Preoperative Role of RAS or BRAF K601E in the Guidance of Surgery for Indeterminate Thyroid Nodules

Diagnostic utility of RAS mutation testing for refining cytologically indeterminate thyroid nodules

RAS mutations are prevalent in indeterminate thyroid nodules, but their association with malignancy risk and utility for diagnosis remains unclear. We performed a systematic review and meta-analysis to establish the clinical value of RAS mutation testing for cytologically indeterminate thyroid nodules. PubMed and Embase were systematically searched for relevant studies. Thirty studies comprising 13,328 nodules met the inclusion criteria. Random effects meta-analysis synthesized pooled estimates of RAS mutation rates, risk of malignancy with RAS positivity, and histologic subtype outcomes. The pooled mutation rate was 31 % (95 % CI 19-44 %) among 5,307 indeterminate nodules. NRAS mutations predominated at 67 % compared to HRAS (24 %) and KRAS (12 %). The malignancy rate with RAS mutations was 58 % (95 %CI=48-68 %). RAS positivity increased malignancy risk 1.7-fold (RR 1.68, 95 %CI=1.21-2.34, p=0.002), with significant between-study heterogeneity (I2=89 %). Excluding one outlier study increased the relative risk to 1.75 (95 %CI=1.54-1.98) and I2 to 14 %. Funnel plot asymmetry and Egger's test (p=0.03) indicated potential publication bias. Among RAS-positive malignant nodules, 38.6 % were follicular variant papillary carcinoma, 34.1 % classical variant, and 23.2 % follicular carcinoma. No statistically significant difference in the odds of harboring RAS mutation was found between subtypes. In conclusion, RAS mutation testing demonstrates clinical utility for refining the diagnosis of cytologically indeterminate thyroid nodules. Positivity confers a 1.7-fold increased malignancy risk, supporting use for personalized decision-making regarding surgery vs. monitoring. Follicular variant papillary carcinoma constitutes the most common RAS-positive malignant histological subtype. See also the graphical abstract(Fig. 1).

Risk assessment of cytologically indeterminate thyroid nodules with integrated molecular testing and repeat biopsy: a surgical decision-oriented tool

BACKGROUND

The preoperative diagnosis of cytologically indeterminate thyroid nodules (ITNs) is very challenging. In this study, we aim to provide an integrated risk assessment for thyroid nodules with indeterminate cytology to guide surgical decision-making, which includes results of blood tests, molecular tests, and repeat fine-needle aspiration biopsy (FNAB).

METHODS

The study retrospectively included 265 ITNs between June 2019 and April 2022. According to our integrated risk assessment process that starts with blood testing, followed by supplementary DNA mutation detection on the first FNAB, and finally repeat FNAB, we divided the ITNs into high-risk and low-risk groups. Performance was evaluated with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), area under the receiver operating characteristic curve (AUC), and the consistency between the risk evaluation and histological results.

RESULTS

Of the 265 ITNs, 87 were included in the risk assessment process. The risk assessment had a sensitivity of 84.1%, specificity of 83.3%, PPV of 95.1%, NPV of 57.7%, and AUC of 0.837. The nodules with consistent results between the risk groups and histological outcomes, which included malignant cases in the high-risk group and benign cases in the low-risk group, accounted for 83.9% of all risk-assessed nodules.

CONCLUSIONS

These data suggest that the integrated risk assessment might provide proper information for surgical decision-making in patients with ITNs.

The Significance of RAS-Like Mutations and MicroRNA Profiling in Predicting Malignancy in Thyroid Biopsy Specimens

In cytologically indeterminate thyroid nodules undergoing molecular testing, estimated risk of malignancy is variable. Identification of a non-cancer-specific mutation (RAS-like) confirms a neoplastic process but does not differentiate between benign, malignant, and low-risk neoplasms. This study aims to retrospectively evaluate institutional experience of Interpace (ThyGeNEXT^® and ThyraMIR^®; Pittsburgh, PA) testing and to determine the rate of malignancy in resected nodules, stratified by mutational analysis and microRNA profile. Of 1917 fine need aspirations, 140 (7.3%) underwent Interpace testing: 47 (33.6%) were molecular-not-benign (harbored mutation, fusion, and/or positive miRNA) and 93 (66.4%) were molecular-benign (no mutations or fusions and negative microRNA). Surgery was spared in 79.6% of molecular-benign and 61.4% of all tested patients. Fifty-four (38.6%) underwent resection. Seventeen (89.5%) of the resected molecular-benign were benign and 2 were malignant. Thirteen (37.1%) of the resected molecular-not-benign were benign, 7 (20%) were noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), and 15 (42.9%) were malignant (p < 0.05, negative predictive value (NPV) 89.4-95.6%, positive predictive value (PPV) 22.3-42.8%). Most molecular-not-benign (72.3%) had RAS-like mutation. Twenty-three were resected: 3 were malignant and 7 were NIFTP. Nodules with non-RAS-like mutations (BRAF V600E-like, others) were more likely to be malignant than RAS-like (H/N/KRAS, BRAF K601E) (p < 0.05, NPV 86.9-96.5%, PPV 100%). Most nodules had RAS-like mutations and most were benign or low-risk neoplasms (NIFTP). This study supports the role of histologic examination in the distinction of malignancy in RAS-like thyroid neoplasms and underscores the role of molecular testing in risk stratification, patient counseling, and operative management.

Risk stratification of indeterminate thyroid nodules by novel multigene testing: a study of Asians with a high risk of malignancy

Molecular testing of indeterminate thyroid nodules informs about the presence of point mutations, insertions/deletions, copy number variants, RNA fusions, transcript alterations and miRNA expression. American Thyroid Association (ATA) guidelines suggest molecular testing of indeterminate thyroid nodules may be considered to supplement risk of malignancy (ROM). Although these recommendations have been incorporated in clinical practices in the US, molecular testing of indeterminate thyroid nodules isn't common practice in Asia. Here, we performed molecular testing of 140 indeterminate nodules from Chinese patients using a novel molecular platform composed of RNA and DNA-RNA classifiers, which is similar to Afirma GEC and ThyroSeq v3. Compared with reports from North America, the new RNA and DNA-RNA classifiers had a higher positive predictive value (p1=0.000, p2=0.020) but a lower negative predictive value (p1=0.004, p2=0.098), with no significant differences in sensitivity (p1=0.625, p2=0.179) or specificity (p1=0.391, p2=0.264). Out of 58 resected nodules, 10 were borderline and 33 malignant, indicating a 74.1% ROM, which was higher than reports in North America (10-40% ROM). Our findings emphasize molecular testing with the newly-reported RNA and DNA-RNA classifiers can be used as a "rule-in" test when ROM is high.

Feasibility and performance of the Idylla™ NRAS/BRAF cartridge mutation assay on thyroid liquid-based fine-needle aspiration

BACKGROUND

Thyroid nodules with indeterminate cytology represent up to 30% of cases. Molecular testing is now highly recommended to improve management. This study aimed to evaluate the use of the Idylla™ NRAS/BRAF mutation test, a rapid and automated polymerase chain reaction (PCR) assay validated for fixed paraffin-embedded use, on residual thyroid liquid-based fine-needle aspiration (LB-FNA).

METHODS

Concordance between mutations detected by the Idylla™ assay and the gold-standard qPCR was assessed by splitting in two aliquots 31 BRAF or RAS mutated and 5 non-mutated LB-FNA samples. Samples were obtained either from simulated FNA after thyroidectomy or from FNA obtained during routine care. A third aliquot was used to assess the limit of detection of Idylla™ for five mutated samples.

RESULTS

The Idylla™ assay showed a sensitivity of 97% and a specificity of 83% as results were concordant for 34 out of 36 samples. One discordant sample concerned a BRAF p.K601E-mutation which is not detected by the Idylla™ cartridge. The other showed a false-positive NRAS p.A146T detection and a weak BRAF p.V600E detection. The limit of detection of the Idylla™ assay was not reached by the dilution assay.

CONCLUSION

Idylla™ NRAS/BRAF mutation testing can be performed on residual thyroid LB-FNA, using low DNA quantity input, thus not requiring a dedicated sample. The Idylla™ NRAS/BRAF assay offers a quick and easy first step for analyzing the main molecular alterations in indeterminate thyroid nodules, hence improving diagnostic management.

Preoperative Molecular Testing of Thyroid Nodules: Current Concepts

Robust molecular testing is commercially available for adjuvant assessment of cytologically indeterminate thyroid nodules. Testing has been developed and optimized for fine needle aspiration biopsy collections of thyroid nodules typically under ultrasound evaluation. These assays use a combination of gene expression and/or DNA and RNA assessments for molecular alterations to stratify indeterminate thyroid nodules as benign with risk level similar to benign cytologic read or suspicious with increased risk of malignancy. Guidelines for when to consider adjuvant molecular testing will be discussed.

Molecular Genetics of Follicular-Derived Thyroid Cancer

Simple Summary

Thyroid tumors that derive from follicular cells are not a homogeneous entity, showing variable morphological appearance and different degrees of differentiation. Molecular markers are useful for both diagnostic purposes and prognostic stratification of patients. In presurgical setting, molecular testing of indeterminate thyroid nodules on aspirates provides useful diagnostic information; the molecular analysis on tumor tissues can also reveal the presence of genetic alterations related to patients’ prognosis. In recent years, the molecular characterization of these tumors has acquired even more importance thanks to the introduction of targeted drugs. This review summarizes the current literature on the molecular landscape of follicular-derived thyroid tumors.

Abstract

Thyroid cancer is the most common type of endocrine-related malignancy, whose incidence rates have increased dramatically in the last few decades. Neoplasms of follicular origin generally have excellent prognosis, with the exception of less differentiated tumors. Follicular-derived thyroid cancer can manifest as a variety of morphologically distinct entities, characterized by various degrees of differentiation and invasiveness. Histological evaluation is thus crucial for the definition of patients’ prognosis. However, within each histological subtype, tumor behavior can be highly variable, and, in this respect, molecular characterization can provide insightful information to refine the risk stratification of tumors. In addition to the importance of its prognostic role, molecular testing can be used to support the differential diagnosis of thyroid nodules in the absence of marked cyto-morphological aberrations. Finally, with the advent of targeted drugs, the presence of molecular alterations will guide the therapeutic strategies for patients with advanced tumors who do not respond to standard treatment. This review aims to describe the genetic landscape of follicular-derived thyroid tumors also highlighting differences across histological subtypes.

Risk assessment for distant metastasis in differentiated thyroid cancer using molecular profiling: A matched case-control study

Background

Risk stratification for patients with differentiated thyroid cancer (DTC) is based primarily on pathologic tumor characteristics. Accurate preoperative prognostication could allow for more informed initial surgical recommendations, particularly among patients at a higher risk for distant metastasis (DM). The objective of this study was to characterize the genetic profile of DTC with DM and to validate a molecular‐based risk stratification.

Methods

A case‐control study design was used to analyze patients who had DTC with DM (n = 62) and a propensity matched cohort of patients who had DTC without DM after at least 5 years of follow‐up using the ThyroSeq version 3 targeted next‐generation sequencing assay. The results were classified into high‐risk, intermediate‐risk, and low‐risk of aggressive disease.

Results

Most patients who had DTC with DM (66%) had a late‐hit mutation in TERT, TP53, or PIK3CA. After propensity matching by age, tumor size, and sex, the high‐risk molecular profile had strong association with DM (high‐risk vs intermediate‐risk: odds ratio, 25.1; 95% CI, 3.07‐204.4; P < .001; high‐risk vs low‐risk: odds ratio, 122.5; 95% CI, 14.5‐1038.4; P < .001). Overall, molecular risk categories were associated with DM risk, with a concordance index of 0.836 (95% CI, 0.759‐0.913), which remained consistent after internal validation. Within the range of 5% to 10% of DM observed in DTC, the expected probability of DM would be 0.2% to 0.4% for the low‐risk molecular profile, 4.7% to 9.4% for the intermediate‐risk molecular profile, and 19.3% to 33.5% for the high‐risk molecular profile.

Conclusions

In this matched case‐control study, genetic profiling using an available molecular assay provided accurate and robust risk stratification for DM in patients with DTC. The availability of preoperative prognostication may allow tailoring treatment for patients with DTC.

In this matched case‐control study, comprehensive genetic profiling provides accurate and robust risk stratification for distant metastasis in patients with differentiated thyroid cancer. The availability of preoperative prognostication may allow for molecular‐directed treatment recommendations to tailor care for these patients.

Cytological features and nuclear scores: Diagnostic tools in preoperative fine needle aspiration of indeterminate thyroid nodules with RAS or BRAF K601E mutations?

INTRODUCTION

The cytological diagnosis of follicular-patterned thyroid lesions is challenging, especially since the World Health Organisation classification has recognised non-invasive follicular thyroid neoplasm with papillary-like features. These entities are often classified as indeterminate on cytology. Molecular testing has been proposed to help classify indeterminate nodules. RAS and K601E BRAF mutations are mostly encountered in follicular-patterned lesions, but their diagnostic value is not well established. Nuclear scores have also been proposed to help classify indeterminate lesions.

OBJECTIVE

To investigate the correlation between cytological features and histology and to assess nuclear scores in a series of indeterminate RAS or BRAF K601E positive thyroid nodules.

METHODS

The cytological parameters of 69 indeterminate RAS or BRAF K601E-positive thyroid nodules were evaluated. The Strickland and Maletta scores and a new nuclear score were assessed. Diagnosis of malignant, benign or indolent neoplasms was confirmed in each case by histology. Malignant and indolent nodules were considered surgical nodules, and adenomas non-surgical nodule.

RESULTS

Surgical nodules were associated with the presence of ground glass nuclei (P = .001), grooves (P < .001) or irregular nuclear membranes (P = .01) on cytology. Nuclear scores were more often ≥2 in surgical nodules compared to benign ones (P < .001), with high sensitivity, but a low negative predictive value.

CONCLUSIONS

Analysis of nuclear features is useful to distinguish non-surgical from surgical nodules in indeterminate FNAs. Although nuclear scores are not ideal rule-out tests for indeterminate RAS or BRAF K601E positive nodules, they seem useful to screen non-molecular tested or non-mutated indeterminate FNAs. This work shows that meticulous analysis of nuclear features on cytological specimens can be useful to distinguish non-surgical nodules (adenoma) from surgical nodules in indeterminate FNAs. Although nuclear scores are not rule-out tests for indeterminate RAS or BRAF K601E positive nodules, they are useful in screening non-molecular tested or non-mutated indeterminate FNAs for surgery.