Preoperative diagnoses and identification rates of unexpected gallbladder cancer

Unexpected gallbladder cancer (UGBC) is sometimes found in the resected gallbladder of patients during or after surgery. Some reports have indicated UGBC identification rates for all gallbladder surgeries, but scarce data are available for the UGBC identification rates for specific gallbladder diseases. The present study was performed to clarify UGBC rates and the factors suspicious for UGBC categorized according to preoperative diagnoses, in patients undergoing laparoscopic cholecystectomy (LSC).

We recorded data for all LSC surgeries performed in the Department of Surgery, Sada Hospital, Japan since 1991, and analyzed the 28-year data. We used the chi-square test and Kaplan-Meier analysis for this retrospective case-control study.

The UGBC identification rate was 0.69% (63/9186 patients). The UGBC identification rates categorized according to the preoperative diagnoses were 1.3% (13/969) for acute cholecystitis, 2.4% (16/655) for benign tumor, 2.0% (28/1383) for chronic cholecystitis or cholecystitis, and 0.054% (3/5585) for cholecystolithiasis. The percentage of older patients (≥ 60 years) was significantly higher in UGBCs compared with cases finally diagnosed as benign in each group categorized according to the preoperative diagnoses (p≤0.0014), except for cholecystolithiasis. In cases pre-diagnosed as benign tumor, UGBCs were associated with higher rates of thickened gallbladder wall compared with benign tumor (69.2% vs. 27.9%, respectively; p = 0.0011). UGBCs pre-diagnosed as acute cholecystitis had higher T2-T4 rates (100% vs. 64.3%, respectively; p<0.05) and lower survival rates (p = 0.0149) than UGBCs pre-diagnosed with chronic cholecystitis.

UGBC identification rates depend on the preoperative diagnosis and range from 0.054% to 2.4%. Older age (≥ 60 years) could be related to UGBC, and a pre-diagnosis of acute cholecystitis might indicate more advanced cancer compared with a pre-diagnosis of chronic cholecystitis.