A Single-Nucleotide Polymorphism in the Aromatase Gene Is Associated with the Efficacy of the Aromatase Inhibitor Letrozole in Advanced Breast Carcinoma

In patients with hormone receptor-positive metastatic breast cancer treated with the aromatase inhibitor letrozole, the presence of a SNP in the 3' untranslated region of the CYP19 aromatase gene is associated with improved treatment efficacy. Testing for the CYP19 rs4646 SNP as a predictive tool for breast cancer patients on antiaromatase therapy deserves prospective evaluation.