Compared to patients with breast cancer who had higher TIL densities, those with lower densities more frequently had skin infiltration (p = 0.005), ER positivity (p < 0.001), PgR positivity (p < 0.001), HER2 negativity (p = 0.015), and lower Ki67 (p < 0.001). Here, ESR1 is linked to breast cancer.