Aims and objectives: This retrospective study aims at correlating the pre- and post-therapy maximal standardized uptake values (SUVmax) of the whole-body 18-flourodeoxy glucose positron emission tomography (FDG-PET) scan with tumor response in patients with head and neck squamous cell cancer undergoing chemoradiotherapy.
Materials and methods: Data for this retrospective study were taken from the clinical records of 20 evaluable head and neck cancer patients who had availed treatment and evaluation at our institute during the previous year (March 2017-April 2018). All these above-mentioned patients had undergone chemoradiation at our center for locally advanced squamous cell carcinoma of the head and neck and had undergone pre- and post-therapy whole-body FDG PET scan. The posttherapy PET-computed tomography (CT) was advised after 8 weeks' postcompletion of therapy. During the PET CT scan, images were acquired 1 h after injection of FDG. Pre- and post-therapy SUVmax were recorded and correlated with immediate treatment response.
Results: The mean pretherapy SUVMax of the primary tumor was 10.27 ranging from 4.5 to 26.17. The mean pretherapy SUVMax of the node was 5.34 ranging from 0 to 17.9. The mean time of recording the posttherapy SUVMax was 3 months (range 2-5 months). The mean posttherapy SUVMax of the primary tumor was 1.05 ranging from complete metabolic response to 6.4. The mean posttherapy SUVMax of the node was 0.7 ranging from complete metabolic response to 5.43. The statistical analysis based on Wilcoxon-Signed Rank test revealed a statistically significant difference in the pre- and post-therapy SUVmax values for both primary tumor (P < 0.001) and regional node (P = 0.001). Majority of patients (n = 15) showed clinical remission; however, five patients had progressive disease at the time of evaluation.
Conclusion: Although the retrospective study revealed that complete responders had a statistically significant reduction in the posttherapy SUVmax in comparison to the pretherapy SUVmax it failed to identify a cutoff value for pretherapy SUVmax which could predict the probable outcome of therapy. In view of the same further prospective studies need to be conducted with larger patient numbers including various other tumor metabolic markers for greater clarity.
Keywords: 18-flourodeoxy glucose positron emission tomography; Chemoradiotherapy; head and neck cancer; squamous cell carcinoma.