R0 Versus R1 Resection Matters after Pancreaticoduodenectomy, and Less after Distal or Total Pancreatectomy for Pancreatic Cancer

Objective: The aim of this study was to decipher the true importance of RO versus R1 resection for survival in pancreatic ductal adenocarcinoma (PDAC). Summary of Background Data: PDAC is characterized by poor survival, even after curative resection. In many studies, RO versus R1 does not result in different prognosis and does not affect the postoperative management. Methods: Pubmed, Embase, and Cochrane databases were screened for prognostic studies on the association between resection status and survival. Hazard ratios (HRs) were pooled in a meta-analysis. Furthermore, our prospective database was retrospectively screened for curative PDAC resections according to inclusion criteria (n = 254 patients) between July 2007 and October 2014. Results: In the meta-analysis, R1 was associated with a decreased overall survival [HR 1.45 (95% confidence interval, 95% CI 1.37-1.52)] and disease-free survival [HR 1.44 (1.30-1.59)] in PDAC when compared with R0. Importantly, this effect held true only for pancreatic head resection both in the meta-analysis [R0 >= 0 mm: HR 1.21 (1.05-1.39) vs R0 >= 1 mm: HR 1.66 (1.46-1.89)] and in our cohort (R0 >= 0 mm: 31.8 vs 14.5 months, P < 0.001; R0 >= 1 mm, 41.2 vs 16.8 months; P < 0.001). Moreover, R1 resections were associated with advanced tumor disease, that is, larger tumor size, lymph node metastases, and extended resections. Multivariable Cox proportional hazard model suggested G3, pN1, tumor size, and R1 (0 mm/1 mm) as independent predictors of overall survival. Conclusion: Resection margin is not a valid prognostic marker in publications before 2010 due to heterogeneity of cohorts and lack of standardized histopathological examination. Within standardized pathology protocols, R-status' prognostic validity may be primarily confined to pancreatic head cancers.