A method of treating cancer or metastasis is provided involving administering at least one oncostatin M (OSM) antagonist to a subject, wherein the subject has been diagnosed with cancer. Administration of an OSM antagonist such as a small molecule pharmaceutical is provided as well as an anti-OSM antibody, an anti-OSM aptamer, and an OSM mRNA antagonist. The OSM antagonists were found to inhibit or prevent tumor cell detachment, proliferation and metastasis in several cancer types.
