Also known as: Thyroid molecular testing; thyroid nodule molecular panel; ThyroSeq v3 Genomic Classifier; ThyroSeq Cancer Risk Classifier (CRC).
Oncology - Thyroid nodules
Use of test
The cytology of a fine needle aspirate (FNA) from a thyroid nodule is reported using the RCPA/ASC (Australasian) modified Bethesda system. Most FNA results can be confidently designated as benign (Category 2) or malignant (Category 6), with clear consequences for subsequent decision-making. However, the FNAs from approximately one-third of nodules do not provide a definitive diagnosis and are designated indeterminate (Category 3; 3-20% of FNAs), suspicious for neoplasm (Category 4; ~10%) or suspicious for malignancy (Category 5; ~2-3%).
The ThyroSeq® Genomic Classifier uses genetic analysis of the FNA to clarify the risk of malignancy in nodules with Category 3-5 cytology.
ThyroSeq can also be used in malignant nodules (Category 6) to assess the risk of recurrence and the need for adjuvant therapy such as radioactive iodine and targeted therapies.
A negative (benign) result allows the patient to avoid unnecessary surgery. A positive result provides valuable information to guide definitive treatment. ThyroSeq has a sensitivity of 94% and a specificity of 82% for thyroid malignancy, yielding the highest positive predictive value (66%) and negative predictive value (97%) among well-validated tests that profile genomic changes in thyroid nodules.
Optimal systemic therapy for advanced thyroid carcinoma is an area of active investigation. The identification of therapeutic targets by ThyroSeq may assist patients and their doctors identify and access the optimal treatment or clinical trial for a patient.
This assay is designed to detect non-heritable mutations. It typically does not raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient. However, some germline mutations may be detected by this assay, and the test cannot differentiate these from somatic mutations. If the clinician suspects on clinical grounds that a mutation identified by ThyroSeq is familial, referral of the patient to a Clinical Genetics service or Familial Cancer Centre is recommended.
ThyroSeq uses next-generation sequencing to interrogate 112 thyroid-related genes for four main classes of molecular alterations, including point mutations, gene fusions, copy number alterations, and gene expression alterations. These genes include potential targetable mutations (including BRAF, RAS, RET, NTRK, ALK, MET, ROS-1 and PPARG). These results then undergo analysis utilising a unique genomic classifier, assessing the mutations present and associated risk of malignancy. ThyroSeq has been validated in a large prospective, double-blind multicentre study. For further details, please refer to the ThyroSeq website.
ThyroSeq is performed through our sister Sonic laboratory in the US. Please refer to the Sonic Healthcare Australian Privacy Guidelines regarding the handling of identified samples and information sent from Australia to an overseas laboratory for testing.
Requesting the test
This test is usually requested by a medical specialist.
Specialists should order this for a patient in consultation with a cytopathologist or histopathologist at the local Sonic pathology practice. They will provide the specialist with a specific request form that fulfils the requirements of the testing laboratory in the US; they can also prepare the patient’s samples for shipping (if that is held by the Sonic practice).
Direct smear preparations, preferably fixed slides, with greater than 300 lesional cells present.
Formalin-fixed, paraffin embedded tissue or cells (FFPE) - 12 sections of 4 micron thickness, dried overnight at 37°C onto charged/coated slides. Please label each slide with patient and block identifiers, and number them sequentially 1-12. Stain slides 1 and 12 with H&E and leave slides 2-11 unstained.
The request should be accompanied by the ThyrsoSeq request form and a copy of the original cytopathology report.
14 business days from receipt of sections by the testing laboratory in the US.
(AUD) $2,100 for a single nodule
(AUD) $1,164 for each additional nodule (when tested at the same time)