Afirma® Gene Expression Classifier (GEC)
The Affirma Gene Expression Classifier (GEC) is a modern molecular diagnostic test designed to improve the accuracy of thyroid nodule evaluation. When traditional biopsy results are unclear, this advanced test can help determine whether a thyroid nodule is likely to be benign, reducing the need for unnecessary surgery.
How the Test Works
The first step in evaluating a thyroid nodule is usually a neck ultrasound. This painless imaging test shows the size, shape, and internal features of the nodule and helps determine whether a biopsy is needed.
If further evaluation is recommended, the next step is a fine-needle aspiration (FNA) biopsy, which is almost always performed under ultrasound guidance. Using ultrasound ensures the needle is placed precisely into the nodule, even if it is small or located deep in the thyroid. This increases both accuracy and safety.
The collected cells are examined by a pathologist. If the results are indeterminate, not clearly benign or malignant, part of the biopsy sample can be sent for Afirma testing.
In the laboratory, Afirma analyzes the activity of hundreds of genes in those thyroid cells. Every nodule has a unique molecular “signature,” and the test uses this information to classify the nodule as:
Benign profile – patterns consistent with non-cancerous nodules. In many cases, surgery may be avoided.
Suspicious profile – features more often seen in cancerous nodules. Surgery or closer monitoring may be recommended.
For patients, the procedure feels no different from a standard thyroid biopsy. The only additional step is that the sample is sent to a specialized laboratory, with results typically available in a few weeks. Afirma is most useful for patients with indeterminate thyroid nodules, such as Bethesda categories III or IV (AUS/FLUS or follicular/Hürthle cell neoplasm).
Why It Matters
Thyroid nodules are common, and while most are benign, up to 30% of biopsy results can be indeterminate. In the past, patients with unclear results often underwent thyroid surgery just to obtain a diagnosis, even though most nodules turned out not to be cancer.
The Afirma GEC helps change this. By providing additional clarity, it:
Reduces unnecessary surgeries, allowing many patients to avoid thyroid removal and lifelong medication.
Gives peace of mind, offering greater certainty when biopsy results are unclear.
Supports personalized care, ensuring treatment decisions are based on the best available evidence.
Advances clinical practice, as studies show Afirma significantly decreases the rate of diagnostic surgery for indeterminate nodules.
By integrating ultrasound imaging, ultrasound-guided biopsy, and molecular testing, this approach ensures patients receive the most accurate diagnosis with the least invasive care possible.