BACKGROUND Whether to classify "advanced (subserosal layer or greater invasion)" biliary carcinoma centered in the cystic duct (BCCD) as gallbladder carcinoma (GBC) or perihilar cholangiocarcinoma (PHCC) remains unclear. METHODS The clinicopathological features and overall survival (OS) of patients with advanced BCCD were examined through a comparison with those of patients with advanced PHCC and with GBC. RESULTS 290 patients were classified as 199 PHCC, 44 GBC, and 47 BCCD. Patients with BCCD (median, 23 months) had significantly worse OS than those with PHCC (44 months, p = 0.030). OS of patients with BCCD, all of whom were classified as pT3 or pT4 by the American Joint Committee on Cancer (AJCC) classification of GBC, was similar to 27 patients with pT3 or pT4 GBC (23 months, p = 0.840). When the patients with BCCD were classified by the AJCC classification of PHCC, 36 were classified as pT2. OS among the patients with BCCD classified as pT2 by the PHCC classification (29 months) was significantly worse than that among patients classified as pT2 PHCC (48 months, p = 0.040). CONCLUSION These findings suggest that advanced BCCD is appropriately classified as a subtype of GBC because it can grow through the serosa.