Abstract: Objective To investigate the risk factors of cervical lymph node metastasis of medullary thyroid carcinoma(MTC),and to investigate the value of serum calcitonin(Ctn) in predicting cervical lymph node metastasis. Methods The clinicopathological data of 47 patients with postoperative pathological diagnosis of MTC were retrospectively analyzed,and divided into two groups according to whether or not there were cervical lymph node metastasis.The risk factors of cervical lymph node metastasis were analyzed by univariate analysis and Logistic regression analysis.The sensitivity and specificity of Ctn value in predicting cervical lymph node metastasis were studied by ROC curve. Result Univariate analysis showed that the lateral cervical metastasis group had larger MTC diameter( P = 0.004 ),higher serum Ctn( P =0.000) and CEA( P =0.003),multiple lesions rate(55.56% vs 13.79%, P = 0.004)  and higher central lymph node metastasis rate(77.78% vs 37.93%, P =0.015).Regression analysis showed that increased serum Ctn( P =0.036) and central lymph node metastasis( P =0.017) were independent risk factors for lateral cervical metastasis.When the Ctn cut-off point was 300.9 ng/L),the sensitivity,specificity and area under ROC curve(AUC) for predicting lateral cervical lymph node metastasis were 94.4%,62.1% and 0.808 respectively.  Conclusion  Elevated serum Ctn and central lymph node metastasis are independent risk factors for cervical lymph node metastasis of MTC,and Ctn can be used as a sensitivity index for predicting cervical lymph node metastasis.

Key words: medullary thyroid carcinoma, calcitonin, lateral cervical lymph node metastasis, risk factors