Identifying risk factors of lateral lymph node recurrence in clinically node-negative papillary thyroid cancer

There is still debate regarding the role of routine central lymph node (LN) dissection in treating clinically node-negative papillary thyroid cancer (PTC). The aim of this study was to investigate the risk factors for lateral recurrence after total thyroidectomy and prophylactic bilateral central LN dissection in clinically node-negative PTC patients.We retrospectively collected the medical records of 1406 PTC patients who underwent total thyroidectomy and prophylactic bilateral central LN dissection between January 2004 and December 2008. We used Cox- proportional hazards regression analyses to inspect the predictive factors for recurrence.During a median follow-up of 107 months (range, 13-164 months), 68 (4.8%) and 37 (2.6%) patients experienced recurrence in any lesion and in lateral neck LN, respectively. Male, main tumor size >1 cm, nodal factors (pathologic N1a, positive delphian LN, and LN ratio >0.15), lymphovascular invasion, and extrathyroidal extension (ETE) were significantly associated with lateral neck LN recurrence in univariate analysis. Multivariate analysis showed that male (hazard ratio [HR], 2.217; 95% confidence interval [CI], 1.057-4.647; P = .035), main tumor size >1 cm (HR, 2.257; 95% CI, 1.138-4.476; P = .020), pathologic N1a (HR, 5.957; 95% CI, 2.573-13.789; P < .002), minor ETE (vs no ETE; HR, 3.027; 95% CI, 1.315-6.966; P = .009), and gross ETE (vs no ETE; HR, 4.058; 95% CI, 1.685-9.774; P = .002) were independent predictors for lateral neck LN recurrence.Among patients with pathologic N1a, those with LN ratio of more than 0.55 had worse lateral neck LN recurrence-free survival. Lateral neck LN recurrence in clinically node-negative PTC patients is predicted by the factors of male, main tumor size >1 cm, ETE, and pathologic N1a.