However, in ER+ breast cancers, FOXP3+ TILs were strongly associated with improved survival in the HER2+/ER+ subgroup, particularly in those with co-existent CD8+ T-cell infiltrates (HR = 0.48, 95% CI = 0.23 to 0.98), for which the presence of high levels of FOXP3+ TILs was independent of standard clinical prognostic factors. This evidence concerns the gene ESR1 and breast cancer.