Quest Diagnostics is set to provide a molecular test to help physicians determine if a thyroid gland is cancerous and requires surgical removal. In addition, the company has introduced the Quest Diagnostics Thyroglobulin (Tg) Post-treatment Monitoring Test to aid in monitoring for recurrence of cancer following surgery.
The Thyroid Cancer Mutation Panel can reportedly identify mutations associated with four gene markers indicated by the American Thyroid Association for the clinical management of indeterminate thyroid biopsies. The markers are BRAF V600E, RAS, RET/PTC, and PAX8/PPAR gamma, which are associated with papillary and follicular thyroid cancer.
“The removal of a healthy thyroid gland is an unfortunate outcome for many patients, due to limitations of current test methods,” notes Richard E. Reitz, M.D., medical director and chair, endocrine division, Quest Diagnostics Nichols Institute. “We believe our molecular panel will enhance the reliability of thyroid biopsy testing, helping to prevent the unnecessary removal of healthy thyroids for many patients.”
The test complements the company’s fine needle aspiration (FNA) cytology testing services for thyroid biopsies and may be used on FNA biopsies ruled indeterminate by these testing services. Approximately 15% to 20% of these biopsies, which are collected by FNA, produce indeterminate results, according to Quest Diagnostics.
Results of a study by scientists at Quest Diagnostics found that 90 of 149 FNA specimens, or about 60%, had mutations of one or more of the four markers tested by the new panel. The presence of the four markers was generally mutually exclusive, suggesting potential value in a hierarchical screening strategy for samples with limited tissue. According to the American Cancer Society, about two tests in every 10 may need to be repeated because the sample does not contain enough cells for testing.
With regard to its recurrence test, Quest Diagnostics explains that thyroid cancers can cause blood levels of Tg to rise, providing a marker for disease return. However, these cancers can also cause auto-antibodies (anti-TG) to rise, hindering reliable Tg measurement in 20% to 30% of cases. The new Quest Diagnostics test is believed to be the first for clinical use to use liquid chromatography tandem mass spectrometry (LC/MS/MS) to confirm and measure Tg in anti-TG positive specimens tested by immunoassays.