There have been increasing studies indicated that tamoxifen has anti-tumor therapeutic effect in both ERα-positive breast cancer and ERα-negative tumors e.g. glioma, melanoma, colon cancer and pancreatic carcinoma though growth inhibition, apoptosis and autophagy, suggesting that tamoxifen could be an anther choice for ERα-negative tumor treatment [8]. The gene discussed is ESR1; the disease is breast cancer.