Objective: The treatment of advanced head and neck squamous cell carcinoma (HNSCC) with induction chemotherapy before radiation therapy has become more acknowledged over the last few years. The aim of our study was to find out, if histopathological parameters of the untreated primary tumor in HNSCC e.g. initial primary tumor grade, proliferation index, glucose transporter protein 1 (GLUT-1)expression could be possibly related to therapy response. Sequential 18F-FDGPET/CT imaging before and after induction chemotherapy and resulting 18F-FDGuptake was used as a surrogate for therapy response and compared to patient outcome.
Materials and Methods: 21 patients with advanced HNSCC treated by induction chemotherapy as first-line therapy were consecutively enrolled in this study. Defined responders (standardized uptake value (SUV) decrease > 75%) and non-responders (SUV decrease < 25%) were correlated to initial tumor grade (well, moderately, poorly differentiated) and other histopathological parameters including mitotic index, regression score and the expression of the GLUT-1 receptor for possible response predictive factors. Further, patient outcome was evaluated especially regarding survival.
Results: No significant correlation (p=0.472) could be found between response and histological grading (moderately or poorly differentiated). There was no significant difference between the SUV response and composition of chemotherapy (p=0.465),overall cycles (p=0.407), T-stage (p=0.557) or location of primary tumor (p=0.054). After a mean follow-up of 12 months, 6 patients were dead of disease, of which 5 had been classified as partial or non-responders and only one as a complete responder by 18F-FDG-PET/CT.
Conclusion: Since metabolic response was not correlated to initial histological parameters, response to chemotherapy can not be predicted by histopathological parameters alone. However, 18F-FDG-PET/CT seems to be a useful imaging protocol to monitor therapy response and may help to define therapy decision after induction chemotherapy.