Pancreatic ductal adenocarcinoma: is there a survival difference for R1 resections versus locally advanced unresectable tumors? What is a "true" R0 resection?

OBJECTIVE: Patients who undergo an R0 resection of their pancreatic ductal adenocarcinoma (PDAC) have an improved survival compared with patients who undergo an R1 resection. It is unclear whether an R1 resection confers a survival benefit over locally advanced (LA) unresectable tumors. Our aim was to compare the survival of patients undergoing an R1 resection with those having LA tumors and to explore the prognostic significance of a 1-mm surgical margin.
METHODS: Clinicopathologic data from a pancreatic cancer database between January 1993 and July 2008 were reviewed. Locally advanced tumors had no evidence of metastatic disease at exploration.
RESULTS: A total of 1705 patients were evaluated for PDAC in the Department of Surgery. Of the 1084 (64%) patients who were surgically explored, 530 (49%) were considered unresectable (286 locally unresectable, 244 with distant metastasis). One hundred fifty-seven (28%) of the resected PDACs had an R1 resection. Patients undergoing an R1 resection had a slightly longer survival compared with those who had locally advanced unresectable cancers (14 vs 11 months; P < 0.001). Patients with R0 resections had a favorable survival compared with those with R1 resections (23 vs 14 months; P < 0.001), but survival after resections with 1-mm margin or less (R0-close) were similar to R1 resections: both groups had a significantly shorter median survival than patients with a margin of greater than 1 mm (R0-wide) (16 vs 14 vs 35 months, respectively; P < 0.001).
CONCLUSIONS: Patients undergoing an R1 resection still have an improved survival compared with patients with locally advanced unresectable pancreatic adenocarcinoma. R0 resections have an improved survival compared with R1 resections, but this survival benefit is lost when the tumor is within 1 mm of the resection margin.