Endocrine Abstracts

Effective treatments of malignant pheochromocytoma have not been established. Although 131-I-MIBG radiotherapy, chemotherapy with a combination of cyclophosphamide, vincristine and dacarbazine (CVD), and molecular target therapies have been used for unresectable tumors, those are usually palliative and rarely curative. However, excessive catecholamine impairs the activities of daily living by causing various symptoms (e.g. palpitation, paroxysmal hypertension and hypotension and severe constipation) and even more fatal arrhythmia and heart failure. Therefore, controlling chronic overproduction of catecholamine is one of the most important therapeutic targets to maintain hemodynamics stable and to improve performance status of the patients. Although molecular target therapies such as tyrosine kinase inhibitors and the mammalian target of rapamycin (mTOR) inhibitor are promising and under clinical trial in the EU and North America, CVD is the most representative therapy available in Japan and only a limited numbers of case series have been reported. In our 14 patients treated with CVD, no patients showed complete biochemical and tumor responses. However, partial biochemical and/or tumor response was achieved in five patients (35.7%). No significant biochemical or tumor response was seen in four patients (28.6%), while deterioration in biochemical and tumor responses was seen in five patients (35.7%). These effects were demonstrated 1–5 months after CVD (average: 3+2 months) and lasted for 12–60 months (average: 32+21 months). The patients with biochemical response were associated with an improvement in diabetes mellitus and hypertension and were free from various symptoms and cardiac complications associated with catecholamine excess. In addition, adverse effects associated with CVD were transient and mild. Our results suggest that CVD still could be a beneficial treatment in relieving excessive catecholamine and related complications as well as in reducing tumor volume although the effects are limited in its magnitude and duration.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.