Ultrasound for Active Surveillance of Low-Risk Thyroid Carcinoma

Considering the indolent nature and favorable prognosis of low-risk thyroid cancer, active surveillance (AS) has become an increasingly attractive therapeutic option that can serve as an alternative to immediate surgery.AS is generally recommended for tumors measuring 1 cm without aggressive cytologic subtypes or evidence of gross extrathyroidal extension (ETE), lymph node metastasis (LNM), or distant metastasis.Ultrasound (US) is the gold-standard imaging modality for patient selection and disease monitoring during AS.Careful selection of candidates based on their individual and tumor-specific characteristics, as well as US findings, is essential for the safe implementation of AS.During surveillance, regular US examinations are performed to detect any signs of tumor progression, including an increase in size, new US features suggestive of gross ETE, or LNM.Consequently, US-based assessments play a pivotal role in determining whether to continue AS or proceed to surgical intervention.Although numerous guidelines for the effective application of AS in low-risk thyroid cancer have been published worldwide, there is no clear consensus on the standardized protocol for performing US.This review summarizes the optimal US techniques, characteristic findings, examination intervals, and criteria for conversion to surgery in patients with low-risk thyroid cancer, thereby facilitating the standardized implementation of AS in real-world clinical practice.