Real-time polymerase chain reaction (PCR) analysis showed that the right lower adenocarcinoma had an epidermal growth factor receptor (EGFR) mutation presenting as point mutation T790M in exon 20, while the left lower lung adenocarcinoma had a point mutation in exon 21 of EGFR (Fig. 3 a, b). Here, EGFR is linked to lung adenocarcinoma.