ESR1 and breast cancer: In our exploratory analysis of the association between conservation of HIF-1α expression—positive HIF-1α expression in primary and recurrent tumors—and late recurrence, we observed an OR = 4.32 (95% CI 0.92, 20) for the association between conservation of HIF-1α expression and late breast cancer recurrence compared with loss of HIF-1α expression in the recurrent tumor in the ER+/TAM+ group.