Preneoplastic lesions in gallbladder cancer.

Background: Gallbladder cancer is an uncommon disease except in countries like Chile and areas of India and Japan. The knowledge regarding the etiology and mechanisms through which this neoplasia is developed is significantly less compared to other malignant tumors.

Results: The epithelial lesions involved in gallbladder carcinogenesis are dysplasia and adenomas that represent two biologically distinct carcinogenetic models. Dysplasia progresses to carcinoma in situ (CIS) and subsequently becomes invasive. Over 80% of invasive gallbladder cancers present areas adjacent to the CIS and epithelial dysplasia. Other authors have demonstrated adenomatous areas in carcinomas, or malignant transformation in an adenoma. The low incidence of gallbladder adenomas (0.14% of cholecystectomies) and the presence of adenomatous remnants in the neighboring mucosa to early carcinomas in less than 3% of the cases suggest the limited importance of this carcinogenic pathway. Epithelial dysplasia which is not associated with gallbladder cancer is observed in approximately 1% of cholecystectomies for symptomatic lithiasis. Metaplasia, dysplasia, and CIS are present in the mucosa adjacent to the cancer in 66%, 81.3%, and 69%, respectively. The average ages of patients with dysplasia not associated to cancer (51.9 years), early carcinomas (56.8 years), and advanced carcinomas (62.9 years) demonstrate a gradient which suggests the progression of these lesions.

Conclusions: From the morphological point of view, the dysplasia-carcinoma sequence is the most plausible carcinogenic pathway for gallbladder cancer, a process which would require a period of approximately 10 years.