Patients with obesity who were diagnosed with ductal breast cancer had increased risk of BCR (HRadj = 1.53 [95%CI 1.00–2.34]), while no association was observed among patients diagnosed with lobular breast cancer (HRadj = 0.72 [95%CI 0.31–1.68]). This evidence concerns the gene BCR and obesity due to melanocortin 4 receptor deficiency.