We could show that a negative brain metastasis tissue-specific TTF-1 status is associated with increased tumor cell proliferation on histopathological examination and tumor volume of brain metastases in pre-operative cMRI and that TTF-1 negativity was an independent marker for worse OS as well as intra- and extracranial PFS in LUAD brain metastasis. Here, TTF1 is linked to neoplasm.