[Chronology of medullary carcinoma of the thyroid]

In order to study the chronological progress of medullary carcinoma of the thyroid, clinical records and histological findings of 62 patients with the tumor were reviewed. Postoperative plasma calcitonin levels were examined in 54 patients. Among the patients with the disease of the hereditary type, those of 30 years of age younger with no lymph node involvement and a tumor weight less than 5 g were most likely to have normal plasma calcitonin levels postoperatively, provided total thyroidectomy were performed. The peak of age distribution of patients of the hereditary type without lymph node involvement was 15 years less than that of those with nodal involvement. In the sporadic type, there was no correlation between teh age and the nodal nodal involvement. Plasma calcitonin levels in the patients with residual tumor showed exponential increase according to the time course. The regression lines, log y = log a + bx (y: plasma calcitonin level, x: years after operation), were calculated in 23 patients followed 6 months or longer. The doubling time of the plasma calcitonin level (T2), given as 1/b log 2, correlated well with the tumor progression rate. T2 for patients of the hereditary type were 0.8 years or longer except for one. Four patients of the sporadic type with T2 of 0.1-0.3 year within 3 years after operation.