For patients with overweight or obesity and ER+ tumors, regardless of HER2 status, we found a decrease in odds of pCR compared with patients with normal weight (overweight, ORadj=0.66 [95%CI = 0.46–0.94]; obesity, ORadj=0.70 [95%CI = 0.47–1.02]) (Supplementary Table 3). This evidence concerns the gene ERBB2 and obesity due to melanocortin 4 receptor deficiency.