Tumor-positive resection margins reflect an aggressive tumor biology in pancreatic cancer

Background Resection margin status has been shown to impact outcomes for pancreatic adenocarcinoma (PAC), yet it remains unknown whether margin status is a reflection of tumor biology or surgical technique. Methods Two hundred eighty-three consecutive patients with pancreatic adenocarcinoma were identified in a prospectively maintained database. Only patients with R0 (n=207) or R1 (n=76) tumors were included. Each operative surgeon's first 50 cases were excluded to control for technical inexperience. Univariable and multivariable analyses of clinicopathologic and intra-operative factors were performed. Results The median follow-up for the cohort was 30.3 months with a median overall survival (OS) of 19.0 months. The R1 group had a higher rate of lymph node ratio >0.2 (41% vs. 25%; P=0.013), and more microvascular invasion (64% vs. 44%; P=0.007). R0 resections had both improved overall survival (22.7 months vs. 15.0 months, P=0.004) and disease free survival (13.5 months vs. 10.7 months, P=0.026). Factors independently associated with overall survival were microvascular invasion (HR 2.26; P=0.001), pre-existing pulmonary disease (HR 2.18, P=0.043), and cardiac disease (HR 1.78, P=0.033). Conclusion Factors associated with an R1 resection reflect a biologically more aggressive tumor, with a higher likelihood of microvascular invasion and increased positive lymph node ratio. J. Surg. Oncol. 2013;107:602607. (c) 2013 Wiley Periodicals, Inc.