The combined adjuvant clinical trials (E1199, E5188, and E3189) enrolled over 6000 women and found that women with obesity and HR-positive, HER2-negative breast cancer have worse disease-free survival (DFS) (HR = 1.24, 95% CI 1.06–1.46, p = 0.0008) and OS outcomes (HR = 1.37, 95% CI 1.13–1.67, p = 0.002) compared to women with normal weight [30]. This evidence concerns the gene ERBB2 and Obesity.