EGFR and lung adenocarcinoma: Significant differences in infection rates indicate that lung adenocarcinoma with EGFR gene mutations and lung adenocarcinoma without EGFR gene mutations have a different viral background, and that HCMV, EBV, and high-risk types 16 and 18 of HPV may therefore affect the etiology of EGFR-mutated lung adenocarcinoma.