ESR1 and breast cancer: RecurIndex, a risk assessment model including diverse clinicopathological characteristics and genes closely related to breast cancer, is developed based on the Chinese population and has been demonstrated to be capable of predicting the long-term distant recurrence-free interval (DRFI) and recurrence-free survival (RFS) in patients with primary operable breast cancer, especially those with N0, ER/PR-positive and HER2-negative patients (11, 12).