Background: A considerable percentage of gallbladder cancers are accompanied by superficial cancer spread adjacent to the main tumor, therefore cholecystectomy for early gallbladder cancer must be performed carefully to avoid leaving cancer cells at the surgical margins.
Methods: Thirty-two patients with gallbladder cancer invading no more than perimuscular connective tissue underwent surgical resection at our medical center. After the operation, resected specimens were investigated macroscopically and microscopically to clarify the clinicopathological features and the risk factors of superficial cancer spread.
Results: Sixty-six percent of all cases (21 cases) had superficial cancer spread. Comparison between the cases having superficial cancer spread and the cases without it revealed that the macroscopic morphology of the primary tumor and the depth of cancer invasion in the gallbladder wall were significantly different between the two groups. Furthermore, multivariate analysis indicated that 'superficial raised type' in macroscopic morphology was an independent predictive factor for having superficial cancer spread. Superficial cancer spread from the main tumor located in the neck of the gallbladder grows predominantly in the direction of the fundus. More advanced gallbladder cases were accompanied by more extensive superficial spread.
Conclusions: Superficial cancer spread is frequently observed adjacent to the gallbladder cancer, especially in the superficial raised type. A negative margin should be confirmed by intraoperative frozen section histology while performing cholecystectomy.