To identify the risk factors for predicting contralateral central lymph node metastasis (CCLNM) in unilateral cN0 papillary thyroid carcinoma (PTC).

A total of 4265 patients with PTC confirmed by pathology at Peking Union Medical College Hospital from January 2013 to December 2015 were retrospectively analyzed, of whom 265 with unilateral cN0 PTC who underwent bilateral resection and bilateral central area dissection were included in this study. All patients were examined by ultrasonography before operation. Pathological results were used as the gold standard to analyze the differences of relevant clinical data and ultrasonic measurement indexes between the contralateral and non-contralateral central lymph node metastasis groups. Variables with statistical significance in univariate analysis were included into multivariate logistic analysis to identify independent risk factors for CCLNM in unilateral cN0 PTC.

Among the 265 patients, 28.3% had CCLNM. In the univariate analysis, microcalcification (84.1% vs 53.2%, χ²=20.306, P<0.001), larger lesions (69.3% vs 51.6%, χ²=6.901, P=0.009), pathological capsule invasion (82.6% vs 61.5%, χ²=6.775, P=0.009), fewer lesions (43.1% vs 25.9%, χ²=7.197, P=0.007), and younger age (90.7% vs 78.9%, χ²=5.062, P=0.024) were associated with CCLNM in PTC patients. However, there were no significant differences in gender, component, internal echo, blood flow, or Hashimoto's thyroiditis (P>0.05). Multivariate logistic analysis showed that microcalcification (OR=3.768, P=0.003) and pathological capsule invasion (OR=2.673, P=0.042) were independent risk factors for CCLNM.

The CCLNM rate in cN0 unilateral PTC patients with microcalcification and pathological capsule invasion is higher than that of patients without. These findings may be useful for identifying patients at higher CCLNM risk, so as to reduce tumor recurrence and distant metastasis, and improve the survival rate and quality of life of patients.