ESR1 and hepatocellular carcinoma: In support of this finding, we observed that HCC samples from patients with higher serum levels of AFP (>300 ng/mL) were more frequently ERα (−) tumors than ERα (+) tumors in our data and were more frequently ESR1-L tumors than ESR1-H tumors in TCGA-LIHC data (p < 0.001, chi-square test; Fig. 3c).