Early calcitonin levels in medullary thyroid carcinoma: Prognostic role in patients without distant metastases at diagnosis.

Introduction: Calcitonin is themost specificmarker for medullary thyroid carcinoma, thus, low detectable calcitonin values after surgery can conceal persistent disease. The present study aimed to explore the prognostic role of pre-operative and early calcitonin levels in patients without distant metastases at diagnosis. Methods: A retrospective cohort of patients suffering from medullary thyroid carcinoma was considered (N=55). The final disease status, i.e. complete response (undetectable calcitonin levels and negative radiological assessments) or persistent disease (detectable calcitonin levels and/or positive radiological assessments), was deduced fromthe last available follow-up. Pre-operative and early calcitonin levels (i.e. six months after surgery) have been correlated to several clinical and histological features, according to the final disease status. Results: Persistent disease patients showed higher pre-operative and early calcitonin values (p=0.028 and p<0.001, respectively), compared to complete response sub-cohort. Cox-regression models show that early detectable calcitonin increases up to 18-fold the risk of persistent disease, independently from tumour size and pre-operative calcitonin levels (p=0.006). Of note, when considering only patients who finally developed distant metastasis, ROC curve analysis shows that an early calcitonin level =16 pg/ml predicts the final disease status with a sensitivity of 89% and a specificity of 82% (AUC=0.911, CI95%: 0.819-1000, p<0.001). Conclusion: Calcitonin levels six months after surgery represents an easy and effective predictor of persistent disease for medullary thyroid carcinoma without distant metastasis at diagnosis. [ABSTRACT FROM AUTHOR]