Factors associated with early complete resolution after radiofrequency ablation for low-risk papillary thyroid microcarcinoma: a dual-center retrospective study.

Abstract

To identify predictors of early complete ablation zone resolution (within 1 year) after radiofrequency ablation (RFA) for low-risk papillary thyroid microcarcinoma (PTMC). A retrospective dual-center study enrolled 225 patients with low-risk PTMC (2017-2022). Ablation zone volume was tracked during follow-up, with the specific time of complete resolution modeled using exponential decay functions. Multivariable Cox regression and restricted cubic spline (RCS) analyses identified independent predictors of resolution. Cumulative complete resolution rates were 62.2% at 1 year and 98.7% at 2 years. Independent predictors of complete resolution within 1 year included normal thyroglobulin antibody (TgAb) levels (hazard ratio (HR): 2.64, 95% confidence Interval (CI): 1.38-5.07) and thyroid peroxidase antibody (TPOAb) levels (HR: 1.92, 95% CI: 1.34-2.75), nodule diameter ≤ 5 mm (HR: 1.53, 95% CI: 1.02-2.29), and absence of intratumoral vascularity (HR: 2.77, 95% CI: 1.83-4.21). Energy density showed an inverted U-shaped relationship with resolution probability within 1 year (p < 0.001 for non-linearity). RFA achieves favorable long-term efficacy for low-risk PTMC, and complete resolution within 1 year is predictable by normal TgAb/TPOAb, smaller nodule size, absence of intratumoral vascularity, and moderate energy density. These findings may provide valuable insights for refining RFA techniques and the development of personalized follow-up. Question Predicting early complete resolution of low-risk PTMC after RFA is critical to mitigate concerns about treatment outcomes and optimize follow-up. Findings Normal TgAb/TPOAb, smaller nodule size, absence of intratumoral vascularity, and moderate energy density independently predict early complete ablation zone resolution within 1 year after RFA. Clinical relevance Identifying predictors of early resolution enables optimized RFA energy delivery and pretreatment decision-making. This provides doctors and patients with evidence-based guidance to refine ablation strategies and personalize management plans.