In contrast, EGFR mutations (including exon 19 deletions and L858R substitutions) were found at comparable rates across tumor grades but showed a slight enrichment in Grades 1–2, consistent with the observation that EGFR-mutated adenocarcinomas often present with lepidic or acinar patterns typical of well to moderately differentiated tumors. The gene discussed is EGFR; the disease is adenocarcinoma.