Effectiveness of Molecular Testing Techniques for Diagnosis of Indeterminate Thyroid Nodules

Abstract

IMPORTANCE Approximately 20% of thyroid nodules display indeterminate cytology. Molecular testing can refine the risk of malignancy and reduce the need for diagnostic hemithyroidectomy.OBJECTIVE To compare the diagnostic performance between an RNA test (Afirma genomic sequencing classifier) and DNA-RNA test (ThyroSeq v3 multigene genomic classifier). DESIGN, SETTING, AND PARTICIPANTSThis parallel randomized clinical trial of monthly block randomization included patients in the UCLA Health system who underwent thyroid biopsy from August 2017 to January 2020 with indeterminate cytology (Bethesda System for Reporting Thyroid Cytopathology category III or IV). INTERVENTIONS Molecular testing with the RNA test or DNA-RNA test. MAIN OUTCOMES AND MEASURES Diagnostic test performance of the RNA test compared with the DNA-RNA test. The secondary outcome was comparison of test performance with prior versions of the molecular tests. RESULTS Of 2368 patients, 397 were eligible for inclusion based on indeterminate cytology, and 346 (median [interquartile range] age, 55 [44-67] years; 266 [76.9%] women) were randomized to 1 of the 2 tests. In the total cohort assessed for eligibility, 3140 thyroid nodules were assessed, and 427 (13.6%) nodules were cytologically indeterminate. The prevalence of malignancy was 20% among indeterminate nodules. The benign call rate was 53% (95% CI, 47%-61%) for the RNA test and 61% (95% CI, 53%-68%) for the DNA-RNA test. The specificities of the RNA test and DNA-RNA test were 80% (95% CI, 72%-86%) and 85% (95% CI, 77%-91%), respectively (P = .33); the positive predictive values (PPV) of the RNA test and DNA-RNA test were 53% (95% CI, 40%-67%) and 63% (95% CI, 48%-77%), respectively (P = .33). The RNA test exhibited a higher PPV compared with the prior test version (Afirma gene expression classifier) (54% [95% CI, 40%-67%] vs 38% [95% CI, 27%-48%]; P = .01). The DNA-RNA test had no statistically significant difference in PPV compared with its prior version (ThyroSeq v2 next-generation sequencing) (63% [95% CI, 48%-77%] vs 58% [95% CI, 43%-73%]; P = .75). Diagnostic thyroidectomy was avoided in 87 (51%) patients tested with the RNA test and 83 (49%) patients tested with the DNA-RNA test. Surveillance ultrasonography was available for 90 nodules, of which 85 (94%) remained stable over a median of 12 months follow-up.CONCLUSIONS AND RELEVANCE Both the RNA test and DNA-RNA test displayed high specificity and allowed 49% of patients with indeterminate nodules to avoid diagnostic surgery. Although previous trials demonstrated that the prior version of the DNA-RNA test was more specific than the prior version of the RNA test, the current molecular test techniques have no statistically significant difference in performance.

Molecular Genetics of Follicular-Derived Thyroid Cancer

“…Thanks to the advent of multitarget platforms (e.g., the nCounter nanoString platform), the most recent scientific approaches have been investigating gene panels able to identify peculiar expression patterns, rather than single markers [ 51 ]. This analysis strategy, in conjunction with mutation analysis, is applied to the differential diagnosis of indeterminate thyroid nodules by diagnostic commercial tests such as the Afirma Genomic Sequencing Classifier and the Thyroseq v3 Genomic Classifier [ 52 ].…”

Thyroid and Molecular Testing. Advances in Thyroid Molecular Cytopathology

“…As reported by Livhits et al, in a series of 397 indeterminate lesions, the performance of both the RNA test and DNA-RNA test increased specificity and reduced by 49% the number of nodules to avoid diagnostic surgery [124]. Furthermore, neither the RNA test nor DNA-RNA test has statistically significant difference in performance, in sensitivity (100% vs. 97%, respectively), and specificity (80% vs. 85%, respectively) [124].…”

“…Different papers showed that several mutation analysis panels are both diagnostic tests and prognostic markers. As previously described, the different molecular testing, including the Afirma GSC, ThyroSeq, and ThyGenX/ThyroMIR are characterized by different advantages and limitations so that they might contribute to a more precise and tailored management [121][122][123][124]. Nevertheless, it is relevant to assess that molecular testing still represents only an adjunct to be discussed together with valuable clinical information (e.g., nodule ultrasound size and high-risk ultra-sonographic characteristics) and cytomorphology.…”

Best Achievements in Clinical Thyroidology in 2020

“…Recent molecular testing (gene panel tests) have been proposed to reduce the need for diagnostic lobectomy in patients with nodules with indeterminate cytology. Livhits et al [ 17 ] investigated the effectiveness of molecular testing techniques, and in particular sought to determine whether an RNA test (Afirma genomic sequencing classifier) or a DNA-RNA test (ThyroSeq v3 multigene genomic classifier) offered superior performance in estimating the risk of malignancy of thyroid nodules with indeterminate cytology. In their randomized clinical trial of 346 patients with 372 indeterminate thyroid nodules, the prevalence of malignancy was 20%.…”