EGFR and lung adenocarcinoma: Regarding EGFR mutation frequency, a study by Sacher et al. [44] comprising 2237 NSCLC patients found an increased likelihood of EGFR mutations in patients diagnosed with NSCLC at a younger age, while Tanaka et al. [45] reported a significantly lower frequency of EGFR mutations in 81 lung adenocarcinoma patients ≤ 40 years compared with 1665 lung adenocarcinoma patients > 40 years at initial diagnosis.