For ER/PR+HER2+ breast cancer, prior biopsy (HR = 1.49, 95% CI 1.08–2.05), atypical hyperplasia (HR = 2.56 95% CI 1.25–4.85), and obesity (HR = 1.59, 95% CI 1.18–2.13) were associated with increased risk. This evidence concerns the gene ERBB2 and obesity due to melanocortin 4 receptor deficiency.