The present invention is in the fields of cell biology, immunology and oncology. The invention provides humanized antibodies that recognize αvβ6 integrins, which antibodies comprise a variable region of nonhuman origin and at least a portion of an immunoglobulin of human origin. The invention also provides methods for preparation of such antibodies, pharmaceutical compositions comprising them, and methods of treating, diagnosing and/or preventing various diseases and disorders by administering the humanized anti-αvβ6 antibodies of the invention. The invention also relates to the identification of differential expression of the integrin αvβ6 on the surfaces of tumor cells and tissues, the use of this differential expression in determining the metastatic potential of tumor cells, and methods of diagnosis and treatment/prevention of tumor metastasis and for elimination of residual metastatic tumor cells using ligands, particularly antibodies, that bind to integrin αvβ6.