Objective: To review our experience with cholangiocarcinoma with superficial spread, to clarify its clinical features, and to discuss treatment strategies. Summary Background Data: Most of the previous reports on cholangiocarcinoma with superficial spread were case reports. Little is known about this type of cholangiocarcinoma. Methods: The medical records of 471 patients with cholangiocarcinoma who underwent resection (35 1 perihilar and 120 distal cancers) were retrospectively reviewed, focusing on superficial spread, which was defined as noninvasive cancer extension of more than 20 rum. Results: Superficial spread was found in 69 (14.6%) of 471 patients, and its length was 54 +/- 19 mm. Histologically, papillary and well differentiated adenocarcinomas were observed more frequently in cholangiocarcinomas with superficial spread (C+SS), compared with those without superficial spread (C-SS). Histologic indexes showing tumor aggressiveness, including lymphatic, venous, and perineural invasions, were lower in C+SS, and all factors of tumor staging (pT, pN, and pM) were less advanced in C+SS than in C-ss. Regarding surgical procedure, a combined hepatectomy and pancreatoduodenectomy was indicated in 26 (37.7%) of the 69 patients with C+SS, but in only 25 (6.2%) of the 402 patients with C-SS. Positivity of the proximal ductal margin was higher in C+SS than in C-SS (18.8% vs. 11.9%), although this was not statistically significant. All positive proximal ductal margins in C+SS were because of carcinoma in situ, whereas invasive cancer was the main reason for positivity in C-SS. Survival (excluding 29 in-hospital deaths) was significantly better in the patients with C+SS than in those with C-SS (5- and 10-year survival rates; 48.8% and 19.6% vs. 26.8% and 16.6%, P = 0.0009). Survival was comparable between the patients with a negative ductal margin and those with a positive margin with carcinoma in situ. On multivariate analysis, the presence or absence of superficial spread was not identified as a prognostic factor. Conclusions: C+SS is associated with less advanced, slower growing tumors and better survival compared with C-SS. In many cases of C+SS, the survival does not depend on the complete resection of all the superficial spread but on the stage of the main lesion.