Can the early reduction of tumour markers predict outcome in surgically treated sporadic medullary thyroid carcinoma?

Background and aims Patients with sporadic medullary thyroid carcinoma (MTC) have a variable clinical course. Our aim was to analyse the reduction of tumour markers after thyroidectomy with meticulous dissection and relate it to clinical outcome. Materials and methods Twenty consecutive patients with palpable sporadic MTC underwent thyroidectomy with central and uni- or bilateral modified radical neck dissection; three were subjected to mediastinal dissection. Basal (b-) and stimulated (s-) calcitonin (CT) and carcinoembryonic antigen (CEA)-levels were measured before and 6-8 weeks after primary surgery, and the reduction of these tumour markers was determined. Results Median CT (b- and s-) were markedly reduced after surgery (98.5% and 99.1%, respectively), and CEA decreased 11 times. CT (b-) fell > 99% in seven patients after surgery; in these and four additional patients, CT (s-) showed a similar reduction. During follow-up (median 52.5 months), two patients (stages IV B and C) died of MTC; they had < 95% reduction of CT. Four patients (stage IV A) are alive with verified metastases. Eight patients (one stage III, seven stage IV A) are alive with hypercalcitoninemia. Five stages I-III patients and one stage IV A patient are disease-free. Conclusions Thyroidectomy and meticulous dissection caused a pronounced reduction of tumour markers. A postoperative reduction of CT (s-) >= 97% seems to be associated with less aggressive clinical course, while CEA had lower predictive value.