ESR1 and breast cancer: Using ER+/PR+ tumors as the referent outcome in each subtype and poverty quartile Q1 as the referent covariable, we found that women with Luminal A breast cancer who live in counties with higher poverty were more likely to be diagnosed with ER−/PR+ disease (Q4: OR = 1.20, 95% CI = 1.03–1.40) (Table 3).