Evaluated the correlation between the qualitative test results of Xiamen Aide PD-L1 antibody reagent (immunohistochemistry) and the efficacy of Keytruda single-agent therapy, and the research data is used to support the registration and marketing of the assessment reagent

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

Patients with non-small cell lung cancer who have previously received single-agent K therapy