Active Surveillance for Low-Risk Thyroid Cancers: A Review of Current Practice Guidelines

Abstract

The indolent nature and favorable outcomes associated with papillary thyroid microcarcinoma have prompted numerous prospective studies on active surveillance (AS) and its adoption as an alternative to immediate surgery in managing low-risk thyroid cancer. This article reviews the current status of AS, as outlined in various international practice guidelines. AS is typically recommended for tumors that measure 1 cm or less in diameter and do not exhibit aggressive subtypes on cytology, extrathyroidal extension, lymph node metastasis, or distant metastasis. To determine the most appropriate candidates for AS, factors such as tumor size, location, multiplicity, and ultrasound findings are considered, along with patient characteristics like medical condition, age, and family history. Moreover, shared decision-making, which includes patient-reported outcomes such as quality of life and cost-effectiveness, is essential. During AS, patients undergo regular ultrasound examinations to monitor for signs of disease progression, including tumor growth, extrathyroidal extension, or lymph node metastasis. In conclusion, while AS is a feasible and reliable approach for managing lowrisk thyroid cancer, it requires careful patient selection, effective communication for shared decision-making, standardized follow-up protocols, and a clear definition of disease progression.

Keywords: Active surveillance; Guideline; Papillary thyroid cancer; Practice guideline; Thyroid neoplasms; Watchful waiting.

Fig. 1.

Guidelines on active surveillance (AS) for thyroid cancer. The guidelines were written in English, other than the Korean Thyroid Association (KTA) guidelines, which were first written in Korean and then translated into English. MSKCC, Memorial Sloan Kettering Cancer Center; MAeSTro, Multicenter Prospective Cohort Study of Active Surveillance on Papillary Thyroid Microcarcinoma; KoMPASS, Korean Multicenter Prospective Cohort Study of Active Surveillance or Surgery; JATS, Japan Society of Thyroid Surgeons; JAES, Japanese Association of Endocrine Surgeons; ATA, American Thyroid Association; ESMO, European Society for Medical Oncology; ETA, European Thyroid Association; EORTC, European Organization for Research and Treatment of Cancer; SFE, French Society of Endocrinology; AFCE, French Association of Endocrine Surgery; SFNM, French Society of Nuclear Medicine; SBEM, Brazilian Society of Endocrinology and Metabolism; JTA, Japan Thyroid Association; JSTS, Japanese Society of Thyroid Surgeons; NA, not available; PTMC, papillary thyroid microcarcinoma; US, ultrasonography; PTC, papillary thyroid carcinoma; EU-TIRADS, European Union Thyroid Imaging Reporting and Data System; FNA, fine-needle aspiration.

Fig. 2.

Ideal or appropriate tumor location for active surveillance (AS). (A) Ideal tumor location. (B) While tumors on the dorsal side of thyroid are excluded from AS, tumors on the ventral side can be considered for AS even if they exhibit contact with (c) or bulging of (b) the thyroid capsule, or if there is suspected invasion (i) into the strap muscle. (C) While tumors contacting the trachea at an obtuse angle (o) are excluded from AS, tumors contacting the trachea at an acute or right angle (a, r) can be considered for AS. (D) Some guidelines recommend against AS for tumors located close to the trachea or the recurrent laryngeal nerve, and they suggest that AS is appropriate for tumors surrounded by more than 2 mm of normal thyroid parenchyma.