The present invention relates generally to methods for identifying cancer patients with a poor prognosis, and to therapeutic modalities for improving prognosis by combating metastasis and abrogating chemoresistance in cancer cells. Embodiments of the present invention provide an objective means of prognostication regarding the long-term outcome of an incident of cancer, breast cancer in particular. Therapeutic modalities include immunotherapy and anti-sense therapy. Prognosis is determined by measuring the number of copies of the metadherin gene in the patient's cells.