Definition of microscopic tumor clearance (r0) in pancreatic cancer resections

Abstract

To date, curative resection is the only chance for cure for patients suffering from pancreatic ductal adenoacarcinoma (PDAC). Despite low reported rates of microscopic tumor infiltration (R1) in most studies, tumor recurrence is a common finding in patients with PDAC and contributes to extremely low long-term survival rates. Lack of international definition of resection margins and of standardized protocols for pathological examination lead to high variation in reported R1 rates. Here we review recent studies supporting the hypothesis that R1 rates are highly underestimated in certain studies and that a microscopic tumor clearance of at least 1 mm is required to confirm radicality and to serve as a reliable prognostic and predictive factor.

Figure 1

Pancreatoduodenectomy specimens: The posterior surface and the medial margin are the main sites of microscopic tumor infiltration [4,16,17,18]. Drawings by Lukas Bauer.

Figure 2

Pancreatoduodenectomy specimen with tumor infiltration (R1): Direct invasion of tumor cells within 1 mm of the medial margin (green).