[Evaluation of surgical results and prediction of prognosis by analysis of serum tumor marker levels: proposal of a theory tested on patients with medullary thyroid carcinoma].

A theory to evaluate the benefit of surgery and to predict the prognosis in patients with a malignant tumor by analysis of serum tumor marker levels is proposed, and an analysis of 67 patients with a medullary thyroid carcinoma is reported as an example of its application. This theory incorporates the following concepts: the tumor marker doubling time, the reduction index, the expected prolongation of survival by surgical therapy, and the expected duration of survival after surgery. These parameters allow a quantitative judgement of the surgical therapy and a quantitative prediction of the subsequent prognosis as demonstrated in patients with a medullary thyroid carcinoma.