MKI67 and adrenal cortex carcinoma: Before the ADIUVO trial, limited evidence was available on adjuvant mitotane treatment, and the indications of available guidelines1, 9 on adjuvant mitotane treatment were based on a meta-analysis of six retrospective studies only including just 322 treated and 718 untreated patients.2, 21, 22, 23, 24, 25 In the ADIUVO trial, the observed reduction in the risk of adrenocortical carcinoma recurrence following complete resection of tumours with a Ki67 proliferation index of 10% or less in patients who received adjuvant mitotane did not reach significance (HR 0·74 [95% CI 0·30–1·85]).