Patients with breast cancer who had normal FGFR1 copy numbers showed lower expression rate measurements (IHC) for the estrogen receptor (median, 70%; IQR, 10% to 80%) than patients with FGFR1 amplification (median, 80%; IQR, 60% to 90%; Fig. 2a). This evidence concerns the gene FGFR1 and breast cancer.