Of note, although it has been suggested that epigenetic alterations of genes can occur as a consequence of, or coexist with, aberrant signaling of certain oncogenic pathways activated by genetic alterations, such as PIK3CA amplification, EGFR mutation and K-ras mutation [20,21], the interaction between genetic and epigenetic alterations in lung cancer still remains poorly understood. This evidence concerns the gene PIK3CA and lung cancer.