Background. The aim of the study was to analyze the impact of combined treatment (thyroidectomy, external beam radiotherapy and radioactive iodine treatment) on the long-term survival of medullary thyroid carcinoma patients.
Methods. This is a retrospective study. In 1977–2006 59 patients (43 female, 16 male, median age 49 years, range 15–77 years) were treated for medullary carcinoma at the Institute of Oncology Vilnius University, of them 56 patients were classified as sporadic and 3 patients as familial cases. Thyroidectomy was performed for all patients; 22 patients with lymph node metastases underwent cervical lymph node dissection; 52 patients received postoperative conventional external beam radiotherapy (EBRT) at a median dose of 44 Gy (38–60 Gy), 33 patients additionally received radioactive iodine 131I (RAI) at a median dose of 4.6 GBq (2.6–13.8 GBq), 7 patients were treated only surgically. All 59 patients were treated with L-thyroxine; the dose was adjusted to keep the TSH in the normal range (0.17–4.05 μIU/ml). The survival was estimated by the Kaplan–Meier method. The statistical difference between the survival curves was determined using the log-rank test.
Results. The survival of MTC patients was 88.0% (95% CI 68.0–88.9), 67.9% (95% CI 52.3–79.4) and 60.5% (95% CI 43.2–74.0), respectively, 5, 10 and 15 years after diagnosis. In the survival analysis, only patients’ sex and lymph node involvement were found to be significant prognostic factors.
Conclusions. The results of the study suggest that treatment with radioiodine and external beam radiotherapy do not improve significantly the long-term survival of surgically treated MTC patients.

Keywords: medullary carcinoma, thyroidectomia, ¹³¹J, external beam radiotherapy