Metastasis to the brain is a clinical problem in patients with breast cancer (1-3). We mined published microarray data (4, 5) to compare primary and metastatic tumor transcriptomes for the discovery of genes associated with brain metastasis in humans with metastatic breast cancer. We found that fibroblast growth factor 12, encoded by FGF12, was among the genes whose expression was most different in the brain metastases of patients with metastatic breast cancer as compared to primary tumors of

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... e breast. FGF12 mRNA was present at increased quantities in brain metastatic tissues as compared to primary tumors of the breast. Importantly, expression of FGF12 in primary tumors was significantly correlated with patient recurrence-free survival. Modulation of FGF12 expression may be relevant to the biology by which tumor cells metastasize from the breast to the brain in humans with metastatic breast cancer.