Mass in left lower lung is not necessarily lung cancer, let alone advanced stage. First of all, the etiology of left lower lung mass is complicated, which may be benign tumor or lung cancer, but there is no way to be 100% sure that it is lung cancer from the mass. Secondly, the advanced stage of lung cancer needs to be determined according to TNM staging criteria, that is to say, it needs to look at the size of the tumor, lymphatic metastasis and metastasis to remote organs. A mass in the left lower lung is only a manifestation, and there is no way to know its size and metastasis, so there is no way to determine the patient’s staging, which may be in early stage or in advanced stage. In order to further understand the nature of the mass and clarify the clinical staging, it is necessary to improve the pathological tissue biopsy, enhanced CT, MRI, PET-CT and other examinations in time to further determine whether the lung cancer is in advanced stage or not.