Analysis of risk factors for cervical lymph node metastases in papillary thyroid microcarcinoma
Objective: To investigate the risk factors for cervical lymph node metastasis of papillary thyroid microcarcinoma (PTMC). Methods: The clinicopathologic data of 169 patients with PTMC treated in the Department of Thyroid Surgery of Affiliated Hospital of Guiyang Medical University from January 2014 to March 2016 were retrospectively analyzed. Results: All the 169 patients underwent prophylactic central neck dissection, of whom 54 cases (32.0%) had central lymph node metastases; univariate analysis showed that age greater than 45 years old, multiple lesions and extrathyroidal invasions were related to central cervical lymph node metastases and multivariate analysis identified that age, multiple lesions and extrathyroidal invasion were independent risk factors for central lymph nodes metastasis (all P<0.05). Thirty patients received central and lateral neck dissection and of them, 18 cases (10.7%) had lateral lymph node metastases (18/30); univariate analysis demonstrated that the maximal diameter of the tumor, extrathyroidal invasion, multiple lesions and central lymph node metastases were associated with lateral lymph node metastases, and multivariate analysis indicated that only extrathyroidal invasion was a dependent risk factor for lateral lymph node metastases (P<0.05); 11 of the 30 cases (6.5%) had both central and lateral lymph node metastases, and both univariate and multivariate analyses found that multiple lesions and extrathyroidal invasion were risk factors for concomitant central and lateral lymph node metastases (all P<0.05). The sensitivity and specificity of high frequency color Doppler ultrasonography for detection of central lymph nodes metastasis was 14.8% and 96.5%, for detection of lateral lymph nodes metastasis was 94.4% and 83.3%, respectively. Conclusion: Age greater than 45 years, multiple lesions and extrathyroidal invasion are risk factors for PTMC cervical lymph node metastasis. High frequency neck ultrasound examination can be used as a preoperative assessment approach of PTMC lymph node metastases.