Although the advantage of mitotane is similar to that obtained with aromatase inhibitors over tamoxifen in adjuvant therapy of breast cancer,28 one must consider that the toxicity of mitotane is considerably higher than that of aromatase inhibitors.1, 6 Moreover, the challenges of adjuvant mitotane include a cumbersome regimen that entails a high number of tablets per day, a narrow therapeutic index, the need of a complex supportive therapy including high replacement doses of hydrocortisone, and a long treatment duration.6 The gene discussed is CYP19A1; the disease is breast cancer.