['In the present study we undertook a retrospective analysis of gallbladder carcinoma to assess whether histologically determined hepatic artery (HA) invasion and portal vein (PV) invasion can be considered prognostic factors.', 'Seventy-one patients who had undergone radical resection for gallbladder carcinoma between 1995 and 2008 at University of Tsukuba were selected from the database for analysis. Patients who required extended surgery for para-aortic lymph node metastasis were also included. Correlation between invasion of the HA and the PV and prognosis and other clinicopathologic factors were analyzed.', 'There were two postoperative deaths among the 71 patients. Pathological invasion of the HA was confirmed in 16 (22.5%) cases and PV invasion was confirmed in 15 patients. Patients with invasion of the HA had a significantly poorer prognosis than those without HA invasion (P < 0.0001). Additionally, in univariate analysis, gender (male), positive para-aortic lymph node metastasis, PV invasion, and HA invasion were identified as significant poor prognostic factors. In multivariate analysis, only HA invasion was an independent prognostic factor (Odds Ratio 0.323; P = 0.029).'] Is invasion of the hepatic artery a crucial predictor of poor outcomes in gallbladder carcinoma?