This single-center, non-randomized interventional dose-finding phase I trial evaluates the maximal tolerated boost dose with respect to dose limiting toxicities in patients with locally advanced head and neck squamous cell carcinoma (UICC stage III/IVB) with an indication for a primary radiochemotherapy. The primary aim of the trial is to define the maximal tolerated dose in an ADC-based subvolume using an adaptive SBRT-boost areal. Dose-escalated SBRT boost to ADC-high risk volume will be delivered once a week and is defined according to the the actual imaging immediately performed prior to delivery (real-time adaptive) i.e. it can vary from one week to another and it might also be reduced throughout the course of treatment (response adaptive). In case of complete disappearance of high-risk subvolumes sufficient large enough to boost (<5ml), no further ADC boost but only the floor-boost dose is given. The dose escalation of the ADC-high risk volume boost is graduated in four dose levels of 5x5 Gy, 5x5.5 Gy, 5x6 Gy, 5x6.5 Gy in a classical 3+3 dose-finding design where 3 patients per radiation dose level are enrolled. Primary endpoint is the dose limiting toxicity, any acute and late non-hematologic grade 4 or 5 related to the radiotherapy intervention, ≥ grade 3 CTC v.5. oral mucositis at 3 months after radiotherapy.
This Phase 1 dose-finding study investigates the maximal tolerated dose for a subsequent phase 2 trial testing MR-guided individualized response-adaptive dose prescription in HNC.