Immunohistochemical (IHC) analysis of 92 breast cancer patients in Egypt reported higher expression of NPY1R in breast cancer tissues compared with non-neoplastic tissues and a positive correlation between NPY1R protein expression and presence of metastasis (P<0.001), clinical stages (P<0.0003), and estrogen receptor expression (P=0.004)[61]. This evidence concerns the gene ESR1 and breast carcinoma.