Subgroup analysis based on menopausal status showed that the risk conferred by this polymorphism was essentially restricted to premenopausal women in whom the combination of CYP1B1 (Val/Leu) and CYP1B1 (Leu/Leu) genotypes was associated with over 2-fold increased risk of breast cancer (OR = 2.04, 95% CI 1.10–3.78). Here, CYP1B1 is linked to breast carcinoma.