Most previous studies have shown higher EGFR expression in squamous cell morphology compared to adenocarcinoma, (Hirsch et al., 2003; Nakamura et al., 2006; Rusch et al., 1997; Ludovini et al., 2013) although others have shown opposite results (Sun et al., 2015; Han et al., 2015). Here, EGFR is linked to adenocarcinoma.