Impact of Portal Vein Involvement from Pancreatic Cancer on Metastatic Pattern After Surgical Resection

The present study aims to evaluate the long-term outcome and metastatic pattern of patients who underwent resection of a pancreatic ductal adenocarcinoma (PDAC) with portal or superior mesenteric vein (PV/SMV) resection.

Patients who underwent a partial pancreatoduodenectomy or total pancreatectomy for PDAC between 2005 and 2015 were retrospectively analyzed. Three subgroups were generated, depending on PV/SMV resection (P⁺) and pathohistological PV/SMV tumor infiltration (I⁺): P⁺I⁺, P⁺I⁻, and P⁻I⁻. Statistical analysis was performed using the R software package.

The study cohort included 179 patients, 113 of whom underwent simultaneous PV/SMV resection. Thirty-six patients (31.9 %) had pathohistological tumor infiltration of the PV/SMV (P⁺I⁺), and were matched with 66 cases without PV/SMV infiltration (P⁻I⁻). The study revealed differences in overall median survival (11.9 [P⁺I⁺] vs. 16.1 [P⁺I⁻] vs. 20.1 [P⁻I⁻] months; p = 0.01). Multivariate survival analysis identified true invasion of the PV/SMV as the only significant, negative prognostic factor (p = 0.01). Whereas the incidence of local recurrence was comparable (p = 0.96), the proportion of patients with distant metastasis showed significant differences (75 % [P⁺I⁺] vs. 45.8 % [P⁺I⁻] vs. 54.7 % [P⁻I⁻], p = 0.01). Furthermore, the median time to progression was significantly shorter if the PV/SMV was involved (7.4 months [P⁺I⁺] vs. 10.9 months [P⁺I⁻] vs. 11.6 months [P⁻I⁻]). Initial liver metastases occurred in 33 % of the patients.

True invasion of the PV/SMV is an independent risk factor for overall survival, and is associated with a higher incidence of distant metastasis and shorter progressive-free survival. Radical vascular resection cannot compensate for aggressive tumor biology.