this improved standardized pathology protocol introduced in 2000. Follow-up data on overall and cancer-related survival, presence and site of tumor recurrence, and chemotherapy were obtained from 120 patients. Pancreatic resection comprised a pylorus-preserving or classical pancreaticoduodenectomy in 112, a distal pancreatectomy in 8, and a total pancreatectomy in 7 patients. In the overall series, 56 (44%) were classified R1 resections and 68 (43%) R0 resections, 3 patients with R2 resections were excluded, leaving 125 patients for analysis. In pancreatic adenocarcinoma, the rate of R1 was 51% (48/94). R1 resection involved most frequently the circumferential margin in 86% (48/125) of the total group and in 92% (44/48) in pancreatic cancer. Follow-up was performed after a median of 17 months (range, 1-85) postoperatively. Cancer-related death rate in R0 and R1-resected patients was 60% and 83% (P < .02) in all cancers (n = 117) and 66% and 80% in patients with pancreatic adenocarcinoma (n = 88). Median tumor-related survival in R0 and R1 resections was 22 (range, 4-85) vs 14 months (range, 2-48) in all cancers (P < .002), and 19 (range, 4-85) vs 14 months (range, 2-48) in pancreatic adenocarcinoma (P < .04). Kaplan-Meier survival analysis revealed a survival benefit after R0 resection in both all cancers (P = .002) and pancreatic adenocarcinoma (P < .02). The pattern of tumor recurrence had a greater rate of regional metastases in the R1 group (P < .05). Our 51% rate of R1 resections in ductal pancreatic carcinoma indicates a high quality standard of pathologic evaluation. The vast majority of R1 margins are located at the retroperitoneal dissection surface. Standardization of histopathologic analysis has a clinically relevant impact on survival after oncologic resection of pancreatic cancer and can be achieved by less extensive protocols.