Lymph node ratio is a prognostic predictor for patients with papillary thyroid carcinoma and lateral lymph node metastasis-the result of a retrospective cohort study at a single-center with long-term follow-up time

Abstract

Abstract Background Lymph node metastases (LNMs) are common in papillary thyroid carcinoma (PTC). The lymph node ratio (LNR) is suggested as a prognostic factor in many cancers. We aimed to evaluate the prognostic value of the LNR in PTC with lateral LNM. Methods This retrospective study reviewed the medical records of patients with PTC who underwent initial surgery in our institution from January 2000 to December 2012. The association of LNR and DSS was assessed using a Cox proportional hazards model with restricted cubic spline (RCS). Univariate and multivariate analyses were performed using Cox regression analysis to assess the factors predicting disease-specific survival (DSS). Results A total of 1036 patients with PTC were analyzed. After a median (range) follow-up of 90 (12–258) months, 45 patients died, 23 of whom died from thyroid cancer. The 10-year DSS for all study patients were 95.8%. Based on RCS curve analysis, a cutoff of 0.25 was selected for the LNR. A total of 587 (56.7%) patients had an LNR ≤ 0.25, and 449 (43.3%) patents had an LNR > 0.25. The 10-year DSS rates for patients with LNR ≤ 0.25 and > 0.25were 96.6% and 94.8%, respectively. Multivariate Cox regression analysis revealed that age group (HR, 9.13; 95% CI, 3.58–23.31, P < 0.001) and LNR (HR, 2.99; 95% CI, 1.22–7.33, P = 0.017) were independent predictors of DSS. Conclusion The results showed that an LNR greater than 0.25 was independently associated with an adverse DSS. LNR is a reliable predictor of both DSS of patients with PTC and lateral LNM.