Inclusion Criteria:  ≥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; 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:  Pathological evaluation of the tissue sample has too few tumor cells (total number of tumor cells <100); K-drug mono-therapy is neoadjuvant therapy or adjuvant therapy; Other situations that the investigator thinks are not suitable for participating in this clinical study