The role of FDG PET/CT in patients with colorectal cancer metastases

Introduction: Growing subsets of patients with metastatic colorectal cancer (CRC) are being considered for treatment with curative intent. Accurate re-staging of patients with potentially resectable hepatic or pulmonary metastases is therefore crucial for optimal management. This article presents data to assess the role of 18-fluoro-deoxyglucose ((18)FDG) positron emission tomography/computed tomography (PET/CT) in metastatic CRC. Materials and Methods: A total of 341 patients with potentially resectable liver and/or pulmonary CRC metastases underwent (18)FDG PET/CT between 1st April 2007 and 31st August 2008 at our unit. Of these, 157 patients fulfilled the inclusion criteria and were included in this retrospective assessment. Imaging and clinical histories of these patients were evaluated. Findings on PET/CT were compared with pre-PET/CT conventional imaging and overall impact on patient management was assessed. The PET/CT results were confirmed either with histological comparison where available or with serial imaging follow up. Results: On a lesion to lesion basis, PET/CT when compared with pre-PET/CT conventional imaging in patients with metastatic liver and lung lesions had a Spearman correlation coefficient of 0.8 and P value < 0.0001 in both subgroups. PET/CT upstaged disease in 33.1% (52/157), down staged disease in 24.9% (39/157) and was in agreement with pre-PET/CT conventional imaging in the remaining 42% of patients (66/157). Based on PET/CT results surgery was averted in 33.8% patients (53/157). PET/CT had a sensitivity of 87.1%, specificity of 88.0%, positive predictive value of 97.4%, negative predictive value of 56.4% and an overall accuracy of 87.3% in assessing metastatic disease. Conclusion: Assessment with (18)FDG PET/CT has a significant impact on the management of CRC patients with hepatic and pulmonary metastases.