ESR1 and cancer: Consistent with this hypothesis, we observed that the number of nevi seemed to be associated only with the risk of ER-positive cancers (multivariable-adjusted HR, 1.09, 95% CI, 1.02–1.16 for ER+/PR+ tumors; 1.08, 95% CI, 0.94–1.24 for ER+/PR− tumors; and 0.99, 95% CI, 0.86–1.15 for ER−/PR− tumors, for every five additional nevi; Table 2).