The prognosis of NX stage in patients with pT1 papillary thyroid cancer who underwent lobectomy

Abstract

Lymph node (LN) metastasis is known to impact the prognosis of patients with well-differentiated thyroid cancer. Herein, we aimed to determine the effect of NX stage on the prognosis of patients with papillary thyroid cancer who underwent thyroid lobectomy. We initially selected 1257 patients who underwent thyroid cancer surgery from 2012 to 2015. Of the 1257 patients, we included 556 in the analysis, excluding patients diagnosed with other types of thyroid cancer, those who underwent total or completion thyroidectomy, and those diagnosed with LN metastasis prior to surgery. The median follow-up time was 61.8 months (range: 12.3–108.9 months). After dividing the patients into N0, N1, and NX stage groups, we performed univariate and multivariate analyses. The 5-year recurrence-free survival (RFS) was analyzed using R version 3.2.5. The mean patient age was 45.0 ± 10.9 years. Of the 556 patients, 336 patients (60.4%) were diagnosed with N0 stage, 134 (24.1%) were N1 stage, and 86 (15.5%) were NX stage. Univariate and multivariate analyses were performed to identify prognostic factors for RFS. Considering gender, age, tumor size, surgery types, extrathyroidal extension, multifocality, and recurrence, no statistically significant differences were noted between the 3 groups. The 5-year RFS rates were 98.8%, 95.5%, and 97.6% for N0, N1, and NX groups, respectively, without significant differences between the 3 groups ( P = .56). Considering the T1b stage, the 5-year RFS rates were 100%, 93.1%, and 93.7% in the N0, N1, and NX groups, respectively, with a statistically significant difference between the 3 groups ( P = .018). Accordingly, the NX status cannot be deemed a prognostic factor for RFS in patients with papillary thyroid cancer who underwent thyroid lobectomy. However, the benefit of prophylactic central-LN dissection should be considered in patients with well-differentiated thyroid cancer diagnosed with T1b stage.