In this multicenter study, we evaluated SNPs of CYP2W1 and CYP2B6 as potential predictive markers of response to mitotane in a large cohort of patients treated with mitotane monotherapy as first pharmacological therapy either after radical resection (group A) or in not completely resectable, recurrent or advanced ACC (group B). Here, CYP2W1 is linked to adrenal cortex carcinoma.