KRAS and adenocarcinoma: The link between AAH and invasive adenocarcinoma is strong and compelling: 5–20% of lungs resected for primary adenocarcinomas also harbour AAH, and AAH harbours some of the same genetic and epigenetic alterations found in adenocarcinomas including KRAS mutations8, EGFR mutations9, 10, loss of heterozygosity at 9q and 16p (ref. 11), TP53 mutations12, and epigenetic alterations in the WNT pathway13.