Does pretreatment elevated calcitonin level cause the poor prognosis in patients with medullary thyroid cancer?

Background: Medullary thyroid carcinoma (MTC) patients have poor survival, tumor/node/metastasis (TNM) stage and biochemical prognosis are the most important factors. We investigated the clinical significance of calcitonin (Ctn) to assess the biochemical prognosis of MTC.Methods: This retrospective observational study enrolled 77 MTC patients with complete information and primary surgery at the Department of Thyroid Surgery, China Japan Union Hospital of Jilin University between 2009 and 2020. Patient and MTC characteristics were recorded. All patients were divided into remission, stable, and progression according to biochemical prognosis. We analyzed the correlation between preoperative serum Ctn, TNM stage and biochemical prognosis.Results: Elevated preoperative serum Cm was positively correlated with TNM, stage. Patients with higher Ctn, multifocality, and bilateral tumors were associated with a higher TNM stage. Multivariate logistic regression analysis showed that preoperative serum Ctn level was an independent risk factor for TNM stage. Receiver operating characteristic (ROC) analysis found the best Ctn cut-off value for predicting TNM III was 45.88 pg/mL, which had a sensitivity of 87.2% and a specificity of 65.8%. The best Ctn cut-off value for predicting TNM IV was 167.00 pg/mL, with a sensitivity of 92.9% and a specificity of 77.6%. In univariate analysis, patients with higher preoperative serum Ctn, multifocality, bilateral tumors, and higher TNM stage were more likely to progress. The optimal cut-off value for progression was 195.5 pg/mL, which had a sensitivity of 80.0% and a specificity of 70.2%. For every 1-unit increase in preoperative serum Ctn levels, the risk of progression increased by 1.004 times (P=0.008), and patients with TNM stage III [hazard ratio (HR) =9.663; 95% confidence interval (CI): 1.411, 66.156] were nearly 9.7-fold more likely to progress than those in TNM stage I/II.Conclusions: Elevated preoperative serum Cm predicted poor clinical outcomes in MTC.