Head and neck squamous cell cancer (stages III and IV) induction chemotherapy assessment: Value of FDG volumetric imaging parameters

Introduction To evaluate whether the change in the metabolic tumour volume (MTV) or total lesion glycolysis (TLG) of the primary tumour, before and after induction chemotherapy, predicts outcome for patients with advanced head and neck squamous cell cancer (SCC). Methods Twenty-eight patients with advanced (American Joint Committee on Cancer stage III and IV) head and neck SCC who underwent positron emission tomography (PET)/CT were included in this retrospective study. Primary tumour MTV and TLG were measured using gradient and fixed percentage threshold segmentations. Outcome endpoint was disease progression or mortality. Pearson correlation, Bland-Altman and receiver operator characteristic analysis were performed. Results The Pearson's correlation coefficients between percentage changes (pre- and post-induction chemotherapy) from gradient MTV (MTV_G) and the 38% SUV_max threshold MTV (MTV₃₈) was 0.96 and between MTV_G and the 50% threshold MTV (MTV₅₀) was 0.95 (P < 0.0001). The corresponding Pearson r between TLG_G and TLG₃₈ was 0.94 and between TLG_G and TLG₅₀ was 0.96 (P < 0.0001). The least bias was 1.89% (standard deviation = 25.30%) between the percentage changes of MTV_G and MTV₅₀. The areas under the curve for predicting progression or mortality were 0.76 (P = 0.03) for MTV_G and 0.82 for TLG_G (P = 0.009). Optimum cut points of a 42% reduction in MTV _G and a 55% reduction in the TLG_G predict event-free survival with a sensitivity of 62.5% and a specificity of 90% and a hazards ratio of 6.25. Conclusion A reduction in primary tumour MTV of at least 42% or in TLG of at least 55% after induction chemotherapy may predict event-free survival in patients with advanced head and neck SCC.