Inclusion Criteria:

- Histologically confirmed high risk, locally advanced HNSCC patients (TNM staging:
T-any N2/3 M0, bulky T3 or T4 N-any M0) who would normally be offered cisplatin-based
radical chemoradiotherapy

- Estimated life expectancy of at least 12 weeks

- WHO performance status of 0 or 1

- Aged ≥18 years of age

- Adequate major organ function

- Willing to use contraception for the duration of the trial treatment and for six
months after completion of treatment

- Able to give informed consent

- Willing and able to comply with the protocol for the duration of the study

Exclusion Criteria:

- Head & neck cancers of the following types:

- Nasopharyngeal and paranasal sinus tumours,

- Oral squamous cell carcinomas (tumours of the oral cavity),

- Human Papilloma Virus positive oropharyngeal tumours (tonsillar and tongue base
tumours)

- Confirmed distant metastatic disease

- Previous chemotherapy or radiotherapy for the treatment of HNSCC tumour

- Previous therapy with a PARP inhibitor

- Pre-existing gastrointestinal disorders that may interfere with the delivery or
absorption of olaparib

- Grade 3 or 4 peripheral neuropathy

- Significant hearing difficulties or tinnitus (deaf patients can be included)

- The current use of drugs which are known to inhibit or induce CYP3A4