DAHANCA 35 is two parallel conducted, but separate randomized studies, within the same trial (DAHANCA 35D and DAHANCA 35X) by the Danish Head-Neck Cancer Study Group (DAHANCA). In patients with squamous cell carcinoma of the pharynx or larynx planned for primary radiotherapy a proton and a photon doseplan is prepared. If proton radiotherapy reduces the anticipated absolute risk of dysphagia >= grade 2 (DAHANCA scale, DAHANCA 35D) or severe xerostomia >= grade 4 (EORTC Head-Neck 35, DAHANCA 35X) more than 5%, the patient is randomised to either proton therapy or photon therapy, 2:1. The anticipated risk of xerostomia and dysphagia is estimated using Normal-Tissue Complication Models (NTCP). Patient are analysed according to the primary endpoint (dysphagia and/or xerostomia) after which they were enrolled. DAHANCA 35D is expected to enroll 360 patients and DAHANCA 35X 240 patients (in total 600 patients).
Patients with squamous cell carcinoma of the pharynx or larynx and an anticipated benefit of proton radiotherapy in reducing the risk of late dysphagia or xerostomia are randomized to proton or photon radiotherapy (2:1)