In breast cancer, we used Global Test methodology and found recurrence-free survival was significantly associated with the GIPC1 signature only within specific molecular subtypes of the disease: patients with luminal B ER+ tumors (high-grade ER+; P = 0.015), ERBB2+/ER+ disease (P = 4.3×10−4), and perhaps basal-like or triple-negative cancers (P = 0.0074). The gene discussed is ESR1; the disease is breast carcinoma.