Molecular Imaging of DNA Damage Response by [18F]-Olaparib PET

Inclusion Criteria: 1. Patients \>18y, with biopsy-proven HPV-negative HNSCC, or patients \>40y with HPV-positive HNSCC and high-risk features (i.e. \> 10 smoke packs/year AND ≥N2b) 2. Treatment with chemoradiotherapy using platinum-based chemotherapy is anticipated 3. Recent archival tumour tissue (\<8 weeks prior to inclusion) should be available with suffi-cient residual material for determination of tumour PARP1 levels 4. Presence of a tumour lesion ≥10 mm in diameter 5. ECOG performance status 0-2 6. Negative pregnancy test in women with childbearing potential 7. Life expectancy \>3 months 8. Signed written informed consent and able to comply with the protocol 9. For stage II only: re-biopsy should be deemed feasible by the investigators (assessed by head-and-neck surgeon) Exclusion Criteria: 1. Recent treatment with PARP inhibitors or other investigational therapies \<30 days. 2. Presence of significant co-morbidities that make participation in the study undesirable according to the treating physician.