American Thyroid Cancer Guidelines
Professor Sidhu Comments
Professor Stan Sidhu comments on key American Thyroid Association guidance for differentiated thyroid cancer, with practical context for Australian patients.
This page summarizes key themes from the updated ATA differentiated thyroid cancer guidance together with Professor Sidhu's comments for patients seeking practical Australian context.
Guidelines
Differentiated thyroid cancer (DTC) is the most prevalent cancer of the thyroid and is among the most frequently diagnosed cancers. The ATA practice guidelines for DTC management in adult patients were initially published in 1996, with subsequent revisions based on advances in the field. The goal of the latest update is to provide clinicians, patients, researchers, and those involved in health policy with rigorous, comprehensive, and contemporary guidelines to assist in the management of adult patients with DTC, emphasising the patient journey beginning with a thyroid cancer diagnosis.
Professor Sidhu Comment
The American Thyroid Association (ATA) guidelines for the management of adult patients with differentiated thyroid cancer is written for practicing clinicians in the United States. The document is very comprehensive however, patients in Australia need to understand that there is a difference in practice patterns between services provided in the USA and services provided in Australia. In this review, Professor Sidhu comments on some of the key points of these guidelines, which patients have quoted to him in the past to guide their decision making.
Guidelines Aim and Target Audience
The ATA document is intended to inform clinical decision-making using the DATA framework for patients as they proceed through their individual journey with thyroid cancer, minimising potential harm from overtreatment in patients at low risk for disease-specific mortality and morbidity while more intensively monitoring and treating patients at higher risk, including those with aggressive forms of DTC. These guidelines should not be interpreted as a replacement for clinical judgment and should be used to complement informed, shared patient–clinician consideration of complex issues.
Professor Sidhu Comment
I agree with the ATA committee that these thyroid cancer guidelines serve as a guide only. They are not a prescriptive document to be followed verbatim for the management of patients with thyroid cancer. One of the key differences between the US health care system and the Australian health care system is that we have universal health care coverage and a patient may seek treatment from any doctor or surgeon that they choose, with the expertise that they feel, would best serve their clinical problem. In the USA as opposed to Australia, health care insurance coverage is limited by the package that you are provided with on employment and therefore you are bonded to treatment in a certain health care environment, whether the expertise for the treatment of your disease exists or not. Hence, you may have a surgeon operating on your thyroid cancer in the USA who performs 1-5 thyroid operations a year as opposed to the Australian healthcare system where you can choose a surgeon who performs more than 500 neck operations per year regardless of your insurance status or geography. To seek ultra-specialist care for your thyroid cancer in the USA can result in extra significant cost due to treatment outside of what your insurance provides.
Diagnosis of Thyroid Cancer
Thyroid sonography with survey of the cervical lymph nodes should be performed in all patients with known or suspected thyroid nodules. Diagnostic thyroid/neck ultrasound should be performed on all patients with a suspected thyroid nodule, nodular goitre, or radiographic abnormality suggesting a thyroid nodule incidentally detected on another imaging study (e.g.computed tomography [CT] or magnetic resonance imaging [MRI] or thyroidal uptake on FDG-PET scan). Thyroid US can answer the following questions: Is there truly a nodule that corresponds to an identified abnormality? How large is the nodule? What is the nodule's pattern of US imaging characteristics? Is suspicious cervical lymphadenopathy present? Is the nodule greater than 50% cystic? Is the nodule located posteriorly in the thyroid gland? These last two features might decrease the accuracy of FNA biopsy performed with palpation. FNA is the procedure of choice in the evaluation of thyroid nodules, when clinically indicated in nodules >1cm.
Professor Sidhu Comment
The commonly cited guideline that only thyroid nodules greater than 1 cm warrant biopsy is an oversimplification. In my clinical experience, strict adherence to this threshold has resulted in missed thyroid malignancies. I have diagnosed multiple thyroid cancers measuring less than 1 cm that demonstrated clinically significant features, including cervical lymph node metastases and multifocal disease, thereby increasing the risk of local recurrence and complicating management. The size-based guide may at least be in part, a cost-containment strategy rather than a purely biologically driven standard. As a patient, if you are worried about a nodule after appropriate review by a thyroid cancer specialist and the nodule is deemed highly suspicious for cancer, then an FNA is clearly indicated. The American College of Radiologists has introduced a staging system for thyroid nodules called the TIRADs system, which tends to highlight the highly suspicious nodules for cancer for primary care practitioners and other physicians. TIRADs 5 nodules are deemed high risk for malignancy and would warrant needle biopsy regardless of size of the nodule.
Fine Needle Biopsy results
Thyroid nodule FNA cytology should be reported using diagnostic groups outlined in the Bethesda System for Reporting Thyroid Cytopathology. For a nodule with an initial non-diagnostic cytology result, FNA should be repeated with US guidance and, if available, on-site cytological evaluation. Repeatedly non-diagnostic nodules without a high suspicion sonographic pattern require close observation or surgical excision for histopathologic diagnosis. If molecular testing is being considered,patients should be counselled regarding the potential benefits and limitations of testing and about the possible uncertainties in the therapeutic and long-term clinical implications of results.
Professor Sidhu Comment
When a needle biopsy of a thyroid nodule gives a benign pattern, the risk of missing a cancer is less than 3% to 4%. When the needle biopsy returns as a Bethesda V lesion or Bethesda VI lesion, then the probability of cancer is 85% for Bethesda V and almost 100% for a Bethesda VI lesion. Most of the controversy exists when a nodule returns an atypical pattern of unknown certain malignant potential, i.e. Bethesda III or a follicular neoplasm Bethesda IV. The risk of cancer in these nodules is estimated based on needle biopsy result of 20% to 35%. It is in these lesions that an expert in thyroid cancer should evaluate the patient as the decision to proceed to surgery or observe is based on clinical history, clinical examination, ultrasound characteristics and the descriptors in the cytology report provided by the histopathologist. Often, if the diagnosis is in doubt, a second read is very important. Further, molecular testing is available to Australian patients. However, this typically involves sending samples to the United States for gene expression or mutation analysis at a cost exceeding AUD $2,000. These tests help stratify lesions into higher- or lower-risk categories for malignancy but do not completely exclude the possibility of cancer. If the risk of the operation is less than 1% for complications and the risk of missing a cancer is more than 10%, then the equipoise for treatment favours surgery. Nevertheless, patient preference remains central, and if a fully informed patient clearly chooses to avoid surgery, this decision should be respected.
Initial Management of Differentiated Thyroid Cancer
Shared decision-making between patients and their treating clinicians is paramount in determining the goals of initial therapy for patients with DTC. The preference of the patient must be considered when recommending the following, as appropriate: 1.In patients selected for thyroid surgery, the initial goal is to resect the primary tumour, any disease that has extended beyond the thyroid, and clinically significant lymph node metastases. Completeness of surgical resection is an important determinant of outcome, as lymph nodes represent the most common site (74%) of neck disease persistence/recurrence, followed by the thyroid remnant (20%) and the trachea and adjacent muscle (6%). 2. Consider which of the available multimodal treatment options is appropriate, to (a) decrease the risk of disease persistence/recurrence and metastatic spread and (b) minimize treatment-related morbidity. In addition to initial surgery, postoperative RAI administration, serum TSH suppression, and other management strategies may be appropriate in selected patients. Does surgical experience influence complication rates for thyroidectomy? Due to lower complication rates and improved outcomes on average associated with high volume thyroid surgeons (>25–50 thyroidectomies/year), patients with thyroid cancer should be offered referral to a high-volume surgeon, particularly for tumours requiring more extensive surgery. Patients undergoing total thyroidectomy for cancer at the hands of high-volume surgeons, are reported to have significantly less thyroid remnant tissue after resection, resulting in a reduced radioiodine dose requirement for remnant ablation.
Professor Sidhu Comment
The ATA guidelines represent the first formal thyroid cancer guidelines to address surgical volume. Although the definition of high volume is admirable at 25 cases per year minimum, I would consider a high volume surgeon one who performs more than 100 thyroidectomies per annum. Patients with thyroid cancer who are considering surgery should ask their surgeon about their personal complication rates. Specifically, they should inquire about the risk of permanent recurrent laryngeal nerve injury and permanent hypoparathyroidism. It is important to distinguish between complication rates reported from high-volume specialist centers and those reflecting an individual surgeon’s own outcomes. Surgeons may sometimes quote published rates from high-volume centers that do not accurately represent their personal results. Furthermore, the ATA makes a very important point that one marker of surgical expertise is often overlooked, that is the rate of recurrence in the thyroidectomy bed. Recurrence occurs several years later and hence it is difficult to ascertain completeness of resection until many years have passed. There is now evidence in the literature that comprehensive thyroid surgery leads to a much lower rate of persistent and or recurrent thyroid cancer disease.
Are there patients in whom active surveillance and percutaneous ablation are appropriate management options?
Active surveillance may be offered as an appropriate management option for some patients with cT1aN0M0(<1cm) PTCs.Shared clinical decision-making between the patient and clinical team regarding risks and benefits of this approach is essential. FNA is not routinely recommended for thyroid nodules <1 cm with low-risk features. However, if thyroid cancer is diagnosed in a tumor < 1cm by FNA, active surveillance is an acceptable management option in selected patients. There are limited data on the role of active surveillance in cancers >1 cm, as most of the existing studies have focused on enrollment for tumor sizes >1 cm.
Professor Sidhu Comment
In Australia, most true specialist endocrine surgeons are trained in performing and interpreting neck ultrasound. This allows the surgeon to surveil the thyroid and determine if critical structures such as the trachea and recurrent laryngeal nerve would be threatened by growth from a thyroid cancer being surveilled. I have operated on a number of patients where active surveillance was offered by physician and /or surgeon, only to find impending invasion or actual invasion of critical structures in the neck. Further, US can underestimate cancer size, and the final pathological cancer is larger than measured on US.
Thermal Ablation
Radiofrequency (RFA), microwave (MWA), laser (LA), and ethanol ablation have been studied as primary treatment of low-risk papillary thyroid cancer in carefully selected patients. Selection criteria are similar to those employed for active surveillance. Patients who are uncomfortable with active surveillance or with surgery may prefer a percutaneous ultrasound-guided ablative treatment for their cancer. Compared with lobectomy, ablation has a lower likelihood of resultant hypothyroidism, but it affords less certainty of complete tumour eradication and does not permit histopathologic evaluation.
Professor Sidhu Comment
Radiofrequency ablation for small microcancers, less than 1 cm located in the middle of the thyroid gland has been practiced in Asia for over a decade. There are now a large number of series which report acceptable outcomes for patients who wish to avoid hemithyroidectomy and/or the use of a thyroid tablet, who have opted for radiofrequency ablation. In some Asian countries, cultural preferences—particularly among women—play an important role in decision-making. Avoidance of a visible neck scar is a significant consideration, leading some patients to choose thermal ablation of a papillary microcarcinoma rather than surgery. I have specifically undergone training in Asia to offer this option to patients for whom it is their preferred choice of treatment of a small microcancer and I am comfortable to offer it as a possible treatment option.
What is the optimal operative approach for DTC?
When resection is performed for patients with thyroid cancer <2 cm without gross extra-thyroidal extension(cT1) and without metastases (cN0M0), the initial surgical procedure should be a thyroid lobectomy unless there are bilateral cancers or other indications to remove the contralateral lobe. For patients with low risk, unilateral thyroid cancer >2 and <4 cm (cT2N0M0), thyroid lobectomy may be the preferred initial surgical treatment due to significantly lower risk and side effects. However, the patient and treatment team may adopt total thyroidectomy to enable RAI administration and/or enhance follow-up based on disease features, suspicious contralateral nodularity and/or patient preferences.
Professor Sidhu Comment
Previous ATA guidelines had recommended total thyroidectomy for all thyroid cancers greater than 1 cm. The pendulum has shifted to surgical conservatism, offering hemithyroidectomy for patients with cancers up to 4 cm. The decision to offer hemithyroidectomy versus total thyroidectomy is complex and involves patient factors, patient preference, appearance of the cancer on clinical examination and ultrasound, the presence or absence of involved central or lateral lymph nodes and the expertise of the surgeon. The current American guidelines seem tailored more to lower-volume surgeons, where complication rates tend to be higher. As such, the guidelines favour hemithyroidectomy to minimize risks, with the assumption that more complex salvage surgery would be handled by a high-volume, experienced thyroid surgeon. The guidelines are not written for high volume, high expertise thyroid surgeons with extremely low complication rates as surgery can be safely performed whether it is hemi or total thyroidectomy. Our published recurrent nerve injury rate for thyroid cancer is less than 0.5%, and published hypoparathyroidism rate for thyroid cancer, including central nerve dissection routinely, is less than 1.5%. Furthermore, high grade features requiring post op adjuvant radioactive iodine (that can only be administered following complete removal of the thyroid) are only discovered on the post op histology. These features include lymph node involvement, grade of the cancer, and most importantly, vascular invasion. Further in Australia with a high level of still existing iodine deficiency, a lot of patients have bilateral thyroid disease leading to the consideration for total thyroidectomy in the first operation.
When should prophylactic central-compartment lymph node resection be performed?
Prophylactic central-compartment lymph node dissection should not be performed for most small, noninvasive, clinically node-negative PTC (cT1-T2, cN0) and for most FTCs. Prophylactic central-compartment neck dissection may be considered in patients with PTC and clinically uninvolved lymph nodes (cN0) who have advanced primary tumours (T3 or T4) or for whom the information will be used to plan further steps in therapy, but this approach should be weighed against the risks as they evolve during thyroidectomy.
Professor Sidhu Comment
This recommendation from the ATA clearly is one that is directed at low volume high complication surgeons. We have been routinely performing prophylactic central node dissection at the University of Sydney Endocrine Surgery Unit for over 20 years with very low rates of recurrent nerve injury and hypoparathyroidism as stated previously. Importantly, the ATA guidelines for risk stratification for recurrence includes the central lymph node status and without performing central node dissection that status is not measured. The important information we gained from central node status informs decision making regarding post op radioactive iodine ablation and is relied upon by our Endocrinology colleagues to assess thyroid cancer recurrence risk.
Need Individual Advice?
Guidelines are helpful, but they do not replace a detailed review of your ultrasound, biopsy, staging, and operative options.