Prospective Validation of ThyroSPEC Molecular Testing of Indeterminate Thyroid Nodule Cytology Following Diagnostic Pathway Optimization

Development of a Nomogram to Integrate Molecular Testing and Clinical Variables to Improve Malignancy Risk Assessment Among Cytologically Indeterminate Thyroid Nodules

Background: The introduction of molecular testing (MT) of cytologically indeterminate thyroid nodules (ITNs) alone has not impacted thyroidectomy rates. Due to this, we evaluated the incremental diagnostic value of various clinical variables in addition to MT results, in predicting the risk of malignancy (ROM) among ITNs. Methods: This prospective observational study included 1024 consecutive ITNs that underwent reflexive ThyroSPEC MT between Jul 30, 2020, and Oct 30, 2023. A multivariable logistic regression model was built to assess the relationship between histology outcomes and clinical variables, including nodule discovery by palpation, ultrasound risk categories, maximum nodule size, Bethesda category, Bethesda atypia, and ThyroSPEC categories. A total of 332 out of 1024 patients who underwent surgery and had complete data for all variables were included in the model. A nomogram was subsequently developed based on the model. Results: The model achieved a cross-validated AUC of 0.831 (95% confidence intervals: 0.787-0.874). Patients with high-risk mutations or malignant molecular markers exhibited significantly higher odds (152.79 times) of malignancy compared to those with mutation-negative or benign molecular marker results. Patients with maximum nodule size >5 cm have 4.34 times higher odds of malignancy than those 0-2 cm. The presence of nuclear atypia increased the odds of malignancy by 4.26 times, while ultrasound malignancy risk category 5 increased the odds of malignancy by 2.89 times compared to categories 1-3. Positive palpation discovery increased the odds by 1.83 times. The integrated ROM estimated from the regression model is significantly associated with the surgery type (p < 0.001). In the low (0-30%) and intermediate ROM (31-70%) categories, lobectomy alone is the most common surgery (61% and 70%, respectively), while in the high ROM (>70%) category, total thyroidectomy dominates (62%). Conclusions: Although MT alone played an important role in decision-making regarding surveillance versus surgery in our study population, integrating MT results with additional clinical variables improved the malignancy risk prediction for ITNs. Our results highlight the importance of contextualizing MT results within an integrated interdisciplinary thyroid nodule diagnostic pathway.

Ultrasound radiomics and genomics improve the diagnosis of cytologically indeterminate thyroid nodules

Background

Increasing numbers of cytologically indeterminate thyroid nodules (ITNs) present challenges for preoperative diagnosis, often leading to unnecessary diagnostic surgical procedures for nodules that prove benign. Research in ultrasound radiomics and genomic testing leverages high-throughput data and image or sequence algorithms to establish assisted models or testing panels for ITN diagnosis. Many radiomics models now demonstrate diagnostic accuracy above 80% and sensitivity over 90%, surpassing the performance of less experienced radiologists and, in some cases, matching the accuracy of experienced radiologists. Molecular testing panels have helped clinicians achieve accurate diagnoses of ITNs, preventing unnecessary diagnostic surgical procedures in 42%-61% of patients with benign nodules.

Objective

In this review, we examined studies on ultrasound radiomics and genomic molecular testing for cytological ITNs conducted over the past 5 years, aiming to provide insights for researchers focused on improving ITN diagnosis.

Conclusion

Radiomics models and molecular testing have enhanced diagnostic accuracy before surgery and reduced unnecessary diagnostic surgical procedures for ITN patients.

Thyroid nodules: diagnosis and management

Thyroid nodules, with a prevalence of almost 25% in the general population, are a common occurrence. Their prevalence varies considerably depending on demographics such as age and sex as well as the presence of risk factors. This article provides a comprehensive overview of the prevalence, risk stratification and current management strategies for thyroid nodules, with a particular focus on changes in diagnostic and therapeutic protocols that have occurred over the past 10 years. Several sonography-based stratification systems (such as Thyroid Imaging Reporting and Data Systems (TIRADS)) might help to predict the malignancy risk of nodules, potentially eliminating the need for biopsy in many instances. However, large or suspicious nodules necessitate cytological evaluation following fine-needle aspiration biopsy for accurate classification. In the case of cytology yielding indeterminate results, additional tools, such as molecular testing, can assist in guiding the management plan. Surgery is no longer the only treatment for symptomatic or malignant nodules: active surveillance or local ablative treatments might be beneficial for appropriately selected patients. To enhance clinician-patient interactions and discussions about diagnostic options, shared decision-making tools have been developed. A personalized, risk-based protocol promotes high-quality care while minimizing costs and unnecessary testing.

Performance of a multigene genomic classifier and clinical parameters in predicting malignancy in a Southeast Asian cohort of patients with cytologically indeterminate thyroid nodules

BACKGROUND

Most thyroid nodules are benign. It is important to determine the likelihood of malignancy in such nodules to avoid unnecessary surgery. The primary objective of this study was to characterize the genetic landscape and the performance of a multigene genomic classifier in fine-needle aspiration (FNA) biopsies of cytologically indeterminate thyroid nodules in a Southeast Asian cohort. The secondary objective was to assess the predictive contribution of clinical characteristics to thyroid malignancy.

METHODS

This prospective, multicenter, blinded study included 132 patients with 134 nodules. Molecular testing (MT) with ThyroSeq v3 was performed on clinical or ex-vivo FNA samples. Centralized pathology review also was performed.

RESULTS

Of 134 nodules, consisting of 61% Bethesda category III, 20% category IV, and 19% category V cytology, and 56% were histologically malignant. ThyroSeq yielded negative results in 37.3% of all FNA samples and in 42% of Bethesda category III-IV cytology nodules. Most positive samples had RAS-like (41.7%), followed by BRAF-like (22.6%), and high-risk (17.9%) alterations. Compared with North American patients, the authors observed a higher proportion of RAS-like mutations, specifically NRAS, in Bethesda categories III and IV and more BRAF-like mutations in Bethesda category III. The test had sensitivity, specificity, negative predictive value, and positive predictive value of 89.6%, 73.7%, 84.0%, and 82.1%, respectively. The risk of malignancy was predicted by positive MT and high-suspicion ultrasound characteristics according to American Thyroid Association criteria.

CONCLUSIONS

Even in the current Southeast Asian cohort with nodules that had a high pretest cancer probability, MT could lead to potential avoidance of diagnostic surgery in 42% of patients with Bethesda category III-IV nodules. MT positivity was a stronger predictor of malignancy than clinical parameters.

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).