Usefulness of 3′-Deoxy-3′-18F-Fluorothymidine PET for Predicting Early Response to Chemoradiotherapy in Head and Neck Cancer

This study compared the utility of 3'-deoxy-3'-F-18-fluorothymidine PET (F-18-FLT PET) with that of F-18-FDG PET for assessment of the early locoregional clinical outcomes of chemoradiotherapy for head and neck squamous cell carcinomas. Methods: From May 2006 to September 2010, 28 patients with head and neck squamous cell carcinomas underwent F-18-FLT and F-18-FDG PET before radiation therapy (RT), 4 wk after the initiation of RT, and 5 wk after completion of RT. PET images were evaluated qualitatively for regions of focally increased metabolism and were analyzed in relation to residual accumulation and local disease control. Results: During RT, F-18-FLT uptake decreased more significantly than F-18-FDG uptake. F-18-FLT accumulations disappeared in 34 of 54 lesions (63%), and negative predictive value was 97%. F-18-FDG PET during RT also had a high negative predictive value (100%), but only 9 lesions (16%) showed complete absence of accumulation. The specificity and overall accuracy of F-18-FLT PET were significantly higher than those of F-18-FDG PET both during and after RT. In particular, high significance was attributable to the results of the evaluations of primary lesions. There were significant differences in 3-y local control between the residual-accumulation and no-accumulation groups on both posttreatment F-18-FLT PET (P < 0.0001) and posttreatment F-18-FDG PET (P = 0.0081). Conclusion: F-18-FLT PET during AT and early follow-up facilitates the selection of optimal further therapy and the prediction of outcomes.