A 2023 meta-analysis similarly found higher risk of triple-negative breast cancer with ever OC use.62 However, an earlier study pooling data from 9 prospective studies could not confirm any association between OC use and breast cancer intrinsic subtypes.16 Previous studies have also not shown differences in associations with OC use by ER subtypes,9,16 consistent with our findings. Here, ESR1 is linked to breast cancer.