Consistency of PD-L1 Detecting Method Between E1L3N and 22C3 Monoclonal Antibodies in NSCLC Patients

Inclusion Criteria: 1. ≥18，advanced non-small cell lung cancer confirmed by histopathology, and have received K-drug mono-therapy in the past, the return visit information is complete, with traceable information such as tumor imaging examinations before and after treatment, and the curative effect can be judged; 2. Able to provide FFPE samples with a storage life of 4 years: 6 slices of continuous slices with a thickness of 3-5μm Exclusion Criteria: 1. Pathological evaluation of the tissue sample has too few tumor cells (total number of tumor cells \<100); 2. K-drug mono-therapy is neoadjuvant therapy or adjuvant therapy; 3. Other situations that the investigator thinks are not suitable for participating in this clinical study