Role of PETCT in locally advanced gall bladder cancer

Abstract

Background: Locally advanced gall bladder cancer (LAGBC) portends a grave prognosis. Its management entails a critical balance of choosing the patients who will benefit from radical and often morbid multimodality treatment. This study aims to study the role of 18F-FDG (Fluoro-deoxyglucose) PET (Positron emission tomography)CT in detecting metastatic disease and deciding treatment intent in patients with LAGBC. Materials and Methods: This is an audit of a prospectively maintained database of GBC . Patients found to have locally advanced (T3/4,N+) but non-metastatic disease on initial imaging i.e. Contrast Enhanced Computed Tomography (CECT)/ Magnetic Resonance Imaging (MRI) Scan underwent an additional PETCT for staging and the changes impacting treatment decision were recorded. Results: 103 patients with LAGBC underwent both CECT/MRI and PETCT. 48/103 (46.6%) were found to be upstaged to stage IV after PETCT. The most common metastatic site was retroperitoneal lymph nodes (12 patients, 11.7%) followed by liver( 11,10.7%). The mean interval between CT and PETCT was 19 days. 14 (13.6%) patients had equivocal findings on PET scan which needed tissue diagnosis out of which 10(71.4%) were subsequently confirmed to have metastatic disease. Equivocal findings on CT scan (OR 1.5), poorly differentiated histology (OR 1.89), T3/4 disease (OR 1.16,1.33) had a higher incidence of upstaging on PETCT however only the presence of loco-regional nodes had a statistically significant increased risk (OR 6.15, p 0.006). Conclusion: PETCT appears to be a valuable tool in the armamentarium of oncologists while evaluating patients of LAGBC because of its high yield of detecting metastatic disease especially in patients with locoregional nodes on cross sectional imaging.