Purpose: To compare the diagnostic efficacies of (18)F-FLT and (18)F-FDG PET/CT in non-small-cell lung cancer (NSCLC), focusing on the correlation between FLT and FDG tumour uptake and tumour cell proliferation as indicated by the cyclin D1 labelling index.
Methods: A total of 31 patients with NSCLC underwent FLT and FDG PET/CT scanning followed by surgery. PET/CT images were compared with the pathology. Tumour cell proliferation was assessed by cyclin D1 immunohistochemistry.
Results: The sensitivities of FLT and FDG PET/CT for the primary lesion were 74% and 94%, respectively (p=0.031). For N staging, 77% patients were correctly staged, 6% overstaged, 16% understaged by FLT, while the values for FDG were 77%, 16% and 6%, respectively. The sensitivity, specificity, accuracy, and positive predictive value with FLT for lymph nodes were 65%, 98%, 93% and 89%, respectively, and 85%, 84%, 84% and 52% with FDG (p<0.01).Tumour SUV of FLT was significantly correlated with the cyclin D1 labelling index (r=0.644; p<0.01), but the SUV of FDG was not significantly correlated (r=0.293; p>0.05).
Conclusion: In terms of N staging, FLT PET/CT resulted in understaging of more patients but overstaging of fewer patients, and for regional lymph nodes showed better specificity, accuracy and positive predictive value than FDG PET/CT in NSCLC. Tumour FLT uptake was correlated with tumour cell proliferation as indicated by the cyclin D1 labelling index, suggesting that further studies are needed to evaluate the use of FLT PET/CT for the assessment of therapy response to anticancer drugs.