CTSF and brain neoplasm: Furthermore, in brain metastasis tissues from non-small cell lung cancer (NSCLC), CTSF expression is significantly higher compared to non-brain metastasis NSCLC and other primary brain tumors, with high consistency in CTSF expression between primary lung tumors and corresponding brain metastasis lesions, indicating that serum CTSF could serve as a specific biomarker for NSCLC brain metastasis [20].