Analysis of Gut Microbiota in Patients With Brain Metastasis of Non-small Cell Lung Cancer Treated by Pembrolizumab Combined With Chemotherapy

Inclusion Criteria: \- non-small cell lung cancer patients with less than brain metastases Patients must have received at least the first-line anti-tumor treatment, and the front-line treatment must include chemotherapy or targeted treatment with a platinum containing combination scheme, but not anti-PD-1 / L1 treatment Patients who have not received intracranial local treatment before Exclusion Criteria: \- Patients who toke major surgery within 4 weeks prior to enrollment or had ununited wounds Patients with hemorrhage in intracranial metastasis