Assessment of hypoxic subvolumes in laryngeal cancer with 18F-fluoroazomycinarabinoside (18F-FAZA)-PET/CT scanning and immunohistochemistry. Issue 1 (October 2015) - Bruine de Bruin, Leonie
Abstract: Background and purpose: 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. Patients and methods: 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. Results: 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. Conclusions: 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.