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

Tumor hyperoxygenation results in high response rates to ARCON (accelerated radiotherapy with carbogen and nicotinamide). The effect of hyperoxygenation on tumor metabolism using [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) was investigated.

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 (SUV(max)) in both scans and the relative change were calculated in the primary tumor and in normal muscle.

Alteration of the tumor oxygenation state induced profound, but variable, metabolic changes (median DeltaSUV(max) -4%; range -61% to +30%). Metabolism in normal muscle was not affected. In three patients who did not achieve local tumor control, the SUV(max) 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).

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.