Incidental and Non-Incidental Gallbladder Carcinoma: A Retrospective Comparison of Clinicopathological Characteristics and Survival Outcomes

Background: Incidental gallbladder carcinoma (IGBC) refers to malignancies detected during histopathological examination following cholecystectomy performed for benign indications. Although IGBC is generally diagnosed earlier, its impact on survival remains unclear. We compared the clinicopathological characteristics and overall survival outcomes of patients with IGBC and non-incidental gallbladder carcinoma (NIGBC) and evaluated independent prognostic factors affecting survival. Materials and Methods: A total of 69 patients histopathologically diagnosed with gallbladder carcinoma between January 2008 and December 2019 were retrospectively reviewed. Patients were grouped by mode of diagnosis as IGBC (n=40) or NIGBC (n=29). Clinical, surgical, and histopathological characteristics were compared. Overall survival was analyzed using the Kaplan-Meier method, and prognostic factors were evaluated using univariable and multivariable Cox regression analyses. Results: Among the 12,938 cholecystectomies, IGBC was identified in 40 cases (0.31%). The median tumor size was significantly smaller in the IGBC group than in the NIGBC group (19 mm vs. 35 mm, p<0.001). In addition, early pT stage (pT1–2) and early disease stage (Stage I–II) were significantly more frequent in the IGBC group (p<0.001 for both), as were the presence of gallstones and the rate of laparoscopic surgery (p<0.001 for both). No significant difference in overall survival was observed between the groups (log-rank p=0.589). In the multivariable analysis, age, advanced pT stage, and positive surgical margins were identified as independent factors affecting overall survival. Incidental diagnosis was not an independent prognostic factor. Conclusion: Although patients with IGBC were diagnosed with smaller tumors and at an earlier pathological stage, incidental diagnosis alone was not associated with improved overall survival. In this study, prognosis was primarily associated with tumor stage and the adequacy of surgical resection. Our findings support the importance of routine histopathological examination following cholecystectomy for benign indications to facilitate the early detection of occult gallbladder carcinoma and appropriate treatment planning.