Hypoxia imaging with [18F]HX4 PET in squamous cell head and neck cancer: a pilot study for integration into treatment planning

Background: Radical chemoradiotherapy is the primary treatment for head and neck cancers in many hospitals. Tumour hypoxia causes radiotherapy resistance, and is an indicator of poor prognosis for patients. Identifying hypoxia to select patients for intensified or hypoxia-modified treatment regimens is therefore of high clinical importance. Patients and Methods: We evaluated hypoxia in a group of patients with newly diagnosed squamous cell head and neck cancer using the hypoxia-selective radiotracer [18F]HX4. Patients underwent a single [18F]HX4 PET/CT scan prior to beginning chemoradiotherapy.Results: Three out of eight patients recruited were scanned with [18F]HX4. Two out of three had pre-treatment [18F]FDGPET/CT scans available for review. [18F]HX4 tumour uptake varied between patients, with tumour to mediastinal ratios ranging from1 to3.5. Conclusions: The spectrum of [18F]HX4 uptake in this small series of patients exemplifies the difference in oxygenation profiles between histologically similar tumours. Performing an additional PET scan with [18F]HX4 prior to chemoradiotherapy treatment was logistically challenging in a routine setting, and therefore validation of its clinical impact should be the focus of future studies