However, our analyses of ER/PR/HER2-defined subtypes in premenopausal women showed some evidence that recent obesity affected ER/PR/HER2-defined subtypes differently, with no association for luminal-like subtype and potentially increased risks of TNBC and HER2-enriched subtypes (per 5 kg/m2 increase, luminal-like OR = 0.97, 95% CI = 0.88–1.07; TNBC OR = 1.14, 95% CI = 1.00–1.31; HER2-enriched OR = 1.19, 95% CI = 0.98–1.45; P for homogeneity of slope coefficients per 5 kg/m2 increase = 0.02). Here, ERBB2 is linked to obesity due to melanocortin 4 receptor deficiency.