Korean Thyroid Association Guidelines on the Management of Differentiated Thyroid Cancers, Part II: Follow-up Surveillance after Initial Treatment 2026.

In patients with differentiated thyroid cancer, initial recurrence-risk stratification based on clinical, histopathological, and perioperative findings remains central to management during the first 1-2 years after initial treatment. Ongoing risk stratification (ORS) complements this initial assessment by continuously integrating longitudinal clinical data and treatment response, thereby refining long-term prognostic assessment and supporting individualized risk-adapted management. Building on the 2024 Korean Thyroid Association (KTA) guidelines, the 2026 KTA guideline incorporates new evidence from large Korean multicenter cohorts and comprehensive systematic reviews. The updated recommendations reinforce the continued application of ORS and provide more specific guidance on risk-adapted thyroid-stimulating hormone (TSH) targets, surveillance strategies for recurrence detection, and long-term follow-up tailored to individual recurrence risk and treatment response. Consistent with the evolving paradigm toward risk-adapted and individualized management, this revision updates recommendations regarding target serum TSH levels, serum thyroglobulin thresholds for response assessment and long-term surveillance, and follow-up intervals based on both initial-risk category and the ORS response category. These evidence-based recommendations aim to minimize unnecessary treatment and excessive surveillance in the majority of patients who have an excellent prognosis after initial therapy while ensuring individualized long-term management for patients who require closer surveillance or additional therapeutic intervention.