Methods, compositions and kits are provided for effectively treating and preventing cancer metastasis in vivo and for increasing survival of subjects burdened with metastatic tumors by targeting a lysyl oxidase or its modulator, especially human lysyl oxidase. Also provided are methods for identifying lysyl oxidase inhibitors and the use of such inhibitors to prevent and treat tumors, particularly metastatic tumors, alone and in combination with chemotherapeutic agents. Further disclosed is the use of lysyl oxidase levels for measuring metastatic potential and survival.