Inclusion Criteria:

          -  American Joint Committee on Cancer (AJCC) TNM Stage III-IVa (T3N0-T4N0, and T1N1-T4N3)
             oropharyngeal squamous cell carcinoma (SCC) tumours

          -  Clinical multidisciplinary team decision to treat with primary curative cisplatin
             chemoradiotherapy

          -  No previous treatment including surgery, except node biopsies or diagnostic
             tonsillectomy

          -  Medically fit (ECOG 0, 1 or 2)

          -  Adequate cardiovascular, haematological, renal and hepatic function

          -  Age > 18 years

          -  Written informed consent given

          -  Using adequate contraception [male and female participants]. Must take contraceptive
             measures during, and for at least six months after treatment.

        Exclusion Criteria:

          -  Distant metastasis (i.e. AJCC TNM stage IVc disease)

          -  AJCC TNM Stage T1-2N0 disease

          -  Treated with primary radical surgery to the primary site (e.g. resection)

          -  Concurrent use of CYP3A4 inducers or inhibitors. [A standard course of dexamethasone
             or aprepitant for the prevention of cisplatin-induced nausea and vomiting is
             permitted]

          -  Serious cardiac illness or other medical conditions precluding the use of cisplatin or
             cetuximab [no history of clinically significant cardiac disease, serious arrhythmias,
             or significant conduction abnormalities; no uncontrolled seizure disorder; no active
             neurologic disease; no neuropathy greater than grade 1]

          -  Patients who have p16+ tumours who also have N2b, N2c or N3 nodal disease and whose
             lifetime smoking history is also more than 10 pack years (i.e. have both risk
             factors).

          -  Pregnant or lactating

          -  Previous treatment for any other cancer with cytotoxics, radiotherapy or anti-EGFR
             therapies

          -  Inadequate renal, haematological or liver functions [Absolute neutrophil count
             <1,500/mm3; platelet count <100,000/mm3; WBC <3,000/mm3; haemoglobin <9 g/dL.
             [Haemoglobin correction by transfusion permitted.] Bilirubin > 1.5 times upper limit
             of normal (ULN); alkaline phosphatase > 2.5 times ULN; AST and ALT > 2.5 times ULN.
             Creatinine > 1.5 mg/dL; Creatinine clearance < 60 mL/min]

          -  Patients with clinically significant hearing impairment

          -  Life expectancy less than 3 months

          -  Other malignancy within the past 3 years except basal cell skin cancer or pre-invasive
             carcinoma of the cervix.