Based on the latest studies, recommendations for the best practical usage of IHC in lung cancer diagnosis considered Thyroid Transcription Factor 1 (TTF‐1) when it is detected by 8G7G3/1 monoclonal antibody and p40 as the best biomarkers for NSCLC subtypes but are not considered as diagnostic. This evidence concerns the gene NKX2-1 and non-small cell lung carcinoma.