Prognostic Impact of Surgical Extent in N1a-Stage Differentiated Thyroid Cancer: SEER Matched Analysis

Objective: To compare the prognosis of patients with differentiated thyroid cancer (DTC) in N1a stage following partial versus total resection. Methods: This study included patients aged 15 to 79 years diagnosed with N1a stage DTC, as per the 6th edition of the American Joint Committee on Cancer (AJCC) staging system, from 2004 to 2015. Exclusion criteria were: unknown ethnicity, M1 stage (6th edition AJCC), UNK stage group, pathological types such as anaplastic or medullary carcinoma, and indeterminate surgical extent. Cases were matched at a 3:1 ratio (total to partial thyroidectomy) based on a standard deviation difference in age of ≤0.01, an age discrepancy of ≤3 years, and identical T and overall stages. Survival analysis was conducted using the Kaplan-Meier method, and survival curves were generated. The log-rank and Breslow tests compared outcomes between groups. Cox proportional hazards regression model assessed the independent predictive capacity of variables, with a significance threshold of P<0.05. Conclusion: In balanced matched cases, the type of surgical intervention in patients with DTC in N1a stage did not significantly influence disease-specific survival (DSS; P=0.072). However, a significant effect on overall survival (OS) was noted ( P <0.05).