Defining venous involvement in borderline resectable pancreatic cancer

Background: Pancreatic adenocarcinoma impinging the portal and/or superior mesenteric vein (PV-SMV) is classified as borderline resectable, and preoperative chemoradiation is recommended to increase the margin-negative resection rate. There is no consensus about what degree of venous impingement constitutes borderline resectability. Methods: All patients undergoing potentially curative pancreatectomy for pancreatic adenocarcinoma were reviewed. Venous involvement was classified by preoperative computed tomography according to Ishikawa types: (I) normal, (II) smooth shift without narrowing, (III) unilateral narrowing, (IV) bilateral narrowing, (V) bilateral narrowing with collateral veins. Results: From 1990-2009, 109 patients underwent resection of pancreatic adenocarcinoma involving the PV-SMV. Seventy-four patients received preoperative chemoradiation, whereas 35 did not. Patients who received preoperative therapy had a significantly longer median overall survival rate of 23 months compared with 15 months for patients without preoperative therapy (P = 0.001). Preoperative chemoradiation was associated with higher R0 resection rate and negative lymph nodes (both P < 0.0001) but did not affect the need for vein resection. When stratified by Ishikawa types, preoperative therapy was associated with improved overall survival among patients with types II and III but not types IV and V. Similarly, the correlation between preoperative therapy and R0 resection rate was observed only among patients with Ishikawa types II and III. Conclusions: Preoperative therapy for borderline resectable pancreatic adenocarcinoma is associated with higher margin-negative resection and survival rates in patients with Ishikawa type II and III tumors, defined as a smooth shift or unilateral narrowing of the PV-SMV. Patients with bilateral venous narrowing were less likely to benefit from preoperative treatment.