Assessment of hypoxic subvolumes in laryngeal cancer with (18)F-fluoroazomycinarabinoside ((18)F-FAZA)-PET/CT scanning and immunohistochemistry.

Abstract

(18)F-fluoroazomycinarabinoside ((18)F-FAZA) is a promising hypoxia radiopharmaceutical agent with outstanding biokinetic parameters. We aimed to determine the accuracy of (18)F-FAZA-PET/CT scan in detecting hypoxic regions within the tumor using immunohistochemical markers in a pilot study. Eleven patients with primary or recurrent laryngeal squamous cell carcinoma were indicated for total laryngectomy (TLE). Patients underwent (18)F-FAZA-PET/CT scan before TLE. Hypoxic regions inside the laryngeal tumor were determined. After TLE, regions with high uptake on (18)F-FAZA-PET scan were selected for immunohistochemical examination for exogenous (pimonidazole) and endogenous (HIF1α, CA-IX and GLUT-1) hypoxia markers. To assess the accuracy of (18)F-FAZA-PET scanning, radiopharmacon accumulation was related with immunohistochemical expression of hypoxia markers. Inter- and intratumoral heterogeneity of tumor hypoxia was observed on (18)F-FAZA-PET scan. Nine of the eleven tumors were hypoxic with (18)F-FAZA-PET. Hypoxia could also be detected with pimonidazole, HIF1α, CA-IX and GLUT-1 expression in some tumors. No clear association was observed between (18)F-FAZA uptake and hypoxia markers. This pilot study could not prove the accuracy of (18)F-FAZA-PET in determining hypoxic subvolumes in laryngeal cancer. Further study is required to investigate the benefit of (18)F-FAZA-PET imaging in radiotherapy planning.