Thyroid nodules are a very common disease worldwide. In mainland adults, the prevalence of thyroid nodules (more than 0.5 cm in diameter) detected by ultrasound is as high as 20.43%.
Despite the high incidence of thyroid nodules, most benign nodules do not require immediate treatment and are only monitored with regular medical follow-up. Only a few nodules continue to grow and may cause symptoms of local compression, at which point surgery should be considered.
So, what are the "non-surgical interventions" for benign thyroid nodules?
The diagnosis of "benign nodules" in the Guidelines for the Diagnosis and Treatment of Thyroid Nodules and Differentiated Thyroid Cancer (Second Edition) (hereinafter referred to as the Chinese Guidelines) and the 2015 Guidelines for the Diagnosis and Treatment of Thyroid Nodules and Differentiated Thyroid Cancer of the American Thyroid Association (ATA) in China is based on fine needle aspiration (FNA) cytology.
1. Dynamic follow-up
During dynamic follow-up, these key indicators should be addressed:
(1) Clinical symptoms: Most patients with benign thyroid nodules usually lack conscious symptoms, and only a few patients may experience neck discomfort or pain, or due to the pressure of the nodules on the surrounding tissues, they may have a feeling or difficulty swallowing a foreign body, hoarseness, breathlessness and even dyspnea, etc., and the appearance and degree of these symptoms are closely related to the size and location of the nodules. Thus, for most patients with benign nodules, the presence or absence of associated symptoms is not the primary focus of follow-up.
(2) Thyroid ultrasound: In the follow-up of benign nodules, ultrasound is regarded as the preferred method because of its convenience, economy, and wide availability. Particular attention should be paid to whether the nodule has a clinically significant "enlargement or growth" at follow-up, which is defined as an increase in the volume of the nodule (V=π/6× longitudinal diameter ×transverse diameter ×cephalopod diameter) by more than 50% or at least 20% increase in at least 2 diameters (and an increase of more than 0.2 cm), or the presence of new signs of malignancy, such as solid or very hypoechoic (including the solid part of cystic solid nodules), aspect ratio greater than 1, irregular morphology, microcalcifications, and extracapsillic invasion. At the same time, abnormal ultrasound features of lymph nodes, such as microcalcifications, cystic changes, strong echogenicity, rounding of lymph nodes, and peripheral blood flow, should also be noted.
(3) Serum thyroid-stimulating hormone (TSH): Since higher TSH levels (even within the reference range) are associated with an increased risk of nodule malignancy and advanced cancer stage, TSH levels should be monitored in combination with other risk factors that may lead to thyroid dysfunction.
(4) Calcitonin: Due to the low incidence of medullary thyroid cancer, the current domestic and foreign guidelines have neither support nor opposition to whether to perform serum calcitonin testing.
What is the best follow-up frequency?
The Chinese guidelines suggest that the frequency of follow-up should be determined in combination with ultrasound characteristics and cytological results, and for nodules with ultrasound signs or size that do not meet the indications for FNA, it is recommended to follow up every 6~12 months; Ultrasound and cytology suggest low-risk nodules, and the follow-up interval can be appropriately extended; However, for nodules that are cytologically benign and highly suspicious on ultrasound, repeat FNA testing within 12 months is recommended.
2. Ablation treatment
Which benign thyroid nodules are recommended for ablation?
The Chinese guidelines clearly state that ablation treatment is an option for patients with benign thyroid nodules who are progressively enlarged, have compressive symptoms, affect their appearance or have excessive mental concerns that affect their normal life, and are unwilling to undergo surgery. The 2022 Chinese Consensus recommends that ablation therapy be used as an alternative treatment when radioactive iodine therapy, antithyroid drugs, and surgical treatment are contraindicated.
What is the choice of ablation method for benign thyroid nodules?
Based on efficacy and adverse effects, ETA recommends radiofrequency ablation and laser ablation as first-line treatments, and microwave ablation and high-energy focused ultrasound ablation as second-line treatments.
Knowledge development
It should be noted that the Chinese guidelines, the ATA consensus, and the latest clinical practice guidelines of ETA all emphasize that benign nodules must be confirmed by FNA cytology before ablation treatment.
For nodules with different risk stratifications, the above guidelines and consensus also stipulate the frequency requirements for FNA. Nodules classified as category 1~3 by the American Society of Radiology's Thyroid Imaging Reporting and Data System (ACR-TIRADS) or classified as category 2 by the European Thyroid Society's Guidelines for the Risk Stratification of Thyroid Nodules in Adults with Ultrasound Malignancy (EU-TIRADS) require at least one FNA cell pathological diagnosis as benign; On the other hand, ACR-TIRADS class 4 or EU-TIRADS class 3 and above nodules require two FNA cell pathological diagnoses to be benign before ablation can be performed.
3. TSH suppression therapy
The efficacy of TSH inhibition therapy with levothyroxine (L-T 4) to shrink or stabilize nodules is still controversial, studies have shown that TSH inhibition therapy is only effective in iodine-deficient areas, and non-iodine-deficient areas are uncertain, and TSH inhibition therapy for 6~18 months can only reduce the nodule volume by an average of 5%~15%, and nodules may regrow after discontinuation.
In view of the fact that the vast majority of the population in mainland China is in a state of adequate or even excessive iodine, Chinese guidelines do not recommend TSH suppression therapy for patients with benign thyroid nodules with normal thyroid function.
This article is summarized
Thyroid nodules are common endocrine diseases in clinical practice, and their treatment strategies should be comprehensively considered according to the nature of the nodules and the specific situation of the patient. Most benign nodules can be effectively managed with regular follow-up, active monitoring, and non-surgical methods such as precise ablation therapy. Ultrasonography is the preferred means of monitoring thyroid nodules due to its simplicity, cost-effectiveness, and wide accessibility. In addition, ablation therapy has a good safety profile and health benefits.
When formulating a non-surgical treatment plan for thyroid nodules, doctors need to carefully evaluate the potential benefits and risks of treatment, and strictly grasp the indications for treatment to avoid unnecessary medical intervention and waste of resources. Through scientific and rational treatment options, we can not only reduce the physical and financial burden of patients, but also improve the overall quality and efficiency of medical services.
Resources
胡晓东,吕朝晖.甲状腺结节的非手术治疗[J]. 中华内科杂志, 2024, 63(6): 544-549. DOI: 10.3760/cma.j.cn112138-20240311-00157.