Long term prognosis of medullary thyroid carcinoma in 39 patients

Thyroidectomy and radical cervical lymph node dissection have been suggested as primary and secondary operations aimed at achieving biochemical cure in cases of medullary thyroid carcinoma (MTC). The purpose of this study was to find out behaviour of MTC in long-term follow-up, and to estimate possible difference in biological virulence between sporadic MTC and MTC in MEN2A.

From 1967 through 1994, 39 patients with MTC, including 9 patients with hereditary disease, were operated on at the Second Department of Surgery, Helsinki University Central Hospital. Enlarged lymph nodes were dissected selectively. The main outcome measure was carcinoma-specific survival.

In sporadic MTC, ten-year carcinoma-specific survival was 57.9% (95% CI 39.1%-76.7%) and ten-year survival after reoperation due to lymphatic node recurrence was 51.4% (CI 18.7%-84.2%). The presence of distant metastases at diagnosis (p = 0.0001) and extrathyroidal growth of the primary tumor (p = 0.0008) were independent predictors of carcinoma-specific survival in the Cox model. The risk ratio of sporadic MTC to MTC in MEN2A was 5.40 (CI 0.67-43.2) after adjusting the survival time for the size of the primary tumor.

Distant metastases and the local extrathyroidal extent of the primary tumor have a significant effect on the prognosis of MTC, lymphatic node metastases and other clinical factors being less important. The biological virulence of sporadic MTC may be clinically significantly higher than that of MTC in MEN2A.