 Malignant tumors of the lung, esophagus, thyroid, or other mediastinal structures often involve the trachea by direct tumor growth compression and or invasion. In addition, extrathoracic cancers metastasize to these lymph nodes as well. However, surgical resection and airway reconstruction are the gold-standard treatment for MAO, many patients with airway involvement are poor surgical candidates based on physiologic or oncologic criteria.There are three main types of malignant airway obstruction: endobronchial obstruction, extrinsic compression, and a mixed pattern. For endobronchial obstruction, ablative techniques that destroy tissue are indicated, including lasers, electrocautery, argon plasma coagulation APC, photodynamic therapy, microdebriders, and cryotherapy, but primary tracheal cancers are less common than other types of lung cancer. If the obstruction is exclusively or mainly due to compression from outside the airway wall, the only option consists of placement of a stent or endoprosthesis. However, follow-up data has demonstrated that postoperative restenosis of stenting occurs in 5-45 of cases as a result of neoplastic infiltration through the mesh into the lumen or tumor overgrowth above and below the mesh stents. Encouraged by the success of 125I esophageal and biliary stent in esophageal carcinoma , a tracheal stent loaded with 125I radioactive seeds was developed in investigatorsinstitute. After successful in vitro and in vivo evaluations of the delivery system, investigator will prospectively compare responses to treatment with this irradiation tracheal stent versus the conventional self-expandable stent in patients with MAO. 