Bethesda III and IV Thyroid Nodules Managed Nonoperatively After Molecular Testing With Afirma GSC or Thyroseq v3.

CONTEXT: Molecular testing has improved risk stratification and increased nonoperative management for patients with indeterminate thyroid nodules, but data on the long-term outcomes of current molecular tests Afirma Gene Sequencing Classifier (GSC) and Thyroseq v3 are limited. OBJECTIVE: To determine the rate of delayed operation and the false negative rate of the Afirma GSC and Thyroseq v3 in Bethesda III and IV thyroid nodules. METHODS: Prospective follow-up of a single center, randomized, clinical trial comparing the performance of Afirma GSC and Thyroseq v3 in the diagnosis of indeterminate thyroid nodules at the University of California, Los Angeles (UCLA). Consecutive participants who underwent thyroid biopsy in the UCLA health system with Bethesda III and IV cytology from August 2017 to November 2019. The main outcome measure was false negative rate of molecular testing. RESULTS: Of 176 indeterminate nodules with negative or benign molecular test results, 14 (8%) nodules underwent immediate resection, with no malignancies found on surgical pathology. Nonoperative management with active surveillance was pursued for 162 (92%) nodules with benign or negative test results. The median surveillance was 34 months (range 12-60 months), and 44 patients were lost to follow-up. Of 15 nodules resected during surveillance, 1 malignancy was found (overall false negative rate of 0.6%). This was a 2.7 cm minimally invasive Hurthle cell carcinoma that initially tested negative with Thyroseq v3 and underwent delayed resection due to sonographic growth during surveillance. CONCLUSIONS: The majority of Bethesda III/IV thyroid nodules with negative or benign molecular test results are stable over 3 years of follow-up. These findings support the high sensitivity of current molecular tests and their role in ruling out malignancy in indeterminate thyroid nodules.

Systemic light-chain amyloidosis incidentally diagnosed after subtotal parathyroidectomy and thyroid lobectomy.

A 74-year-old woman with a history of primary hyperparathyroidism, thyroid nodules, atrial fibrillation and pacemaker placement for sick sinus syndrome presented with fatigue, constipation and persistent lower extremity oedema. She underwent subtotal parathyroidectomy and left thyroid lobectomy. Histopathology revealed amyloidosis affecting the thyroidand parathyroids confirmed by Congo Red Staining with Mayo Clinic subtyping of light chain kappa-type amyloidosis. She was found to have combined systolic and diastolic cardiac dysfunction, carpal tunnel neuropathy and pre-diabetes suggestive of systemic amyloidosis with involvement of the heart, nerves and pancreas. Congo red stain was positive for amyloidosis on bone marrow biopsy suggestive of a diagnosis of systemic amyloidosis. She was treated with daratumumab with good clinical response. This case illustrates the necessity of considering systemic amyloidosis in patients with incidentally discovered diffuse amyloid deposits on biopsy of an endocrine organ, as endocrine effects are a rare but likely underdiagnosed consequence of systemic amyloidosis.

Effectiveness of Molecular Testing Techniques for Diagnosis of Indeterminate Thyroid Nodules: A Randomized Clinical Trial.

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 PARTICIPANTS: This 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. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02681328.

Gene Expression Classifier vs Targeted Next-Generation Sequencing in the Management of Indeterminate Thyroid Nodules.

Context: Molecular testing has reduced the need for diagnostic hemithyroidectomy for indeterminate thyroid nodules. No studies have directly compared molecular testing techniques. Objective: Compare the diagnostic performance of Afirma Gene Expression Classifier (GEC) with that of ThyroSeq v2 next-generation sequencing assay. Design: Parallel randomized trial, monthly block randomization of patients with Bethesda III/IV cytology to GEC or ThyroSeq v2. Setting: University of California, Los Angeles. Participants: Patients who underwent thyroid biopsy (April 2016 to June 2017). Intervention: Testing with GEC or ThyroSeq v2. Main Outcome Measure: Molecular test performance. Results: Of 1372 thyroid nodules, 176 (13%) had indeterminate cytology and 149 of 157 eligible indeterminate nodules (95%) were included in the study. Of nodules tested with GEC, 49% were suspicious, 43% were benign, and 9% were insufficient. Of nodules tested with ThyroSeq v2, 19% were mutation positive, 77% were mutation negative, and 4% were insufficient. The specificities of GEC and ThyroSeq v2 were 66% and 91%, respectively (P = 0.002); the positive predictive values of GEC and ThyroSeq v2 were 39% and 57%, respectively. Diagnostic hemithyroidectomy was avoided in 28 patients tested with GEC (39%) and 49 patients tested with ThyroSeq v2 (62%). Surveillance ultrasonography was available for 46 nodules (45 remained stable). Conclusions: ThyroSeq v2 had higher specificity than Afirma GEC and allowed more patients to avoid surgery. Long-term surveillance is necessary to assess the false-negative rate of these particular molecular tests. Further studies are required for comparison with other available molecular diagnostics and for newer tests as they are developed.

Clinical Factors Influencing the Performance of Gene Expression Classifier Testing in Indeterminate Thyroid Nodules.

BACKGROUND: Molecular diagnostic testing is increasingly used in the management of indeterminate thyroid nodules. Limited data exist regarding the influence of clinical factors on gene expression classifier (GEC) test performance. This study examined the positive and negative predictive value of GEC as stratified by nodule size. METHODS: A prospectively maintained pathology database from a single tertiary referral center was queried from 2012 to 2015 for indeterminate thyroid nodules that underwent GEC testing. Nodule size, patient demographics, Bethesda classification, and Hürthle cell-predominant nodules (HCNs) were evaluated as predictors of GEC performance. RESULTS: Two hundred and thirty-one patients with 245 indeterminate nodules were examined. Assuming all nodules to be benign unless proven malignant on histopathology, the sensitivity and specificity of GEC testing were 95.2% and 60.1%, respectively. The malignancy rate among resected nodules was 25.3%. The positive predictive value was consistent across nodule sizes: 45.5% for nodules <1 cm, 42.9% for nodules 1-1.9 cm, 36.0% for nodules 2-2.9 cm, 54.2% for nodules 3-3.9 cm, and 50.0% for nodules ≥4 cm. The negative predictive value ranged from 93.3% to 100% and was not affected by nodule size. HCNs had a high rate of GEC suspicious results (77.4% vs. 50.5% for nodules without Hürthle cell predominance, p < 0.01), though this did not correspond to a difference in the rate of malignancy (25.8% vs. 25.3%). CONCLUSIONS: Nodule size did not affect GEC test performance in the present cohort. GEC benign results remain reliable in large nodules. GEC suspicious nodules >3 cm carry a similar risk of malignancy compared to smaller nodules, and do not warrant more aggressive treatment. GEC testing has limited clinical utility for HCNs due to the high rate of false-positive results.