Lung cancer has been a major health issue worldwide, including Taiwan. According to the data published by the Department of Health, Executive Yuan, Taiwan, 2004, lung cancer is already the leading cause of cancer-related death in Taiwan. Non-small cell lung cancer (NSCLC) represents approximately 75-85% of all primary lung tumors. The strongest prognostic factor for survival is whether the tumor can be completely resected. Surgical resection may be performed for those patients without distant or extended lymph node metastasis. Because of the significant morbidity and mortality for surgical procedure of lung cancer, it is therefore very important to identify and exclude those patients who can’t benefit from surgical treatment. Conventional staging, using chest/brain X-ray computed tomography, abdominal echography and radionuclide bone scintigraphy, leads to futile thoracotomies in up to 50% of patients.