Meal-related changes in plasma calcitonin levels in patients with medullary thyroid carcinoma

Meal-stimulated gastrin release and calcitonin secretion

In order to study the effects of a physiologic meal on calcitonin (CT) secretion we studied 6 normal male volunteers (aged 28-34 yr). Each subject was given, on two separate days, either a mixed meal or 200 ml of distilled water, in random order. Gastrin (G) was effectively stimulated by the meal (F = 8.82; p less than 0.001) and reached a peak (with an average 100% increase) 30 min after the end of the meal, slowly decreasing thereafter; no increase was seen after water ingestion. On the other hand, CT levels remained stable throughout the observation period on both occasions. Ionized and total calcium did not show significant variations either after the meal or after water ingestion. These findings suggest that G alone, at the concentrations usually reached after a physiologic meal, is unable to stimulate CT secretion, at least in the absence of calcium increases.

Relation of doubling time of plasma calcitonin levels to prognosis and recurrence of medullary thyroid carcinoma

Plasma calcitonin (CT) levels were measured serially in 54 patients surgically treated for medullary thyroid carcinoma. Patients with postoperative basal CT levels higher than 1 ng/ml measured within 1 month after surgery had a higher recurrence rate than those with lower CT levels (p less than 0.002). Patients with postoperative basal CT levels higher than 2 ng/ml had a lower survival rate than those with lower CT levels (p less than 0.01). However, preoperative basal CT levels had no significant correlation with life expectancy or recurrence during the present observation period. Serial measurements in 23 patients with elevated postoperative CT levels showed exponential increases in basal CT levels in 19 patients (p less than 0.05 in nine patients, 0.05 less than p less than 0.1 in four patients) and slight decreases in four (p less than 0.05 in one patient). Doubling time of CT levels calculated from the regression line in each patient showed the highest correlation with 3-year survival, recurrence within 5 years, and time interval between surgery and clinical recurrence of the tumor, allowing quantitative prediction of the prognosis.

The values of calcitonin and carcinoembryonic antigen in the treatment and management of nonfamilial medullary thyroid carcinoma

Thirty-one patients were studied to evaluate the prognostic value of both calcitonin (CT) and CEA levels determined after the initial treatment in medullary thyroid carcinoma (MTC). Twenty-seven patients were evaluated three to nine months after initial treatment and four others afterwards. The CT and CEA levels were significantly higher and the survival rate lower in the eight patients with residual clinical disease as compared to the 19 patients in complete clinical remission. In patients in complete clinical remission, 11 had elevated CT level after treatment, and all had initial lymph node involvement. Five of these 11 relapsed and one died. None of the eight patients with normal CT levels after treatment relapsed. CEA levels were always abnormally high when patients relapsed. Fourteen patients in complete remission with high CT levels were followed for more than four years. Six had normal CEA levels and no relapse was observed. Eight of the 14 had pathological CEA levels and six of eight relapsed: five of these six patients presented CEA elevation from six to 36 months before the clinical relapse. In two of these six patients, a venous catheterization sampling method demonstrated infra clinical local recurrence. In two patients with liver metastases, the time course changes of CT and CEA levels were different and CEA appeared to be a more sensitive tumor marker than CT. These data are consistent with previous data concerning the values and limits of CT level for the management of MTC. Furthermore, this study demonstrates the prognostic significance of CEA determination in MTC. CEA appears to be a sensitive selective tumor marker capable of defining a high-risk subgroup.