Catching it early
The detection of malignant thyroid tumours has increased in the general population due to advancements in imaging technology, particularly the widespread use of thyroid ultrasound. As a result, there has been a corresponding rise in the number of surgical procedures. However, thyroid tumours are often detected at a very early stage, at a small dimension, and often show an indolent nature. Active surveillance (AS) is often recommended for patients with small papillary thyroid microcarcinomas to reduce the cost and risks related to surgery. Despite this, some patients are unwilling to undergo AS; this consequently carries a risk of disease progression and potentially more invasive surgery. For these reasons, minimally invasive treatments (MIT) have become more widely used in patients with thyroid malignancies.
Why IR is the modality of choice
Minimally invasive treatments are mainly proposed as alternatives to thyroidectomy for incidental PTMC, with excellent results comparable to surgery, along with fewer complications, shorter hospital stays, and lower costs.
Surgery and radioiodine are the established treatments in cases of local relapse of thyroid cancer or the development of nodal metastases in the neck. However, repeated surgery carries a significant risk of complications and negatively affects patients’ quality of life, while radioiodine ablation is not always feasible and effective. As such, AS and MIT have been proposed as alternative options in cases of tumour relapse.
Minimally invasive treatments may be considered potential options for patients with unresectable thyroid carcinoma, such as medullary or anaplastic carcinomas, for the palliative purpose of tumour volume reduction and control of threatening local symptoms. These treatments have also been successfully applied to some patients with distant metastases from thyroid cancer, including liver, lung and bone metastases.
Expert advice
The European Thyroid Association (ETA) and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) released the “Clinical Practice Guideline for the Use of Minimally Invasive Treatments in Malignant Thyroid Lesions” in 2021, the first European guidelines on this topic. Based on a systematic PubMed search, an evidence-based approach was applied, and both the knowledge and practical experience of the panellists were incorporated to develop the manuscript and the specific recommendations.
In this document, it is recommended that when weighing between surgery, radioiodine, AS, or MIT for differentiated thyroid carcinoma, a multidisciplinary team, including members with expertise in interventional radiology, assess the demographic, clinical, histological, and imaging characteristics for appropriate selection of patients eligible for MIT. MIT should be considered particularly in low-risk PTMC patients who have a high surgical risk, short life expectancy, or relevant comorbidities, as well as those for patients who are unwilling to undergo surgery or AS. As laser ablation, radiofrequency ablation, and microwave ablation are similarly safe and effective, the choice should be based on the specific competencies and resources of the centres.
MIT can be considered as an alternative to surgical neck dissection in patients with radioiodine refractory cervical recurrences who are at surgical risk or decline further surgery. Factors that favour MIT include a previous neck dissection, the presence of surgical complications, small-sized metastases, and limited latero-cervical lymph node involvement.
When dealing with patients with unresectable oligometastatic or oligoprogressive distant metastases from thyroid tumours, it is recommended to consider thermal ablation among treatment options to achieve local tumour control or pain palliation. Additionally, thermal ablation may be used in combination with bone consolidation and external beam radiation therapy as a treatment option for painful bone metastases that are not amenable to other established treatments.