Medullary thyroid carcinoma: prognostic factors and treatment

Seventy-five patients with medullary thyroid carcinoma (MTC) have been treated at Institut Gustave-Roussy from 1932 to 1979. Of these, 13 patients had distant metastases and received palliative treatment, their median survival was 3 years. Sixty-two patients with MTC limited to the neck received curative treatment; 6 had exclusive external radiotherapy for inoperable disease and 56 were surgically treated: 23 by total thyroidectomy and 33 by partial thyroidectomy. After surgery 29 patients received external radiotherapy for cervical lymph node involvement (25/29) and/or incomplete surgical resection (12/27). The survival rate was 69% at 5 years and 48% at 10 years. It was lower in patients with distant metastases at presentation (p less than 10(-5)), with tumoral infiltration of the posterior tissue planes (p less than 0.025) and in patients in whom surgical excision had not been satisfactory (p less than 0.01). It was not correlated with cervical lymph node involvement probably because those patients with lymph node involvement had been irradiated. The 29 patients who received post-operative cervical radiotherapy had initially more extensive local disease (p less than 0.05) than the 27 patients treated by surgery alone, nevertheless their survival was slightly higher. No difference in survival rate was observed between patients treated by total thyroidectomy or partial thyroidectomy, among whom only 4 local recurrences occurred. Three of the 6 patients treated with external radiotherapy alone experienced long survival (4, 7 and 10 years) and a fourth is still in clinical remission 4 years after treatment. The effectiveness of chemotherapy in patients with metastases was poor, only one patient out of 6 had a partial remission following a treatment by adriamycin. In the familial form and multiple endocrine neoplasia type II, total thyroidectomy appears to be indicated. In the sporadic cases, partial thyroidectomy is usually sufficient. External radiotherapy is effective in MTC and seems to be able to eradicate small foci of residual tumor; it is indicated when surgical excision is impossible or incomplete.