Prognostic value of microscopic lymph node involvement in patients with papillary thyroid cancer

Abstract

Context: The impact of microscopic nodal involvement on the risk of persistent/recurrent disease (PRD) remains controversial in patients with papillary thyroid carcinoma (PTC). Objective: The goal of the study was to assess the risk of PRD and the 4-year outcome in PTC patients according to their initial nodal status [pNx, pN0,pN1microscopic (cN0/pN1) orpN1macroscopic (cN1/pN1)]. Design: We conducted a retrospective cohort study. Patients: The study included 305 consecutive PTC patients referred for radioiodine ablation from 2006 to 2011. Main Outcome Measure: We evaluated the risk of structural PRD and the disease status at the last follow-up. At ablation, persistent disease was consistently assessed by using post-radioiodine ablation scintigraphy combining total body scan and neck and thorax single-photon computed tomography- computed tomography (SPECT-CT) acquisition. Results: Of 305 patients, 128 (42%) were pNx, 84 (28%) pN0, 44 (14%) pN1 microscopic, and 49 (16%) pN1 macroscopic. The 4-year cumulative risk of PRD was higher in pN1 macroscopic than in pN1 microscopic patients (49% vs 24%, P = .03), and higher in pN1 microscopic than in pN0 (12%, P = .01) or pNx patients (6%, P