EGFR and head and neck squamous cell carcinoma: EGFR-positive tumor cells (Fig. 5C) were dense in HGG (3,000 ± 450 cells/mm2) and HNSCC (2,100 ± 180 cells/mm2) but sporadic in LAC (1,300 ± 100 cells/mm2), with fewer than 10 cells occupying over 50% of tumor areas (Supplemental Fig. 12).