Relevance of positive resection margins in ductal pancreatic adenocarcinoma and prognostic factors

Introduction: Currently, R1 resection is defined by the presence of tumor cells within <1mm of the resection margin. The main aim of this study was to analyze the impact of positive margins (R1) on survival outcomes in pancreatic cancer.

Methods: We performed a retrospective analysis with multivariate regression analysis of a prospective database from 2008-2017, which included resection margin status, expanded resection margin (R1<1mm), vascular resection, lymphatic involvement, surgical complications, tumor differentiation grade and adjuvant treatment.

Results: A total of 80 patients were analyzed: 42 (52%) R1; 38 (48%) R0. No differences were found in the composition of the two groups except for the vascular resection, which was more frequent in the R1 group: 12 (21%) vs 2 (3%). Overall survival in the R0 group was 19 months vs 24 months in the R1 group (p=0.13). Wide R1 (R1<1mm) had an overall survival of 21 months versus 31 months in wide R0 (p=0.55). In the multivariate analysis, only lymph node involvement (p=0.02, HR=2.88), tumor differentiation (p=0.02, HR=3.2) and adjuvant therapy (p<0.01; HR=0.21) were found to be factors related to survival.

Conclusions: R1 resection is not an independent risk factor. Lymph node involvement, differentiation grade and adjuvant treatment are prognostic factors. The benefit of expanding the resection margins should be demonstrated. More studies are needed to assess the impact of the resection margin.