Melatonin modulates the desmoplastic reaction in breast cancer, reducing the production of antiadipogenic cytokines in breast tumor cells, as well as their circulating levels, inhibiting the expression of aromatase and its respective promoters, and by stimulating the two main regulators of adipogenesis, C/EBPα and PPARγ, thereby supporting the differentiation of fibroblasts into adipocytes [48,51] (Figure 4). This evidence concerns the gene CYP19A1 and breast cancer.