Diagnostic value of calcitonin for lateral cervical lymph node metastasis in medullary thyroid carcinoma: a systematic review and meta-analysis

Objective To evaluate the diagnostic performance of preoperative serum calcitonin (Ctn) in detecting lateral cervical lymph node metastasis (LLNM) in patients with medullary thyroid carcinoma (MTC), identify the optimal threshold, and provide evidence for individualized neck dissection strategies. Methods Relevant Chinese and English databases, including PubMed, Embase, Web of Science, the Cochrane Library, CNKI, WanFang, and VIP, were systematically searched. Eight studies meeting the inclusion criteria, comprising a total of 951 patients, were selected. The QUADAS-2 tool was employed to assess the risk of bias. Meta-analysis was conducted using R software, comparing preoperative Ctn levels between LLNM and non-LLNM groups, with subgroup analyses performed according to different cut-off values. Results Preoperative Ctn levels were significantly higher in the LLNM group compared to the non-LLNM group (SMD = 1.00, 95% CI: 0.50–1.49). At a cut-off value of ≥300 pg/mL, the pooled sensitivity was 0.90, specificity 0.62, and diagnostic odds ratio (DOR) 13.48. At a cut-off of 200 pg/mL, sensitivity was 0.83 and specificity 0.42. The differences in specificity and DOR between the two cut-off groups were statistically significant. The pooled area under the summary receiver operating characteristic (SROC) curve was 0.894. Conclusion Preoperative serum Ctn demonstrates excellent predictive performance for LLNM in MTC. A threshold of ≥300 pg/mL serves as an ideal cut-off, providing a reliable, non-invasive indicator to guide “risk-oriented” individualized neck dissection and supplementing the limitations of conventional imaging in detecting micro-metastases.