For breast cancer subtypes (Fig. 2), obesity was associated with all-cause mortality among patients with ER+ , ER/PR+ and HER2−, and patients with HER2+ tumors, whereas there were weak associations for patients with ER– and no clear associations for triple-negative breast cancer (TNBC) patients (1.05 [0.88–1.26]). This evidence concerns the gene ESR1 and obesity due to melanocortin 4 receptor deficiency.