In five fibroadenomas and 10 phyllodes tumors, of which five had stretches of HIF-1α-positive epithelium, the mean shortest distance between microvessels and the epithelial basal membrane was 50 ± 11 μm for fibroadenomas and was 83.3 ± 16 μm for phyllodes tumors (P = 0.005). Here, HIF1A is linked to Fibroadenoma.