TTF-1 is a highly valuable marker in the diagnosis of lung cancer, particularly non-small cell lung carcinomas (NSCLC). Its expression is often seen in adenocarcinomas of the lung, making it useful in distinguishing these from other types of lung cancer such as squamous cell carcinoma, which typically does not express TTF-1. The presence of TTF-1 can also help differentiate primary lung tumors from metastatic tumors originating from other organs.
