Independent Risk Factors Predicting Central Lymph Node Metastasis in Papillary Thyroid Microcarcinoma

The incidence of papillary thyroid microcarcinoma (PTMC) has risen rapidly in recent years, and PTMC patients with central lymph node metastasis (CLNM) usually have poor prognosis. Independent risk factors predicting CLNM in PTMC have not been well understood. The aim of our study was to identify useful clinicopathological risk factors predicting CLNM in PTMC patients. This was a retrospective study of 917 patients with PTMC treated with surgery from January 2014 to December 2015 in our hospital. The relationship between clinicopathological factors and CLNM was analyzed to identify those factors predicting CLNM in PTMC. Univariate and multivariate logistic regression analyses were further performed. Of 917 PTMC patients, 344 (37.5%) were found to have CLNM confirmed by intraoperative frozen-section examination. Multivariate logistic regression analyses further found several independent factors predicting CLNM in PTMC patients, including male gender (OR=1.75, 95% CI 1.17-2.61; p=0.006), younger age (<45 years) (OR=1.69, 95%CI 1.20-2.38; p=0.002), positive CLNM on ultrasonography (OR=10.20, 95% CI 5.51-18.88; p<0.001), multifocality (OR=1.69, 95% CI 1.00-2.85; p=0.04), and larger tumor size (>5 mm) (OR=2.80, 95% CI 2.01-3.91; p<0.001). The findings of our study identified several useful and independent risk factors predicting CLNM in PTMC patients, such as male gender, younger age, multifocality, positive CLNM on ultrasonography, and larger tumor size. The CLNM is very common in PTMC patients, and routine prophylactic central neck dissection may be recommended in PTMC patients with those independent risk factors of CLNM.