Factors predicting advanced disease in patients with incidentally detected gallbladder cancer: when to advise ¹⁸F-FDG PET-CT?

Incidentally detected gallbladder cancer (IGBC) constitutes a significant fraction of the gallbladder cancer burden. We investigated various parameters for association with increased risk of non-regional lymph nodal or distant metastases in IGBC. The oncologist may thus be guided when to advise ¹⁸F-FDG PET-CT to exclude advanced disease before planning completion surgeries.

Data from 50 patients (36 females, 14 males) with IGBC who underwent ¹⁸F-FDG PET-CT scans were retrospectively analyzed. Logistic regression was used to identify independent predictors of distant metastases.

Distant metastatic disease was present in 29/50 (58%) patients on ¹⁸F-FDG PET-CT. 6/50 patients had only locoregional residual disease while 15/50 patients had no abnormal lesion. On univariate analysis, female gender (P = 0.012), pT2a or above extent (P = 0.003), lymphovascular invasion (P = 0.023), positive cystic duct margin (P = 0.022), local residual disease on CECT (P = 0.006) and regional lymph nodes on CECT (P = 0.022) were associated with distant metastases. On multivariate analysis, pT2a or above extent (P = 0.029, odds ratio = 10.9), lymphovascular invasion (P = 0.016, odds ratio = 19.5), local residual disease (P = 0.006, odds ratio = 60.5) and regional nodes on CECT (P = 0.02, odds ratio = 16.8) remained independent predictors of metastatic disease. In 12/50 (24%) patients, PET-CT detected additional lesions over CECT leading to a change of management in 10/50 (20%) patients.

¹⁸F-FDG PET-CT may be advised to exclude distant metastases in IGBC patients with any of the four predictive features, including T-stage pT2a or above, presence of lymphovascular invasion, and local residual or regional lymph nodal disease on CECT.