CD274 and non-small cell lung carcinoma: From 2014–2020, we retrospectively identified patients with non-small cell lung cancer brain metastases from the neuro-oncologic centers of the University Hospitals Cologne and Regensburg, Germany, who (i) had no previous local treatment, (ii) underwent preoperative contrast-enhanced MRI, (iii) had intrametastatic PD-L1 expression based on the immunohistochemical result of tissue samples after surgical brain metastasis resection.