Characterization of co-existing adenoma and adenocarcinoma in comparison with conventional adenocarcinoma of gallbladder

Background: Gallbladder adenoma-adenocarcinoma is a rare pathway of gallbladder malignancy, while little is known about the clinicopathological characteristics and surgical outcomes about co-existing adenoma and adenocarcinoma of gallbladder (CAAG). Methods Between January 2010 and December 2020, 73 CAAG patients who underwent curative surgical resection at West China Hospital of Sichuan University were retrospectively reviewed. Results The clinicopathological characteristics of CAAG were distinct from conventional gallbladder adenocarcinoma (GBAC). Patients with CAAG were less likely to have liver parenchyma invasion (P = 0.010), and more commonly to have smaller tumor sizes (P = 0.040), early T stage (P < 0.001) and lower CA19-9 level (P < 0.001). Compared with conventional GBAC patients, CAAG patients showed significantly better overall survival (OS) (36.0 vs 25.0 months; P = 0.001). Multivariate analysis confirmed tumor size (P = 0.047), T stage (P = 0.007), surgical margin (P < 0.001) and histological subtypes (P = 0.037) as independent prognostic factors influencing OS of patients with CAAG. Furthermore, compared with none-papillary CAAG, papillary CAAG patients showed even worse survival outcome (30.0 vs 40.0 months, P = 0.005). Conclusion CAAG always has mild biological behaviors and better survival outcomes after curative surgery. Larger tumor size, advanced T stage and positive surgical margin were associated with inferior OS in patients with CAAG. The histological subtype of papillary CAAG patients showed the worse survival outcome.