CD8A and head and neck cancer: A forward program should establish a multi−scale atlas of the perineural neuro−immune niche in head and neck cancer, link spatial pathway activation to clinical endpoints, and deploy biomarker-selected trials that couple nerve-pathway–informed radiation with NGF/TrkA, chemokine-axis, and adenosine agents, while prospectively mapping function-evoked, branch-specific pain (e.g., trigeminal V1–V3 maneuvers, alloknesis/thermal algometry) and integrating these phenotypes with spatial immune readouts (CD8/Treg, adenosine metrics).