Effects of hyperoxygenation on FDG-uptake in head-and-neck cancer

Purpose: Tumor hyperoxygenation results in high response rates to ARCON (accelerated radiotherapy with carbogen and nicotinamide). The effect of hyperoxygenation on tumor metabolism using [F-18]fluorodeoxyglucose (FDG) positron emission tomography (PET) was investigated. Methods: Within one week, FDG-PET was performed without and with hyperoxygenation by carbogen breathing and/or nicotinamide administration in 22 patients, eligible for ARCON for head-and-neck cancer. Maximum standardized uptake values (SUVmax) in both scans and the relative change were calculated in the primary tumor and in normal muscle. Results: Alteration of the tumor oxygenation state induced profound, but variable, metabolic changes (median Delta SUVmax -4%; range -61% to +30%). Metabolism in normal muscle was not affected. In three patients who did not achieve local tumor control, the SUVmax after hyperoxygenation differed less than 5% change as compared to baseline, whereas 13 of the 16 patients with local tumor control showed a larger difference (p < 0.05). Conclusion: Given the heterogeneous response pattern of nicotinamide and carbogen on FDG-uptake in head-and-neck carcinoma, the prognostic significance of semiquantitative FDG-PET before and after hyperoxygenation remains uncertain and requires confirmation in larger clinical studies before introducing the procedure as a predictive tool for oxygenation modifying treatments. (c) 2006 Elsevier Ireland Ltd. All rights reserved.