When a thyroid nodule is considered suspicious -- meaning that it has characteristics that may suggest thyroid cancer -- the key evaluation is a fine needle aspiration (FNA) biopsy. The FNA biopsy helps determine whether the nodule is malignant (thyroid cancer) or benign.
One of the most frustrating challenges facing endocrinologists and thyroid patients is when an FNA on a suspicious nodule is found to be "inconclusive" or "indeterminate." In this case, the pathology assessment cannot rule out cancer, and the recommended follow-up is thyroidectomy -- a surgery to remove the thyroid. The thyroid gland is then thoroughly evaluated by a pathologist to conclusively diagnose or rule out thyroid cancer.
When thyroid cancer is found, the thyroidectomy is considered a necessary and appropriate step in treatment.
But when no thyroid cancer is discovered, the patient has needlessly lost a vital organ, and in the process, become hypothyroid for life. The health impact of an unnecessary thyroidectomy can be life-changing -- those patients become hypothyroid and face a lifetime of tests, treatment and monitoring, as well as the symptoms and conditions associated with hypothyroidism.
In addition to the health impact, these needless thyroid surgeries are costly, and a drain on the healthcare system. The cost of thyroid surgery typically runs $15,000 to $20,000, and when the gland is needlessly removed, there are additional lifelong costs for blood tests, hypothyroidism medications and physician monitoring.
How Many People are Affected?Let's look at the extent of the problem. First, it's estimated that approximately 450,000 suspicious thyroid nodules undergo FNA annually in the United States. Up to 30% of the nodules assessed by FNA are indeterminate/inconclusive, meaning that thyroidectomy is recommended to as many as 135,000 patients due to an inconclusive FNA.
The crucial issue is that only 20 to 30 percent of inconclusive nodules turn out to be malignant. That means that as many as 100,000 patients in the US each year could end up undergoing a needless thyroidectomy, due to inconclusive nodules that turn out to be benign.
A new test, called the Afirma Thyroid FNA Analysis, can help avoid the negative health effects and costs of these needless thyroidectomies. The test, developed by a company called Veracyte, can help patients and physicians avoid inconclusive results on thyroid nodules through a two-step process. The first step is cytopathology -- pathology assessment at the cellular level -- by Thyroid Cytopathology Partners (TCP), an independent laboratory partner of Veracyte. Indeterminate samples go through step two, a proprietary Gene Expression Classifier, which then classifies indeterminate nodules as either benign or suspicious.
According to Bonnie Anderson, Veracyte cofounder and Chief Executive Officer, "The goal of the Afirma Thyroid FNA Analysis is to give doctors better information that can help patients with thyroid nodules avoid inconclusive FNA results –- and the potential diagnostic odyssey and unnecessary surgery that can follow such results. We believe this will not only improve patient care, but will also provide cost savings to the healthcare system."
The Afirma Thyroid FNA Analysis ProcessCurrently, the Afirma process can be used to evaluate adult patients (21 or older) with nodules greater than or equal to 1 cm in size.
Before an FNA is scheduled or performed, a patient who wants to use the Afirma Thyroid FNA Analysis Process needs to identify a treating physician who is already familiar with the test's collection process, and has the proper supplies on hand that are needed to collect and ship the sample. The test is not yet widely available throughout the country.
The treating physician performs a single FNA, which usually involves 4 to 5 samples, also known as "passes." The FNA sample is then split, with two passes collected for initial cytopathology and two passes collected in the event the first assessment is inconclusive. The physicians use standard thyroid FNA technique -- no special training is necessary -- but do collect the samples using sample collection and transport supplies provided by Veracyte.
The treating physician sends the patient samples overnight to Thyroid Cytopathology Partners, and the samples are then evaluated. They make a cytopathology diagnosis, and if the nodule is clearly benign or malignant, the Afirma Thyroid FNA Analysis is complete. A patient report is prepared and sent to the treating physician, usually within five days.
If the cytopathology is indeterminate, then the samples go on to a second step -- the Gene Expression Classifier. This is a genomic test that measures gene expression patterns of the sample to make a diagnosis of either "benign" or "suspicious for malignancy." If the initial cytopathology results are indeterminate, and the Afirma Gene Expression Classifier is used, the report usually is sent within 14 days.
Richard Lanman, MD, Veracyte's Chief Medical Officer, explains what it means to measure gene expression patterns:
"This refers to the ability to determine if particular genes in a cell are expressed, or 'turned on,' and how they are expressed in relation to each other as an indicator of the nodule's behavior -– for example, whether the nodule is benign or potentially cancerous. To develop the Afirma Gene Expression Classifier, Veracyte evaluated hundreds of thyroid samples to identify 142 different genes that best distinguish benignity from malignancy. The test is then based upon powerful algorithms and sophisticated statistical approaches that determine if and to what degree these genes are activated in a given thyroid FNA sample."