Positive pancreatic neck margins-a telltale sign of complex biology.

HepatoBiliary Surg Nutr 2022;11(2):302-304 | https://dx.doi. org/10.21037/hbsn-21-553 Opinions remain divided on the definition, status and prognostic role of a positive pancreatic resection margin. The absence of a consensus definition for an R1 resection and the lack of a standard method to assess pancreatic resection specimens contribute to the ongoing controversy. These are some of the variables to consider when reviewing the literature on the role of resection margin status; a topic further complicated by the shifting landscape of pancreatic cancer management and the innate differences in institutional practices. Recently, Zhang and colleagues from the Massachusetts General Hospital (MGH) and the Verona Pancreas Institute published their joint experience on revising pancreatic neck margins found to be positive on intraoperative frozen section (FS) analysis. This is a crucial area to explore because it addresses two interlinked debates, the role of intraoperative FS analysis and the benefit of extending resections to revise positive neck margins. In their retrospective review, titled “Revision of the Pancreatic Neck Margin Based on Intraoperative Frozen Section Analysis in Patients Undergoing Pancreatectomy for Ductal Adenocarcinoma”, the authors observed that extended resection, via re-resection of a positive neck margin or conversion to a total pancreatectomy, was not only safe to perform but was also associated with improved overall survival (OS) (1). Their promising conclusions, however, are best appreciated when interpreted in light of other similar institutional experiences. Currently, there is no consensus definition for an R0 resection. The Union of International Cancer Control defines an R0 resection by the absence of tumor cells along the transection line on microscopic evaluation (2) This is the definition Zhang and colleagues used. In another widely adopted definition, an R0 resection is defined by the absence of tumor cells within 1 mm of the transection line on microscopic evaluation (3,4). The use of different definitions makes it difficult to compare study results from different groups (5). Despite the different definitions, published data revealed that the survival benefit of an R0 resection was independent of the used definition (6), which suggests that better identification of R1 status is more crucial than which definition is superior. Another challenge is standardizing the evaluation of pancreatic resection specimens and resection margins. Verbeke and colleagues outlined a standard protocol that evaluates resection specimens with a high degree of scrutiny. In their study, they described the six margins of a pancreaticoduodenectomy specimen, those being the anterior surface, the posterior and medial margins in contact with major abdominal vessels, the enteric margin, the bile duct margin and the pancreatic neck margin (3). They also described the circumferential resection margin and argued that a positive margin is defined by the presence of tumor cells within 1 mm of the closest margin (3). Interestingly, the rate of R1 resections increased as more specimens were evaluated using their standard protocol (3). Furthermore, many previously classified R0 resections were found to be R1 resections (3). More importantly, they observed that the most frequently involved margins were the posterior and medial margins whereas the pancreatic neck transection Editorial