TTF1 and adenocarcinoma: One subtype of NSCLC is the adenocarcinoma, which corresponds to about 40% of lung cancers.[2] Most cases of adenocarcinoma are associated with smoking; however it is also common in non-smokers and has become even more frequent in women than in men.[3] Primary lung adenocarcinoma are characterized by presence of thyroid transcription factor-1 (TTF-1).[4]