Endocrine Abstracts

JOINT2629

Adrenocortical carcinoma (ACC) is an aggressive tumor. 5-year overall survival (OS) for advance disease is <15%. However, cases of long-term disease stabilization have been reported. Mitotane monotherapy is usually reserved for biologically less aggressive tumors. A partial response (PR) rate to mitotane monotherapy of 13-31% has been reported. Typically, responses are observed when mitotane plasma levels are >14 mg/l, but sometimes PR and complete responses have been reached with lower levels. Currently, we cannot precisely define the biological characteristics of the disease and accurately predict the prognosis. In particular, no clinical or pathological factor has been validated to predict the response to mitotane monotherapy. We describe the case of a 45-year-old patient had an abdominal CT scan revealing a left adrenal mass of 15x16 cm, encompassing the ipsilateral kidney. Forty days later, the lesion measured 20 cm and extended into the contralateral adrenal lodge with para-aortic lymphadenopathy, pulmonary embolism, and multiple bilateral pulmonary nodules compatible with an aggressive metastatic ACC. A PET-FDG scan confirmed increased uptake in the left adrenal glands (SUV 12). After only 4 months, after mitotane treatment, a 45% reduction of the primary tumor and regression of lung metastases was observed, despite plasmatic drug levels of 5 mg/l. Subsequently, a further reduction in the size of the pulmonary nodules and the left adrenal mass (8x6 cm; 60%) was observed making surgical resection of the primary tumor feasible. Histology confirmed the ACC diagnosis. Mitotane represents an extremely effective therapy, also for aggressive tumors and despite plasma levels <14 mg/l.