AFIRMA GEC: MOLECULAR ANALYSIS IN FOLLICULAR THYROID NODULES
Afirma GEC is a gene profiling method able to determine the benign nature of a thyroid nodule and to avoid surgery for the patient with indeterminate thyroid nodule (THY3, Bethesda III or IV).
Thyroid needle aspiration (Fine Needle Aspiration, FNA) allows, in most cases, a definitive diagnosis about thyroid nodule nature. Therefore, a thyroid lesion can be classified as benign or malignant. However, cytology is not able to make this distinction in about 20% of cases. This is the case of nodules with indeterminate cytology (Thy 3a or Thy3f according to British Classification, or Bethesda III (AUS/FLUS) and Bethesda IV (Suspicious for Follicular Neoplasm) accordind to Bethesda Classification. In these cases, the cells present in a benign nodule are substantially indistinguishable from those found in the cancer and only its surgical removal allows a definite definitive diagnosis (with histological examination). Generally, for indeterminate thyroid nodules, surgery is often recommended due to the likelihood that follicular proliferation hides a thyroid tumor. However, it is known that after surgery, as many as 80% of the indeterminate nodules will result to be benign and only 20% malignant. In summary, it is very likely that a patient with an indeterminate nodule will undergo surgery “unnecessarily”.
In order to reduce the number of “unnecessary” surgical interventions, ultrasound methods (elastosonography), immunohistochemistry (galectin-3, HBME-1), genetic mutations (mutations and rearrangements of BRAF, RET/PCT) or molecular genetic tests were evaluated, the last representig the most promising methods.
In this context, the most studied method of gene profiling is Afirma, that is able to determine, with high reliability, the benignity of a cytologically indeterminate thyroid nodule. This method has a negative predictive value of 95%. Basically, if a lesion result to be benign by Afirma, it is very likely that the nodule is really benign (with a > 95% probability, about the same probability that a Thy2 nodule has to be benign).
According to experts, such a high negative predictive value is a sufficient condition for: a) considering a benign nodule with Afirma totally similar to a benign nodule of traditional cytology (Thy2); b) replacing the usual use of surgery with clinical and ultrasonographic follow-up.
To better understand the mechanism on which Afirma is based, it is useful to know some concepts: first of all, what is gene expression. Gene expression is the process by which information encoded in a gene is translated into structures in the cell (proteins, metabolites or ribonucleic acid as RNA). The evaluation of gene expression profiles (GEP) is able to simultaneously study multiple genes and to evaluate how many oth them are activated (or not) based on the production of RNA and proteins present in the tissue. By simultaneously measuring the RNA levels of thousands of genes, GEP is able to provide a snapshot of the gene expression rate in a specific tissue sample. So a gene expression test is not a simple genetic test.
Genetic testing can help evaluate the individual risk of developing a disease in the future. In contrast, gene expression tests measure RNA activity in a body tissue/fluid at a given point in life. Since gene expression (and therefore RNA levels) are dynamic and change as a result of pathological processes or environmental factors, these gene activity patterns can be used to diagnose a disease and to evaluate the effect of therapies in the time.
In the thyroid field, the Afirma Gene Expressione Classifier (Afirma GEC) measures the gene expression of as many as 142 genes and is able to assess any genetic alterations associated with thyroid cancer and thus to distinguish cytologically indeterminate thyroid nodules in two categories: benign and suspicious malignant nodules. Basically it is a gene profiling test able to biologically stratify the risk of cancer in an indeterminate (Thy3a, Thy3f, Bethesda III or Bethesda IV) thyroid nodule and to select patients who are at very low risk of having a tumor (<5%). This is therefore an exclusion test (rule-out). If a nodule is benign to Afirma, malignancy can practically be almost excluded, and therefore the patient can definitely avoid surgery.
The first prospective multicenter study on Afirma was published by Alexander (2012) in a prestigious scientific journal (New England Journal Medicine) and showed that Afirma gene expression classifier (GEC) correctly identifies benign nodules with a very high negative predictive value in thyroid nodules larger than 1 cm. Other studies have confirmed these data, demonstrated its validity and clinical applicability (Walsh 2012) and showed that the use of Afirma had reduced the number of unnecessary surgical interventions (Duik 2012).
Diagnsotic performanece of Afirma has been even increased by its last advanced version (Afirma GSC, Genomic Sequencing Classifier) and Afirma GSC X Atlas (Expression Atlas).
In conclusion, Afirma GSC X Atlas represents the most advanced method currently available worldwide for the genomic analysis of indeterminate thyroid nodules (Thy 3a, Thy3f, Bethesda III (AUS/FLUS), Bethesda IV).
Afirma, provides two possible results on indeterminate thyroid nodules: benign or suspicious for malignant. Afirma GSC, by reclassifying cytologically indeterminate thyroid nodules as benign, avoids unnecessary thyroid surgery and is useful in management of cytologically indeterminate thyroid nodules.
Afirma was developed in the United States and, from the first studies, now it is widespread to other countries.
The EndocrinologiaOggi Center in Rome (Italy), is the first center in Europe where Afirma is clinically and routinately used for stratification of indeterminate thyroid nodules. European patients that prefer a closer place to perform Afirma instead of San Francisco (United States), can do it in Rome (Italy) at a lower price (2400 euros).
For more information about Afirma GSC, click here.
For more information about Afirma GSC X Atlas, click here.
For an appointment for Afirma GSC X Atlas, you can:
– write an email (firstname.lastname@example.org)
– call (0039 0686391386)
– book on line (click here).
Dr. Massimiliano Andrioli
MD, PhD, Endocrinologist
Centro EndocrinologiaOggi, Roma
viale Somalia 33A, Roma
Alexander EK, Kennedy GC, Baloch ZW et al. Preoperative Diagnosis of Benign Thyroid Nodules with Indeterminate Cytology. N Engl J Med. 2012;367:705-715.
Chudova D, Wilde JI, Wang ET, et al. Molecular Classification of Thyroid Nodules Using High-Dimensionality Genomic Data. J Clin Endocrinol Metab 2010;95:5296-5304.
Walsh S, Wilde JI, Tom E, et al. Analytical performance verification of a molecular diagnostic for cytology-indeterminate thyroid nodules. J Clin Endocrinol Metab 2012;97:2297-2306.
Alexander EK, Schorr, M, Klopper J et al. Multi-center clinical experience with the Afirma Gene Expression Classifier. J Clin Endocrinol Metab. 2014;99(1):119-25.
Duick DS, Klopper JP, Diggans JC, et al. The Impact of Benign Gene Expression Classifier Test Results on the Endocrinologist-Patient Decision to Operate on Patients with Thyroid Nodules with Indeterminate FNA Cytopathology, Thyroid. 2012;22(10):996-1001.
Lastra RR, et al. Implications of a suspicious Afirma test result in thyroid fine-needle aspiration cytology: an institutional experience. Cancer Cytopathol. 2014;122(10):737-44.
McIver B, et al. An independent study of a gene expression classifier (Afirma) in the evaluation of cytologically indeterminate thyroid nodules. J Clin Endocrinol Metab. 2014;99(11):4069-77.
Harrell RM, Bimston DN. Surgical utility of Afirma: effects of high cancer prevalence and oncocytic cell types in patients with indeterminate thyroid cytology. Endocr Pract. 2014;20(4)364-9.
Sullivan PS, et al. The impact of atypia/follicular lesion of undetermined significance and repeat fine-needle aspiration: 5 years before and after implementation of the Bethesda System. Cancer Cytopathol 2014;122(12):866-72.
Marti JL, et al. Wide inter-institutional variation in performance of a molecular classifier for indeterminate thyroid nodules. Ann Surg Oncol 2015;22(12):3996-4001.
Brauner E, et al. Performance of the Afirma gene expression classifier in Hurthle Cell thyroid nodules differs from other indeterminate thyroid nodules. Thyroid. 2015;(7):789-96.
Angell TE, et al. Afirma benign thyroid nodules show similar growth to cytologically benign nodules during follow-up. J Clin Endocrinol Metab. 2015;100(11):E1477-83.
Witt RL. Outcome of thyroid gene expression classifier testing in clinical practice. Laryngoscope. 2016 Feb;126(2):524:7.
Celik B, et al. Afirma GEC and Thyroid Lesions: An Institutional Experience. Diagn Cytopathol 2015 Dec;43(12):966-70.
Yang SE, et al. Has Afirma Gene Expression Classifier Test Refined the Indeterminate Thyroid Category in Cytology? Cancer Cytopathol. 2016 Feb;124(2):100-9.
Zhu QL, et al. Relationship between sonographic characteristics and Afirma Gene Expression Classifier results in thyroid nodules with indeterminate fine-needle aspiration cytology. Am J Roentgenol 2015, October; 205(4):861-5.
Wu JX, et al. Effect of malignancy rates of cost-effectiveness of routine gene expression classifier testing for indeterminate thyroid nodules. Surgery. 2016 Jan;159(1):118-29.
Sipos JA, Blevins TC, Shea HC, et al. Long-Term Non-Operative Rate of Thyroid Nodules with Benign Results on the Afirma Gene Expression Classifier. Endocrine Practice. 2016, Jan 20. (Epub ahead of print)
Ward LS, Kloos RT. Molecular markers in the diagnosis of thyroid nodules. Arq Bras Endocrinol Metabol. 2013 Mar;57(2):89-97.
Ali SZ, Fish SA, Lanman R, Randolph GW, Sosa JA. Use of the Afirma® Gene Expression Classifier for Preoperative Identification of Benign Thyroid Nodules with Indeterminate Fine Needle Aspiration Cytopathology. PLOS Currents Evidence on Genomic Tests. 2013;5:1-7.
Mingzhao X, Haugen BR, Schlumberger M. Progress in molecular-based management of differentiated thyroid cancer. The Lancet 2013;381(9871)1058-69.
Kim M, Alexander A. Diagnostic Use Of Molecular Markers In the Evaluation of Thyroid Nodules. Endocrine Practice 2012;18:796-802.
Melillo R, Santoro, M. Molecular Biomarkers in Thyroid FNA Samples. J Clin Endocrinol Metab. 2012; 97(12):43704737.
Duick D. Overview of Molecular Biomarkers for Enhancing The Management of Cytologically Indeterminate Thyroid Nodules and Thyroid Cancer. Endocrine Practice 2012;18:611-615.
Li H, Robinson KA, Anton B, Sadhanha IJ, Ladenson PW. Cost-Effectiveness of a Novel Molecular Test for Cytologically Indeterminate Thyroid Nodules. J Clin Endocrinol Metab 2011;96(11):E1719-E1726.
Mitchell I, Livingston EH, Change AY, et al. Trends in thyroid cancer demographics and surgical therapy in the U.S. Surgery 2007;142:823-828.
Shrime MG, Goldstein DP, Seaberg RM, et al. Cost effective management of low-risk papillary thyroid carcinoma. Arch Otolaryngol Head Neck Surg 2007;133:1245-1253.
Esnaola NF, Cantor SB, Sherman SI, Lee JE, Evans DB. Optimal treatment strategy in patients with papillary thyroid cancer: a decision analysis. Surgery 2001;130:921-930.
Cibas ES, Baloch ZW, Fellegara G, et al. A Prospective Assessment Defining the Limitations of Thyroid Nodule Pathologic Evaluation. Ann Intern Med. 2013;159:325-332.
Bongiovanni M, Spitale A, Faquin WC, Mazzucchelli L, Baloch ZW. The Bethesda System for Reporting Thyroid Cytopathology: A Meta-Analysis. Acta Cytol. 2012;56(4):333-339.
Wang C, Friedman L, Kennedy GC, et al. A Large Multicenter Correlation Study of Thyroid Nodule Cytopathology and Histopathology. Thyroid 2011;21(3):243-251.
VanderLaan PA, Marqusee E, Krane JF. Clinical outcome for atypia of undetermined significance in thyroid fine-needle aspirations: should repeated fna be the preferred initial approach? Am J Clin Pathol. 2011 May;135(5):770-775.
Lewis CM, Chang K-P, Pitman M, Faquin WC, Randolph GW. Thyroid Fine-Needle Aspiration Biopsy: Variability in Reporting. Thyroid 2009;19(7):717-723.
Cibas ES, Syed AZ. NCI Thyroid FNA State of the Science Conference. The Bethesda System For Reporting Thyroid Cytopathology. Am J Clin Pathol. 2009;132:658–665.
Baloch ZW, Cibas ES, Clark DP, et al. The National Cancer Institute Thyroid fine needle aspiration state of thescience conference: a summation. CytoJournal. 2008;5:6:425–437.
Berner A, Sigstad E, Pradhan M, Grøholt KK, Davidson B. Fine-needle aspiration cytology of the thyroid gland: comparative analysis of experience at three hospitals. DiagnCytopathol 2006;34:97–100.
Yeh MW, Demircan O, Ituarte P, Clark OH. False-negative fine-needle aspiration cytology results delay treatment and adversely affect outcome in patients with thyroid carcinoma. Thyroid 2004;14:207–215.
Renshaw A. An estimate of risk of malignancy for a benign diagnosis in thyroid fine-needle aspirates. Cancer Cytopathol. 2010;118(4):190-195.
Elsheikh TM, Asa SL, Chan JK , et al. Interobserver and intraobserver variation among experts in the diagnosis of thyroid follicular lesions with borderline nuclear features of papillary carcinoma. Am J Clinical Pathol 2008;130(5):736–744.
Lloyd RV, Erickson LA, Casey MB, et al. Observer variation in the diagnosis of follicular variant of papillary thyroid carcinoma. Am J Surg Pathol 2004;28:1336–1340.Hirokawa M, Carney JA, Goellner J R, et al. Observer variation of encapsulated follicular lesions of the thyroid gland. Am J Surg Pathol 2002;26:1508–1514.