The prognostic impact of differentiation at the invasive front of biliary tract cancer

BackgroundThe invasive front of tumor can provide prognostic information in many cancers. We investigated the prognostic morphological factors at the invasive front including tumor differentiation (Dif(inv)) and tumor budding (Bud) in biliary tract cancer (BTC). MethodsThe resected specimen from the 299 BTC patients were examined. Intrahepatic cholangiocarcinoma, extrahepatic cholangiocarcinoma, gallbladder cancer, and ampulla of Vater cancer were found in 16%, 48%, 17%, and 19%, respectively. Dif(inv)grade (G) 3 and Bud foci 5 were found in 47% and 10%. Tumor with Dif(inv)G3 showed the high frequencies of Bud, vascular invasion (Ve) and nodal metastasis (LN) compared to tumor with Dif(inv)G1/2 (Bud: 21% vs 0%, Ve: 71% vs 50%, LN: 52% vs 36%). Multivariate analysis revealed that the independent predictors were Dif(inv)G3 (HR: 1.71), Bud foci 5 (HR: 2.14), Ve (HR: 1.56) and LN (HR: 2.59) in overall survival and were positive resection margin (HR: 1.71), Dif(inv)G3 (HR: 1.75), Ve (HR: 1.50), and LN (HR: 2.19) in relapse free survival. ConclusionPoor differentiation at the invasive front of tumor was associated with poor prognosis and early relapse in BTC patients.