In summary, our study reports that TrkA is a novel upstream activating kinase for STAT3, the TrkA and JAK2 pathways are concurrently activated in triple-negative and HER2-positive breast cancers, and the co-activation serves as a contributing factor to breast cancer stem cells and a new prognosis indicator for breast cancer metastasis to various organs. The gene discussed is STAT3; the disease is breast carcinoma.