Prognostic implications of superior mesenteric vein/portal vein resection and histologic venous invasion in BR/LA PDAC after neoadjuvant therapy

BACKGROUND: Superior mesenteric vein/portal vein (SMV/PV) resection is often required in borderline resectable or locally advanced pancreatic ductal adenocarcinoma (BR/LA PDAC) after neoadjuvant therapy (NAT), but its prognostic relevance and the role of histopathologic venous invasion remain unclear. METHODS: We retrospectively analyzed BR/LA PDAC patients undergoing pancreatectomy after NAT and compared perioperative and oncologic outcomes between patients requiring SMV/PV resection and those with venous preservation. Subgroup analyses assessed histopathologic venous invasion within the resection cohort. Kaplan-Meier analysis was used to evaluate overall survival (OS) and disease-free survival (DFS), and Cox regression was used to identify factors associated with OS. RESULTS: Among 117 patients, 65 (55.6%) underwent SMV/PV resection and 52 (44.4%) had venous preservation. Although baseline demographic and clinical characteristics were broadly similar, the resection cohort showed greater local anatomic and operative complexity. Postoperative morbidity and mortality did not differ significantly between groups. Median OS was similar between the SMV/PV resection and preservation groups (16.0 vs. 22.0 months; P = 0.965), as was median DFS (10.0 vs. 12.0 months; P = 0.843). Within the resection cohort, histopathologically confirmed venous invasion was associated with significantly shorter OS (8.3 vs. 24.0 months; P < 0.0001) and DFS (5.0 vs. 17.0 months; P = 0.0002), whereas survival was similar between patients with venous preservation and those who underwent resection without venous invasion. R0 resection was associated with longer OS and DFS than R1 resection. In multivariable analysis, R1 resection and histopathologically confirmed SMV/PV invasion were independently associated with poorer OS. CONCLUSIONS: In our cohort, patients requiring SMV/PV resection had outcomes broadly comparable to those with venous preservation despite greater operative complexity. Histopathologic venous invasion and R1 status were associated with worse OS and DFS. These findings support interpreting SMV/PV resection primarily as a marker of local anatomic disease extent rather than an independent adverse prognostic factor.