CYP19A1 and cancer: The positive regulation of the CYP19A1 gene in the peritumoral tissues of women with a family history of cancer (10) may be justified by the accumulation of different genotypes for different mutations of the CYP19A1 gene that could affect the levels of gene expression, altering the activity of the aromatase enzyme, and consequently affecting levels of endogenous estrogen (47,10).