Olaparib is currently being dose escalated in combination with radical (chemo-)radiotherapy regimens for non-small cell lung cancer (NSCLC), breast cancer and head and neck squamous cell carcinoma (HNSCC) in three parallel single institution phase 1 trials (Study protocols of three parallel phase 1 trials combining radical radiotherapy with the PARP inhibitor Olaparib). This evidence concerns the gene PARP1 and head and neck squamous cell carcinoma.