In a cohort of stages I-II and operable stage III breast cancer patients, it has been estimated that hormone receptor-(HR-) positive premenopausal patients carrying the long allele of the CYP19 TTTA polymorphism have a significantly longer disease-free survival (DFS) and overall survival (OS) than those without the long allele [10]. The gene discussed is CYP19A1; the disease is breast cancer.