Finally, Burugu et al. [41] studied LAG-3 expression in 4322 breast cancer specimens by immunohistochemistry and reported an improved outcome in patients with LAG-3 expression on TILs with a breast-cancer-specific survival (HR = 0.71, 95% CI: 0.56–0.90), particularly among estrogen receptor-negative patients (HR = 0.50, 95% CI: 0.36–0.69). Here, ESR1 is linked to breast cancer.