The predictive value of early assessment after one cycle of induction chemotherapy with 18F-FDG-PET/CT and DW-MRI for response to radical chemoradiotherapy in head and neck squamous cell carcinoma.
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To assess the predictive value of early assessment (after one cycle of induction chemotherapy (IC)) with (18)F-FDG-PET/CT and DW-MRI for subsequent response to radical chemoradiotherapy in locally advanced head and neck squamous cell carcinoma (HNSCC).20 patients with stage III-IVa HNSCC prospectively underwent (18)F-FDG-PET/CT and diffusion-weighted MRI (DW-MRI) before and 2 weeks following each cycle of IC (1st cycle - IC1, 2nd cycle - IC2). Response was assessed 3 months after completion of chemoradiotherapy with clinical examination, MRI and (18)F-FDG-PET/CT. Patients with persistent disease were classed as non-responders. Changes in functional and molecular imaging (FMI) parameters following IC1 were compared between responders and non-responders with Mann-Whitney U test. The significance threshold was set at P<0.05.Responders showed a significantly greater reduction in metabolic tumour volume (MTV)(P = 0.03) and total lesion glycolysis (TLG)(P = 0.04) following IC1 than non-responders. Responders also showed a tendency towards a larger, but statistically non-significant increase in apparent diffusion coefficient following IC1. There was no significant difference in the changes from baseline between the IC1 and IC2 for all FMI parameters indicating that most biological response to IC measured by (18)F-FDG-PET/CT and DW-MRI was observed early after the first cycle of IC.Our preliminary data indicate that the (18)F-FDG-PET/CT-derived MTV or TLG, acquired after IC1 are early predictive biomarkers for ultimate response to subsequent chemoradiotherapy. This enables identification of patients at risk of treatment failure at an early time-point, permitting treatment individualisation and consideration of alternative strategies such as radiotherapy dose-escalation or surgery.
Translational Molecular Imaging
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Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2016