Abstract: The present invention relates to a method for the prognosis of bone metastasis in triple negative (including basal-like) breast cancer or, alternatively, ER+ breast cancer (including luminal A and B) which comprises determining if the c-MAF gene is amplified in a primary tumor sample. Likewise, the invention also relates to a method for determining the tendency to develop bone metastasis with respect to metastasis in other organs, which comprise determining the c-MAF gene expression level, amplification or translocation. The invention also relates to a method for predicting early bone metastasis in a subject suffering breast cancer. The invention also relates to a c-MAF inhibitor as therapeutic agent for use in the treatment of triple negative (including basal-like) breast cancer metastasis or, alternatively, ER+ breast cancer (including luminal A and B) metastasis. The invention relates to kits for predicting bone metastasis and predicting the clinical outcome of a subject suffering from bone metastasis.