Medullary thyroid carcinoma - Clinical characteristics, treatment, prognostic factors, and a comparison of staging systems

BACKGROUND. The clinical courses of patients with medullary thyroid carcino ma (MTC) vary, and a number of prognostic factors have been studied, but th e significance of some of these factors remains controversial. METHODS. The study group consisted of 104 patients with MTC or C-celI hyper plasia managed at the hospitals of the University of California, San Franci sco, between January 1960 and December 1998. Patients were classified as ha ving sporadic MTC, familial non-multiple endocrine neoplasia (MEN) MTC, MEN 2A, or MEN 2B. The TNM, European Organization for Research and Treatment o f Cancer (EORTC), National Thyroid Cancer Treatment Cooperative Study (NTCT CS), and Surveillance, Epidemiology, and End Results (SEER) extent-of-disea se stages were determined for each patient. The predictive values of these staging or prognostic scoring systems were compared by calculating the prop ortion of variance explained (PVE) for each system. RESULTS. Fifty-six percent of the patients had sporadic MTC, 22% had famili al MTC, 15% had MEN 2A, and 7% had MEN 2B. The overall average age at diagn osis was 38 years, and patients with sporadic MTC presented at an older age (P < 0.05). Thirty-two percent of the patients with hereditary MTC were di agnosed by screening (genetic and/or biochemical). These patients had a low er incidence of cervical lymph node metastasis (P < 0.05) and 94.7% were cu red at last follow-up (P < 0.0001) compared with patients not screened. Pat ients with sporadic MTC who had systemic symptoms (diarrhea, bone pain, or flushing) had widely metastatic MTC and 33.3% of those patients died within 5 years. Overall, 49.4% of the patients were cured, 12.3% had recurrent MT C, and 38.3% had persistent MTC. The mean follow-up time was 8.6 years (med ian, 5.0 years) with 10.7% (n=11) and 13.5% (n=14) cause specific mortality at 5 and 10 years, respectively. Patients with persistent or recurrent MTC who died of MTC lived for an average of 3.6 years (ranging from 1 month to 23.7 years). Patients who had total or subtotal thyroidectomy were less li kely to have persistent or recurrent MTC (P < 0.05), and patients who had t otal thyroidectomy with cervical lymph node clearance required fewer reoper ations for persistent or recurrent MTC (P < 0.05) than patients who underwe nt lesser procedures. In univariate analysis, age, gender, clinical present ation, TNM stage, sporadic/hereditary MTC, distant metastasis, and extent o f thyroidectomy were significant prognostic factors. Only age and stage, ho wever, remained independent prognostic factors in multivariate analysis. Th e TNM, EORTC, NTCTCS, and SEER staging systems were all accurate predictors of survival, but the EORTC prognostic scoring system had the highest PVE i n this cohort CONCLUSIONS. screening for MTC and early treatment (total thyroidectomy wit h central neck lymph node clearance) had nearly a 100% cure rate. Patients with postoperative hypercalcitoninemia without clinical or radiologic evide nce of residual tumor after apparently curative surgery may enjoy long term survival but have occult MTC. Only patient age at presentation and TNM sta ge were independent predictors of survival. The EORTC criteria, which inclu ded the greatest number of significant prognostic factors in our cohort, ha d the highest predictive value. (C) 2000 American Cancer Society.