Calcitonin assessment in thyroid diseases is recommended when medullary thyroid cancer (MTC) is suspected in fine needle biopsy, as well as in suspicious for a follicular neoplasm class, especially oxyphilic type, in patients with germinal RET proto-oncogene mutation and in nondiagnostic biopsy when no surgical treatment is planned. This assessment is also suggested before any planned thyroid surgery to exclude MTC. Beyond diagnosis confirmation it is also suggested to take the concentration into account planning the extent of neck lymph node resection, although the threshold values are not precisely established. The aim of this work was to assess the prognostic impact of preoperative serum calcitonin concentration on primary surgery outcomes in medullary thyroid cancer. Among 1575 MTC patients followed-up in single clinical centre 248 patients were identified in whom serum calcitonin concentration before primary thyroid surgery was available (63 men and 185 women). Its mean concentration was 3647.8±18862.7 pg/ml (median 612 pg/ml, max. 286 643, min. 2 pg/ml). All patients underwent total thyroidectomy, and in 233 at least central and unilateral neck lymph node resection. In postoperative assessment in 145 patients serum calcitonin was undetectable and in 187 remained within normal ranges for healthy population (<10 pg/ml; in 11 of them in the follow-up calcitonin increased). In 217 patients after surgery no macroscopic cancer foci were visible in the imaging, and in further follow-up in 11 metastases or recurrence were found. Maximal preoperative concentration in patients who had no nodal metastases and normal calcitonin after surgery was 2513.8 pg/ml. Maximal preoperative concentration in patients in whom postoperative calcitonin was normal and were free from relapse in further follow-up was 15302.0 pg/ml. The minimal preoperative calcitonin in patients with histologiacally confirmed neck nodal metastases was 23 pg/ml. Conclusions: High preoperative serum calcitonin concentration up to a value of almost 12 000 pg/ml does not exclude the possibility of radical surgical treatment in MTC patients. Neck nodal MTC metastases can be found when serum calcitonin is as low as 23 pg/ml.
20 - 23 May 2017
European Society of Endocrinology