Our observation that OGG1 depletion/inhibition leads to enhanced radiosensitivity of HeLa and HNSCC cells to relatively high-LET protons suggests that 8-oxoguanine residues are a major component of CDD sites, along with directly induced SSBs, and that OGG1 appears essential for their repair. The gene discussed is OGG1; the disease is head and neck squamous cell carcinoma.