Splenic vein tumor thrombosis is a major prognostic factor in distal pancreatic adenocarcinoma

Background The prognostic value of splenic vessel involvement in distal pancreatic adenocarcinoma remains controversial. The aim of the study was to assess its prognostic relevance in a large multicenter cohort. Methods Patients who underwent pancreatosplenectomy for distal pancreatic adenocarcinoma were identified from 5 pancreatic surgical centers. A pathology review of the surgical specimens was performed to assess splenic vessel involvement, defined as invasion of the vessel’s adventitia or deeper, and confirm the presence of splenic vein tumor thrombosis. Prognostic factors associated with overall and relapse-free survival were evaluated. Results 149 patients underwent upfront surgery. Splenic vascular involvement was observed in 69 of them (46.3%). A parietal infiltration of the splenic artery or splenic vein was observed in 26 (17.5%) and 49 patients (32.8%), respectively. A pathologic tumor thrombosis of the splenic vein was identified in 22 patients (14.8%) and associated with larger tumors (>20 mm) (P = .023), more perineural (P = .017), and lymphovascular (P = .002) invasion, and more positive lymph node (P = .001). After a median follow-up of 50.8 months (95% confidence interval: 44.3–57.3), the cumulative 5-year overall and relapse-free survival were 46.2% and 33%, respectively. In multivariate analysis, in addition to lymph node metastasis (hazard ratio = 1.8; 95% confidence interval [1.1–3.1]; P = .023) and perineural invasion (hazard ratio = 3.5; 95% confidence interval [1.3–9.7]; P = .016), presence of splenic vein tumor thrombosis was the only splenic vascular involvement that affected independently the overall survival (HR = 2.3; 95% confidence interval [ 1.3–4.3]; P = .006). Conclusion In resectable distal pancreatic adenocarcinoma, a pathologic tumor thrombosis of the splenic vein is an independent prognostic factor of overall survival. To define the perioperative oncological strategy, a preoperative evaluation of splenic vessel involvement and thrombosis is needed.