A research study involving 327 ER+ breast cancer patients as shown that the Luminal B patients with PgR- tumors had a relatively higher pathological complete response rate than patients with PgR+ tumors (29.5% versus 4.7% pCR, P < 0.001), but in Luminal B patients with a residual tumor after neoadjuvant chemotherapy, PgR absence was independently correlated with poor relapse-free survival (P = 0.017) and overall survival (P = 0.013) [24]. Here, ESR1 is linked to breast cancer.