TTF1 and lung adenocarcinoma: Several studies have shown that positive TTF-1 expression is associated with both good prognosis and poor prognosis in lung adenocarcinoma.16,25–29 In addition, TTF-1 amplification is linked with poor prognosis in lung adenocarcinoma,30,31 and several studies suggest a possible oncogenic role of TTF-1 in lung adenocarcinoma as well as other types of cancers.