Prognostic value of early postoperative calcitonin level in medullary thyroid carcinoma

Aims: Serum calcitonin (CT) assay is commonly used in the diagnosis and follow-up of medullary thyroid carcinoma (MTC). The aim of this study was to ascertain whether serum CT levels, measured in the first few days after surgery, could be used to evaluate the efficacy of treatment. Methods: A group of 33 patients was studied. In all patients the follow-up was more than 20 months. Results: Preoperatively basal CT serum levels were high in all patients. Twenty-four hours after surgery CT serum levels dropped to within the normal range in 8 patients and 72 hours after operation in 7 others. In this group 1 patient was at stage I, 11 at stage II and 3 at stage III. Basal and pentagastrin stimulated CT levels continued to be in the normal range in these 15 patients 6 and 12 months after surgery and at the subsequent year by follow-up visits. No clinical or radiological evidence of disease was found during the follow-up in this group. In the other 18 patients CT was reduced but still high 72 hours after surgery; 6 months later basal serum CT levels continued to be elevated or responsive to pentagastrin stimulation. In this group restaging showed tumor relapse in the thyroid bed in 2 patients, cervical lymphadenopathy in 11, and distant metastases (bone, liver) in 3. Conclusions: Immediate postoperative CT serum levels seem to be the most useful index to evaluate the efficacy of surgical treatment and the presence of residual neoplastic tissue.