Active surveillance in thyroid cancer: a paradigm shift requiring critical appraisal and caution.

The recent inclusion of active surveillance (AS) for selected patients with differentiated thyroid cancer (DTC) in the 2025 American Thyroid Association guidelines represents a potential paradigm shift in clinical management. While AS has gained acceptance in other oncologic settings, its application to DTC raises several unresolved conceptual and practical issues. In this Letter, we critically appraise the definition, indications, and monitoring strategies proposed for AS in DTC, highlighting limitations related to preoperative risk stratification, imaging accuracy, and follow-up standardization. Particular attention is given to the implications for nuclear medicine practice and multidisciplinary decision-making. We also compare the evidence supporting AS in DTC with that available for other malignancies, underscoring the current lack of robust prospective data. We argue that, until stronger evidence becomes available, AS in DTC should be applied with caution and within a well-defined multidisciplinary framework, ensuring transparent communication with patients regarding uncertainties and potential risks.