SMAD4 and adenocarcinoma: The differences between these include the following: enriched expression of some genes (eg PIK3CA, ADH7 and SPRR3) in the SCC keratin—high compared with the SCC keratin—low cluster, more frequent CNVs, including common EGFR amplification in SCCs, a high number of aberrations in tumour‐suppressor genes related to TGF‐β pathway in adenocarcinomas including SMAD4 and TGFBR2 deletions, and increased DNA methylation in adenocarcinomas.65