Category: Thyroid

Monitor: 18

18 - OUTCOMES OF MOLECULAR TESTING IN CYTOLOGICALLY INDETERMINATE THYROID NODULES

Thursday, Apr 25
12:30 PM – 1:00 PM

Objective : A high proportion of thyroid nodules that undergo fine-needle aspiration are classified as cytologically indeterminate. Molecular testing offers a unique approach to improve risk stratification, allowing clinicians to assess indeterminate lesions, avoiding unnecessary surgical procedures. Currently, 4 tests are commercially available, with Thyramir ™/ThyGenX ™ being one of the cheapest options. We aim to determine the clinical accuaracy of this test by retrospectively reviewing documented results of our patient with their clinical outcome after surgery and/or post-testing sonographic and serologic surveillance.


Methods : Data from a total of 250 patients who were evaluated for thyroid nodules and had a fine needle aspiration biopsy between September 2015 and October 2018 at a large endocrinology practice in Houston, Texas were utilized in this study. Of these 250 patients, 218 (87.2%) had outright benign or malignant cytopathology results and were excluded. Samples from the 32 (12.8%) patients whose results were classified as “Indeterminate” were sent for further molecular testing with Thyramir ™/ThyGenX ™.


Results :

Of the 32 results that were classified as Indeterminate, mean age was 54.1 years (range: 21 years to 79 years); 25 (78%) had benign results. From this sample, 2 patients (6.3%) had a positive Thyramir™ panel while a total of 9 (28%) patients had positive genetic mutations on the ThyGenX™ panel. Of those, 4 had the NRAS mutation, 2 had HRAS, 2 had BRAF and 1 had the TERT mutation. Only 1 (3%) patient was positive for both tests. The totality of patients with positive results underwent surgical resection. Postsurgical pathology was compatible with the molecular analysis. At the time of this review, none of the patients who had a positive molecular result have evidence of malignancy postsurgery. Patients who had a negative result have clinically insignificant changes in the thyroid nodule by ultrasound.


Discussion :

Thyramir ™/ThyGenX ™ does not have reported post-validation studies, which is a considerable drawback compared to other tests available in the market. Estimation of the impact of the test must consider the number of surgeries being avoided, the number of misclassified cases with a malignancy and the overall cost of the molecular test (counting with the prior biopsy and cytopathological analysis).


Conclusion : Among the subset of thyroid nodules cytologically classified as atypia of undetermined significance/follicular lesion of undetermined significance or follicular neoplasm/suspicious for follicular neoplasm, the majority will have no molecular evidence of malignancy.

Leonardo Pozo Garcia

Resident
University of Texas RGV-DHR
McAllen, Texas

Leonardo is a first year Internal Medicine Resident at the UTRGV-DHR Internal Medicine program and is interested in pursuing a fellowship in Endocrinology.

Fatimah O. Bello

Resident
University of Texas RGV-DHR
Edinburg, Texas

Fatimah Bello is a 2nd year Internal Medicine Resident and is interested in pursuing an Endocrinology fellowship.

Fatimah O. Bello

Resident
University of Texas RGV-DHR
Edinburg, Texas

Fatimah Bello is a 2nd year Internal Medicine Resident and is interested in pursuing an Endocrinology fellowship.

Leonardo Pozo Garcia

Resident
University of Texas RGV-DHR
McAllen, Texas

Leonardo is a first year Internal Medicine Resident at the UTRGV-DHR Internal Medicine program and is interested in pursuing a fellowship in Endocrinology.