Is FDG –PET-CT A Valuable Tool in Prediction of Persistent Disease in Head and Neck Cancer

Objectives: To evaluate accuracy of FDG-PET CT in prediction of persistent disease in head and neck cancercases and to determine prognostic value of metabolic tumor response. Materials and
Methods: Between 2009and 2011, 46 patients with squamous cell carcinoma of head and neck receiving PET-CT were treated withdefinitive radiotherapy, with or without chemotherapy. There were 29 nasopharyngeal, 11 hypopharyngeal, 3oropharyngeal and 3 laryngeal cancer patients, with a median age of 50.5 years (range 16-84), 32 males and 14females. All patients were evaluated with PET-CT median 3-5 months (2.4-9.4) after completion of radiotherapy.
Results: After a median 20 months of follow up, complete metabolic response was observed in 63% of patients.Suspicious residual uptake was present in 10.9% and residual metabolic uptake in 26.0% of patients. The overallsensitivity, specificity, positive predictive value and negative predictive value of FDG-PET-CT for detection ofresidual disease was 91% and 81%, 64% and 96% respectively. Two year LRC was 95% in complete responderswhile it was 34% in non-complete responders.
Conclusions: FDG PET CT is a valuable tool for assessment oftreatment response, especially in patients at high risk of local recurrence, and also as an indicator of prognosis.Definitely more precise criteria are required for assessment of response, there being no clear cut uptake valueindicating residual disease. Futhermore, repair processes of normal tissue may consume glucose which appearas increased uptake in control FDG PET CT.