Somatostatin analogs in the treatment of medullary thyroid carcinoma

The medical therapy for advanced or metastatic medullary thyroid carcinoma has not been fully established. Somatostatin analogs have been used with variable success in the therapy of a few patients with medullary thyroid carcinoma. In the present study, we evaluated the effects of somatostatin analog therapy on calcitonin (ct) and carcinoembryonic antigen in patients with advanced medullary thyroid carcinoma. Five patients (2 men and 3 women, aged 35-57 yr) with post-operative recurrent medullary thyroid carcinoma received somatostatin analog therapy for 12 weeks. All had been previously treated with total thyroidectomy and lymphadenectomy. Four of them showed positive uptake in 111In-pentetreotide scanning. One patient was treated with sc octreotide (100 μg/8 h), 3 patients received im slow release lanreotide (30 mg/14 days), and a further one received im octreotide LAR (30 mg/28 days). Serum samples for ct and carcinoembryonic antigen were obtained at 0, 1, 2, 4, 8 and 12 weeks of therapy. Therapy was well-tolerated in general, with minimal side-effects. One patient died after the first month of therapy because of advanced disease. Another patient showed normalization of his ct and carcinoembryonic antigen concentrations at the second week of therapy, maintaining elevated values thereafter. No clinically relevant changes in serum concentrations of ct and carcinoembryonic antigen were observed in the rest of the patients. One patient with positive 111In-pentetreotide scan, showed no uptake after somatostatin analog therapy. No significant decrease in the size of metastases was evident in the remaining patients. In conclusion, therapy with different formulations of octreotide and lanreotide does not seem to modify serum concentrations of ct and carcinoembryonic antigen in patients with recurrent medullary thyroid carcinoma.