I can’t tell you the number of times a patient has been incredulous when they hear, that we can’t determine whether or not they have thyroid cancer. It should be simple and straightforward. After all biopsies of other body parts, for instance a breast biopsy, establishes whether or not a patient has breast cancer. Unfortunately diagnosing a thyroid nodule as benign or malignant is hardly straight forward.
The good news is that thyroid nodules are very common and most of them are fortunately, benign. Finding out whether a nodule is malignant or benign often starts with a trip to the endocrinologist or thyroid surgeon. An ultrasound is usually performed and then a small needle is used to retrieve cells from three or four different regions of the nodule. This procedure is called FNA or fine needle aspiration biopsy. Sometimes minimally invasive biopsies of thyroid nodules are inconclusive in determining whether the cells are benign or malignant. The pathologist is simply not able to definitively make a determination and an “indeterminate biopsy” often leads to extreme anxiety for patients.
There are a number of molecular tests that can help avoid thyroid surgery, in patients, by categorizing them as having a very low risk of thyroid cancer. The moloecular tests, like Afirma Gene Expression Classifier, are very helpful in identifying patients that do not have malignant thyroid nodules. If those molecular tests are negative, then the likelihood of having cancer, is less than 8% . If the Afirma Gene Expression Classifier results are positive, it means that likelihood of thyroid cancer is about 35-38% or more. Still the majority of patients with a positive Afirma Gene Expression Classifier test will not have cancer. The Afirma Gene Expression Classifier results help thyroid surgeons select the patient for whom surgery is appropriate and help us avoid operating on patients who are not likely to have thyroid cancer.
Advances in using molecular genetics and genomic science, are new tools tools to help guide patients with indeterminate thyroid nodules. Tests like the Afirma Gene Expression Classifier are designed to improve the diagnostic certainty of thyroid cytology. These new tools are not perfect, and they do not provide a clear answer. At SGLA, our thyroid surgeon, Dr Jason Cohen, is on the forefront in the advances of using molecular testing for the indeterminate thyroid nodule and will help his patients understand how to assess the results of gene expression based tests.
“An Update on the Status of Molecular Testing for the Indeterminate Thyroid Nodule and Risk Stratification of Differentiated Thyroid Cancer
by Nicholson, Kristina J.; Yip, Linwah
Division of Endocrine Surgery, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
Current Opinion in Oncology
Issue: Volume 30(1), January 2018, p 8–15