Evaluation of the therapeutic effects and recurrence for head and neck cancer after chemoradiotherapy by FDG-PET.

Abstract Objective The purpose of this study was to detect early stage recurrence or a residual tumor after chemoradiotherapy by FDG-PET. Methods A total of 51 head and neck cancer lesions in 27 patients were examined—including primary sites and metastatic lymph nodes. The therapeutic effects were evaluated by visual inspection, pre-treatment SUV, post-treatment SUV and % change in SUV. Results No local recurrence was observed in 37 of the lesions, while recurrence or a residual tumor was observed in the other 14 lesions after therapy. A significant difference was found between the two groups regarding the post-treatment SUV and the % change in SUV. Taking the post-treatment SUV of 3 and the % change of 60 as a cut-off value, a significant difference was thus found between the recurrence cases and non-recurrence cases. When all lesions were divided into two groups—including the post-treatment SUV > 3 and the % change in the SUV   60 group, the overall accuracy was 88.2% (45/51). Therefore, it is more useful to predict the prognosis after chemoradiotherapy by a combined analysis of the post-treatment SUV and the % change in SUV. According to the post-treatment PET period, namely, within 4 weeks and from 5 to 15 weeks after treatment, the accuracy was 85.7% (24/28) and 91.3% (21/23), respectively ( p  = 0.5385). Conclusion The results suggest that it may be possible to predict the recurrence even at 4 weeks after treatment. Therefore, the use of a semi-quantitative analysis of FDG-PET between the pre-treatment and post-treatment findings is thus considered to be helpful in choosing the optimal therapy and for making an accurate prognosis.