Objective methods for detecting and diagnosing breast cancer (BRC) are described herein. Also described are methods of treating and preventing breast cancer and breast cancer metastasis as well as methods of assessing the prognosis of a breast cancer subject and the efficacy of a breast cancer therapy. In one embodiment, the diagnostic method involves determining the expression level of ZNFN3A1, a gene whose expression is markedly elevated in breast cancers, that therefore can be used to discriminate between BRC cells and normal cells. The present invention further provides methods of screening for therapeutic agents useful in the treatment of BRC, methods of treating BRC and method for vaccinating a subject against BRC.