Identifying Risk Factors for a High Lymph Node Ratio (over 0.8) in Papillary Thyroid Carcinoma Patients

Background Despite the majority of papillary thyroid carcinoma (PTC) patients has an excellent prognosis, central lymph node metastases (CLNM) are common. The relationship between CLNM and prognosis is still controversial, however, a certain lymph node ratio (LNR) has been reported to show significantly worse prognosis for PTC patients. Therefore, the extent of CLNM seems to play an important role in predicting the recurrence and survival of PTC. The aim of this study is to determine the risk factors for a high LNR (over 0.8) in central compartment in PTC patients. Methods A retrospective cohort study was conducted on PTC patients who underwent total thyroidectomy or lobectomy plus central lymph node dissection (CLND) between January 2011 and December 2015. Patients with an LNR over 0.8 was defined as Group A, and patients with an LNR 0 was defined as group B. The clinical and pathological factors such as gender, age, tumor size, tumor number, extracapsular spread (ECS), MACIS score, and co-existence of chronic lymphocytic thyroiditis （CLT）were compared between different LNR groups.Results Univariate analysis found high LNR to be associated with male gender, young age(<40 years) ,larger tumor (≥1 cm), ECS and absence of chronic lymphocytic thyroiditis. Multivariate logistic regression showed male gender (p = 0.007, OR = 3.79), young age(<40 years) (p = 0.000, OR = 0.159), larger tumor (≥1 cm) (p =0.033, OR = 2.530), and absence of chronic lymphocytic thyroiditis (p = 0.036, OR = 0.321) to be independent predictors for high LNR in PTC patients Conclusions Male gender, younger age (<40 years), larger tumor (≥1 cm) and absence of chronic lymphocytic thyroiditis were risk factors of high LNR. We recommend a prophylactic CLND should be considered in PTC patients with such risk factors.