The present invention relates to a method for the prognosis of bone metastasis in HER2+ breast cancer, which comprises determining if the MAF gene is amplified in a primary tumor sample. Likewise, the present 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 MAF gene expression level, amplification or translocation. The present invention also relates to a method for predicting early bone metastasis in a subject suffering breast cancer. The present invention also relates to a c-Maf inhibitor as therapeutic agent for use in the treatment of HER2+ breast cancer metastasis. The present invention relates to kits for predicting bone metastasis and predicting the clinical outcome of a subject suffering from bone metastasis. Finally, the present invention relates to a method for typing of a subject suffering breast cancer and for classifying a subject from breast cancer into a cohort.
