Mitotane With or Without Cisplatin and Etoposide After Surgery in Treating Patients With Stage I-III Adrenocortical Cancer With High Risk of Recurrence

Inclusion Criteria: * Have a histologically confirmed diagnosis of ACC (Weiss score of \>= 3). (LinWeiss-Bisceglia system will be used for oncocytic ACC). * Have a high risk of relapse defined as: Stage I-III ACC (according to the European Network for the Study of Adrenal Tumors \[ENSAT\] classification) within 90 days of surgical resection of primary tumor with curative intent with either microscopically complete resection (R0, defined as no evidence of microscopic residual disease according to surgical reports, histopathology, and perioperative imaging), microscopically positive margins (R1), or undetermined margins (RX, based on surgical or pathological reports without unequivocal evidence of metastasis in the perioperative imaging). Each participating center will determine the pathological stages and resection margins AND Ki67 \> 10% (to be determined by an experienced pathologist in each participating center and preferably via quantitative imaging analysis). * Have perioperative imaging (computed tomography \[CT\] with contrast, magnetic resonance imaging \[MRI\] of the chest/abdomen/pelvis, or fluorodeoxyglucose positron emission tomography \[FDG-PET\] CT) without unequivocal evidence of disease within 8 weeks before randomization. Patients with indeterminate non-specific nodules (\< 1 cm for soft tissue lesions and \< 1.5 cm in the short dimension for lymph nodes) will be permitted to participate in this study. * Have an Eastern Cooperative Oncology Group (ECOG) perfo…