Positive vein groove margin does not affect survival in patients undergoing pancreatoduodenectomy for early stages of pancreatic ductal adenocarcinoma

Abstract

Presenter: Manish Ahuja MBBS, DNB | University Hospitals Birmingham NHS Trust Background: The prognostic significance of portal/superior mesenteric vein (PV/SMV) groove involvement after pancreaticoduodenectomy (PPPD) for pancreatic ductal adenocarcinoma (PDAC) is controversial. Following adoption of the reporting guidelines by the Royal College of Pathologists (R1: tumour margin < 1mm), R1 reporting rates have increased which are considered to impact the overall survival. The aim of this study was to investigate the significance of R1 vein groove margin on overall (OS) and disease-free survival (DFS) after pancreaticoduodenectomy (PD) for early stage pancreatic ductal adenocarcinoma (PDAC). Methods: This is a single centre retrospective study including all resections performed for resectable and borderline with venous only involvement (BR-V) PDAC of the head and uncinate process over a 10-year period (2011-2020). Statistical investigation was performed with descriptive statistics and Kaplan Meier and univariate and multivariate Cox regression survival analysis. Results: Two hundred patients underwent PD for resectable (n = 117, 59%) or BR-V (n = 83, 41%) tumours. Vein resection was performed in 102 (51%) cases. Pathological staging of the tumours was pT1 11 (6%), pT2 122 (61%) and pT3 67 (33%) cases; and pN0 18 (9%) pN1 101 (51%) pN2 81 (40%) cases. Clear surgical margins were observed in 35 (17%) cases. In 34 (17%) cases the vein groove margin was the only positive margin reported (VG+). Median follow-up was 14 months (range: 1-83). OS was significantly better in cases with clear margins (p = 0.006) (Picture 1a). No difference in OS was identified between VG+ only patients and those with negative margins (p = 0.129) or those with multiple sites of margin positivity (p = 0.172). Cox regression analysis did not identify VG+ only margin as an independent predictor of OS (Table 1). In a multivariate model investigating the surgical margins separately, the posterior, SMA and pancreas transection margins, as well as perineural invasion and adjuvant chemotherapy were identified as independent predictors of OS. DFS was significantly better if surgical margins were clear (p = 0.014) (Picture 1b). A trend to worse DFS was identified in patients with VG+ margin only compared to those with negative margins (p = 0.058). No difference in DSF was observed between VG+ only patients and those with multiple sites of margin positivity (p = 0.608). Cox regression analysis did not identify VG+ only margin as an independent predictor of DFS (Table 1). In a multivariate model investigating the surgical margins separately, the SMA margin was the only margin along with adjuvant chemotherapy that independently predicted DFS. Conclusion: Vein groove margin positivity doesn’t affect OS but may affect DFS after PD in patients with resectable and BR-V PDAC. In contrast, the posterior and pancreas transection margins along with PNI were identified as independent risk factors for OS. The SMA margin and adjuvant chemotherapy were independent factors for both OS and DFS.