The present invention is directed to methods and methods for the treatment, inhibition and/or reduction, and detection of metastatic tumors. In some embodiments, the inventive methods include systemic (e.g., intravenous) administration of a chlorotoxin agent that may or may not be labeled. In some embodiments, the inventive methods allow treatment, inhibition and/or reduction, and detection of metastases in the brain. In some embodiments, neovascularization is inhibited and/or newly formed vessels are caused to regress.