In the United States, there is an estimated 10% lifetime probability for developing a
thyroid nodule.
Up to 15% of these nodules will prove to be malignant. The incidence of thyroid cancer is
increasing and is the third leading cause of cancer in women; accordingly, identification
of a nodule
1 cm or larger in diameter often prompts a sophisticated diagnostic evaluation comprised
of sonographic pattern risk assessment combined with fine needle aspiration biopsy
(FNAB), which enables the assessment of cellular morphologic features that could not be
identified by means of clinical assessment or imaging. Ultrasound-guided FNAB has been
shown to accurately classify 62-85% of thyroid nodules as benign, thereby avoiding
diagnostic surgery. Yet, 20-30% of aspirations still yield indeterminate cytologic
findings: "atypia (or follicular lesion) of undetermined significance," "follicular
neoplasm or suspicious for follicular neoplasm," and "suspicious for malignancy with a
risk of malignancy ranging from 6-75%." Most patients with cytologically indeterminate
nodules are referred for diagnostic thyroid surgery, but the majority prove to have
benign disease. For these patients, thyroid surgery is unnecessary, yet it exposes them
to 2-10% risk of serious surgical complications, and most would require thyroid hormone
replacement therapy for life. Research in recent years has focused on the potential of
molecular diagnostic approaches that could capitalize on increasing knowledge of the
molecular etiology of thyroid nodules and the transcriptional and mutation landscape of
thyroid cancers to augment diagnostic accuracy of FNABs. Most molecular profiling tests
demonstrate a high sensitivity and negative predictive value that helps to decrease the
number of benign nodules undergoing unnecessary diagnostic surgery. However, these
classified benign nodules may continue to grow and ultimately may need to undergo surgery
due to compressive symptoms. Although thyroid surgery has always been the mainstay of
treatment for symptomatic nodular goiters, and is associated with excellent outcomes in
experienced hands, thyroid surgery carries a low risk of complications that include
recurrent or superior laryngeal nerve injury leading to voice changes,
hypoparathyroidism, hypothyroidism with need for thyroid hormone supplementation, and
unsightly scarring. Although many patients with thyroid cancers find these risks
acceptable, these risks are sometimes less acceptable to patients with benign disease. In
an era when the medical field is treating thyroid diseases less aggressively, there is a
pressing need to identify approaches to treat indolent malignant disease less invasively.
Introduced in the early 2000s, ultrasound-guided percutaneous ablation of thyroid lesions
has emerged as a potential alternative to surgery in patients with benign thyroid
nodules. Of the myriad ablation methods, the most commonly used technique is
radiofrequency ablation (RFA). An expanding body of evidence shows that radiofrequency
ablation and other percutaneous interventions are effective treatments for benign solid
thyroid nodules, toxic adenomas, and thyroid cysts resulting in overall volume reduction
ranges of 40-70% with durable resolution of compressive and hyperthyroid symptoms. In
addition, RFA has been used as an effective alternative treatment in the management of
locally recurrent thyroid cancers in patients who are not good surgical candidates.
Although these percutaneous techniques have been steadily.
gaining acceptance in Europe and Asia over the past 20 years, they have been slow to be
adopted in the US. There remains a dearth of data regarding clinical experience in the
United States and no randomized clinical trials have been performed evaluating RFA vs
active surveillance for micropapillary carcinomas.