Patients aged 18 years and older with stage III , IVa , or IVb , previously untreated , measurable ( 10 mm for at least one dimension ) , locally advanced squamous-cell carcinoma of the head and neck ( non-nasopharygeal ) and an Eastern Cooperative Oncology Group performance status of 0-1 were randomly assigned ( 2:3 ) by an independent vendor to open-label chemoradiotherapy ( two cycles of cisplatin 100 mg/m ( 2 ) during radiotherapy ) or to radiotherapy plus panitumumab ( three cycles of panitumumab 9 mg/kg every 3 weeks administered with radiotherapy ) using a stratified randomisation with a block size of five .