Long-term outcomes of adjuvant mitotane therapy in patients with radically resected adrenocortical carcinoma

Abstract Context: In 2007, a retrospective case-control study provided evidence that adjuvant mitotane prolongs recurrence-free survival (RFS) in patients with radically resected adrenocortical carcinoma (ACC). Objective and Design: We aimed to confirm the prognostic role of adjuvant mitotane in the same series after 9 additional years of follow-up. Setting, Patients, and Interventions:One hundred sixty-two ACC patients who did not recur or die after a landmark period of 3 months were considered. Forty-seven patients were enrolled in four Italian centers where adjuvant mitotane was routinely recommended (mitotane group), 45 patients in four Italian centers where no adjuvant strategy was undertaken (control group 1), and 70 German patients left untreated after surgery (control group 2). Main Outcome Measures:The primary aim was RFS, the secondary was overall survival. Results:An increased risk of recurrence was found in both control cohorts [group 1: hazard ratio (HR) = 2.98; 95% confidence interval (CI), 1.75 to 5.09; P < 0.0001; group 2: HR = 2.61; 95% CI, 1.56 to 4.36; P < 0.0001] compared with the mitotane group. The risk of death was higher in control group 1 (HR = 2.03; 95% CI, 1.17 to 3.51; P = 0.011) but not in control group 2 (HR = 1.60; 95% CI, 0.94 to 2.74; P = 0.083), which had better prognostic factors and more aggressive treatment of recurrences than control group 1. The benefit of adjuvant mitotane on RFS was observed regardless of the hormone secretory status. Conclusions: Adjuvant mitotane is associated with prolonged RFS, without any apparent influence by the tumor secretory status. The retrospective nature of the study is a major limitation.