Efficacy of primary tumour volume as a predictor of survival compared with size alone in pancreatic ductal adenocarcinoma

Tumour size (TSize) predicts outcome in pancreatic ductal adenocarcinoma (PDAC), but little is known regarding three-dimensional tumour volume (TVol) associations. We hypothesised that TVol would more accurately predict outcome following pancreatoduodenectomy (PD) for PDAC. Clinicopathological and outcome data was reviewed for all PDs performed in the Royal North Shore Hospital (St. Leonards, NSW, Australia), between April 2004 and November 2010, in patients whose three tumour dimensions were recorded (n=103). TVol was quantified using the ellipsoidal volume formula, 4/3π(r1xr2xr3), and was correlated with clinicopathological indices/outcome. Over a median follow-up time of 20.5 months, TVol failed to significantly predict post-resection mortality [odds ratio (OR), 1.0; 95% confidence interval (CI), 0.99-1.00; P=0.438)]. Neural invasion remained an overall independent predictor of mortality following multivariate analysis (OR, 3.94; 95% CI, 1.36-11.40; P=0.011). Patients with higher TVol were more likely to require a vascular resection (P=0.007), had longer surgical times (P<0.001), larger intraoperative blood losses (P=0.007) and a trend toward worse survival (P=0.068). TVol inclusion in a multivariate model resulted in a small improvement in mortality prediction versus TSize (14.9 vs. 14.7%). A higher TVol results in a more complex perioperative course. Although TVol improved the mortality prediction beyond simple TSize alone, this difference was not significant. Studies normalising TVol for body composition are required.