Preoperative basal calcitonin and tumor stage correlate with postoperative calcitonin normalization in patients undergoing initial surgical management of medullary thyroid carcinoma

BackgroundThe optimal initial operative management of medullary thyroid cancer (MTC) and the use of biomarkers to guide the extent of operation remain controversial. We hypothesized that preoperative serum levels of calcitonin and carcinoembryonic antigen (CEA) correlate with extent of disease and postoperative levels reflect the extent of operation performed.MethodsWe assessed retrospectively clinical and pathologic factors among patients with MTC undergoing at least total thyroidectomy; these factors were correlated with biomarkers using regression analyses.ResultsData were obtained from 104 patients, 28% with hereditary MTC. Preoperative calcitonin correlated with tumor size (P < .001) and postoperative serum calcitonin levels (P = .01) after multivariable adjustment for lymph node positivity, extent of operation, and hereditary MTC. No patient with a preoperative calcitonin level of <53 pg/mL (n = 20) had lymph node metastases. TNM stage (P = .001) and preoperative calcitonin levels (P = .04), but not extent of operation, independently correlated with the failure to normalize postoperative calcitonin. Postoperative CEA correlated with positive margins (adjusted P = 04). Neither preoperative nor postoperative CEA was correlated with lymph node positivity or extent of surgery.ConclusionPreoperative serum calcitonin and TMN stage, but not extent of operation, were independent predictors of postoperative normalization of serum calcitonin levels. Future studies should evaluate preoperative serum calcitonin levels as a determinate of the extent of initial operation.