Mitotane treatment for recurrent adrenocortical carcinoma following adrenalectomy

A dog was referred for investigation into polyuria and polydipsia. Investigations showed a right adrenal mass, adrenalectomy was performed, and histopathology reported a carcinoma with local invasion. Carboplatin was selected as an adjuvant chemotherapy. Initially, did not show signs of recurrence, but 9 months later the clinical signs recurred, and staging was consistent with recurrence of the carcinoma with local hepatic invasion. The mitotane ablative protocol was chosen. Our patient developed mineralocorticoid deficiency 60 days later, but never developed clinical signs of cortisol deficiency as it was started on prednisolone. Kintzer and Peterson reported that dogs with metastatic disease experienced poorer response to mitotane and shorter survival time. However, our patient responded very well, with no side effect and remission of all clinical signs. The patient is alive at time of writing this report, 10 months after starting mitotane and 22 months after diagnosis.