Treatment of Advanced Medullary Thyroid Carcinoma with a Combination of Cyclophosphamide, Vincristine, and Dacarbazine: a Single-Center Experience

Objective: Experience with chemotherapy in patients with medullary thyroid carcinomas (MTC) is limited. This retrospective study evaluated the outcome of a combination of cyclophosphamide, vincristine, and dacarbazine ('CVD-regimen'), which has previously been suggested for treatment of malignant pheochromocytomas. Methods: 9 patients (5 males; age 55.0 +/- 4.0 years) with MTC were enrolled. Prior to chemotherapy, progressive disease was established in all patients by use of WHO criteria. On day 1 of each cycle, patients started with cyclophosphamide 750 mg/m(2), vincristine 1.4 mg/m(2), and dacarbazine 600 mg/m(2); on day 2, patients received dacarbazine alone (600 mg/m(2)). Treatment cycles were repeated at 21-day intervals and 6 cycles were planned for each patient. The standard imaging procedure was computed tomography, and the primary end point was the objective tumor response rate. After chemotherapy, patients were followed up until progression. Results: 9 patients underwent a total of 57 cycles (mean 6.3 +/- 0.3 cycles). Treatment responses were: 0% complete response, 11% partial response, 56% stable disease, and 33% progressive disease. The median progression free survival was 13.6 months (range 5.8-24.2 months). The median change (baseline vs. end of treatment) of calcitonin was -19% (range -70% to +174%). Reversible myelosuppression and moderate gastrointestinal symptoms were the most common adverse events. Conclusion: Although objective tumor response rates were low, the CVD regimen allowed disease stabilization for a substantial period of time and had acceptable toxicity. After initial surgery, chemotherapy may therefore be considered as a medical treatment option.