A recent meta-analysis involving a large number of BC patients demonstrated that metformin not only increased the complete/partial response rate in BC but also suppressed various BC biomarkers, including HOMA-IR, insulin, sex hormones, SHBG, Ki67, obesity, hs-CRP, caspase-3, p-Akt, blood glucose, and the lipid profile [220]. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.