Amplification of FGFR1 has been reported in approximately 10% of breast cancer and may be associated with adverse outcome according to some reports. It has been reported to be associated with increased expression of FGFR1 and increased activity of downstream growth signaling pathways. Some reports suggest FGFR1 may have a role in regulating response to endocrine therapy. FGFR1 amplification may be a targetable alteration in some clinical settings (PubMed IDs: 20179196, 25400686).