Radiographic portal or superior mesenteric vein invasion is an independent prognostic factor in non-metastatic pancreatic ductal adenocarcinoma: A missing block of clinical T staging?

Abstract

BackgroundVenous invasion is not included in the pancreatic ductal adenocarcinoma (PDAC) staging, and its correlation with prognosis remains unclear. We evaluated the prognostic impact of radiographic portal/superior mesenteric vein (PV/SMV) invasion, and its possibility of complementing T staging. MethodsWe identified patients with non-metastatic PDAC using our institutional cohort, and divided them according to PV/SMV invasion at imaging, defined as >180-degree tumor-vessel interface or contour deformity. We conducted Cox proportional hazard regression, and compared survival in the original and 1:1 propensity score matched datasets. ResultsWe identified 454 patients [PV/SMV(+): 172; PV/SMV(−): 282]. In the multivariate analysis, PV/SMV invasion, age (≥70 years), performance status, tumor size (2–4, >4 cm), lymph nodes >4, and arterial invasion was correlated with prognosis. The PV/SMV(+) group had a shorter overall survival (OS) than the PV/SMV(−) group in the original (14.4 vs. 20.9 months; P < 0.001) and matched datasets (14.3 vs. 17.2 months; P = 0.009). Among patients without arterial invasion (cT1–cT3), the PV/SMV(+) group had a shorter OS (15.9 vs. 21.2 months; P = 0.002). Moreover, their OS did not differ from that of patients with arterial invasion (cT4) (15.9 vs. 14.4 months; P = 0.907). Patients with vessel (artery/vein) invasion had a shorter OS than those without vessel invasion (14.5 vs. 21.2 months; P < 0.001). ConclusionsRadiographic PV/SMV invasion in non-metastatic PDAC was correlated with a poor prognosis. It could identify a group with shorter OS among patients without arterial invasion (cT1–cT3). It is suggested that inclusion of PV/SMV invasion in clinical T4 criteria should be considered.