Use of somatostatin analog SMS 201-995 in medullary thyroid carcinoma.

We have studied seven subjects with medullary thyroid carcinoma. Each had elevated basal serum calcitonin (CT) levels following total thyroidectomy. After subcutaneous administration of 100 micrograms of SMS 201-995, blood samples were collected at 60-minute intervals for six hours. Two patients showed a marked decrease of CT levels (patient A: baseline 565 pg/mL, nadir 150 pg/mL; patient B: baseline 1,632 pg/mL, nadir 416 pg/mL). The other five patients showed no significant change in comparison with saline infusion. Two patients were treated with SMS 201-995 (300 micrograms/day) for 90 days. One of these patients responded to the acute SMS 201-995 test and had CT levels persistently 50% lower than pretreatment values during this 90-day period. The other patient, whose CT levels did not decrease during the acute test, had persistently high values during this 90-day period but had relief of watery diarrhea even after the therapeutic trial was discontinued.