Appropriate and mindful measurement of serum calcitonin in patients with thyroid nodules. A white paper

Medullary thyroid carcinoma (MTC) is an infrequent thyroid malignancy that is often diagnosed at advanced stage with consequent poor prognosis. Thus, the earlier the diagnosis of MTC, the better the prognosis. Unfortunately, the preoperative detection of MTC remains challenging in clinical practice. In fact, while ultrasound and fine-needle aspiration cytology have suboptimal performance in this context, measuring serum calcitonin (Ctn), fully recognized as the most reliable test to detect MTC, is not universally accepted as routine test in all patients with thyroid nodule(s). The authors of this paper reappraise critically the matter of Ctn measurement in view of the recent advancements in the literature to point out the essential information to be known, and then to prepare an easy-to-use guide for clinicians to appropriately consider the measurement of serum Ctn during clinical practice.

Is the 1mg-dexamethasone suppression test a precise marker of glucocorticoid excess and cardiometabolic risk in patients with adrenal incidentalomas?

AIM

To analyze if the 1mg-dexamethasone suppression test (DST) is a reliable marker of glucocorticoid excess and cardiometabolic risk in patients with adrenal incidentalomas (AIs).

METHODS

Cross-sectional study of patients with nonfunctioning adrenal incidentalomas (NFAIs, defined by cortisol post-DST ≤ 1.8 µg/dL) and patients with autonomous cortisol secretion (ACS, defined by cortisol post-DST > 1.8 µg/Dl). The urinary steroid profile (USP) was determined by gas chromatography coupled to mass spectrometry. Both groups were matched by sex, age and body mass index.

RESULTS

Forty-nine patients with AIs (25 with ACS and 24 with NFAI) were included. As a whole, AIs showed a high excretion of β-cortolone, tetrahydro-11-deoxycortisol (THS), α-cortolone, α-cortol, tetrahydrocortisol (THF) and tetrahydrocortisone (THE). A positive yet modest correlation between post-DST cortisol and total excretion of glucocorticoid metabolites (r = 0.401, P = 0.004) was observed, with the stronger being observed with total THS (r = 0.548, P < 0.001) and THF (r = 0.441, P = 0.002). Some of the metabolites that were elevated in patients with AIs, were higher in patients with ACS-related comorbidities than in those without comorbidities. Post-DST cortisol showed a fair diagnostic accuracy for the prediction of ACS-related comorbidities (AUC 0.767 [95% CI 0.634-0.882]). However, post-DST diagnostic accuracy improved when combined with urinary cortisone, α-cortol, THS and serum DHEAS (0.853 [0.712‒0.954]).

CONCLUSION

The DST has a positive, but modest, correlation with urinary glucocorticoid excretion. Similarly, the diagnostic accuracy of the DST for the prediction of ACS-related comorbidities is only fair, but it may be improved if combined with the results of the USP and serum DHEAS.

SIGNIFICANCE STATEMENT

This is the first study aimed to evaluate if 1mg-dexamethasone suppression test (DST) is a reliable marker of glucocorticoid excess and cardiometabolic risk in patients with adrenal incidentalomas (AIs) and if urinary steroid profile was measured by GS-MS could improve such a prediction. We found a positive yet modest correlation between post-DST cortisol and total excretion of glucocorticoid metabolites, with the stronger being observed with total tetrahydro-11-deoxycortisol (THS) and tetrahydrocortisol. Post-DST cortisol showed a fair diagnostic accuracy for the prediction of ACS-related comorbidities (AUC 0.767). However, post-DST diagnostic accuracy improved when combined with urinary cortisone, α-cortol, THS and serum DHEAS (0.853).

Predictive model for autonomous cortisol secretion development in non-functioning adrenal incidentalomas

PURPOSE

We aimed to develop a predictive model able to stratify patients with non-functioning adrenal incidentalomas (AIs), according to their risk for developing autonomous cortisol secretion (ACS) during follow-up.

METHODS

This was a retrospective study of patients with non-functioning AIs consecutively evaluated at a single institution between 2013 and 2019 in whom hormonal follow-up information was available for at least 1 year. Clinical, biochemical, and radiological features were used to build a multivariate Cox regression model using the estimation of all possible equations.

RESULTS

We included 331 patients with non-functioning AIs. ACS (post-dexamethasone suppression test (DST) serum cortisol > 1.8 µg/dL) developed in 73 patients during a median follow-up time of 35.7 months [range 12.8-165.4]. The best predictive model for ACS development during follow-up combined age, post-DST serum cortisol, and bilaterality at presentation and showed good diagnostic accuracy (AUC-ROC 0.70 [95% CI 0.65-0.75]). The lowest risk for ACS development was found among patients < 50 years old with cortisol post-DST values < 0.45 µg/dL and with unilateral tumors (risk 2.42%). Baseline post-DST serum cortisol levels at diagnosis were the most important factor for the development of ACS during follow-up (hazard ratio 3.56 for each µg/dL, p < 0.001). The rate of ACS development was associated with post-DST cortisol levels, being 19.2, 32.3, and 68.1 cases/10,000 person-years for patients with baseline post-DST cortisol < 0.9 µg/dL, 0.9-1.3 µg/dL, and > 1.3 µg/dL, respectively.

CONCLUSION

After ruling out malignancy, follow-up visits for patients < 50 years old with unilateral non-functioning AIs and post-DST serum cortisol < 0.45 µg/dL are considered unnecessary given the low risk of developing ACS during follow-up.

Characterisation of the urinary steroid profile of patients with nonfunctioning adrenal incidentalomas: A matched controlled cross-sectional study

AIM

To identify alterations in steroid metabolism in patients with nonfunctioning adrenal incidentalomas (NFAIs) through the analysis of their urinary steroid profile (USP).

METHODS

Cross-sectional study with one study group (NFAIs, cortisol post dexamethasone suppression test [DST] ≤ 1.8 µg/dl [49.7 nmol/L]) and 2 control groups: patients with autonomous cortisol secretion (ACS group, cortisol post-DST > 1.8 µg/dl (49.7 nmol/L) and patients without adrenal tumours (healthy-adrenal group). Twenty-four-hour urine collections for USP measurement (total and free fraction of 51 24 h-urine specimens) were obtained from 73 participants (24 with NFAIs, 24 without AIs, and 25 with ACS). USP was determined by gas chromatography coupled to mass spectrometry. Patients of the three groups were matched according to sex, age (±5 years-old) and body mass index (±5 kg/m² ).

RESULTS

Compared to healthy-adrenal controls, patients with NFAIs had a lower excretion of androgen metabolites (230.5 ± 190.12 vs. 388.7 ± 328.58 µg/24 h, p = .046) and a higher excretion of urinary free cortisol (UFC) (54.3 ± 66.07 vs. 25.4 ± 11.16 µg/24 h, p = .038). UFC was above the reference range in 20.8% of patients in the NFAI, compared to 0% in the healthy-adrenal group (p = .018). Patients with ACS had a higher prevalence of hypertension, dyslipidemia, and diabetes than patients with NFAIs or the control group. A lower excretion of androgen metabolites (218.4 ± 204.24 vs. 231 ± 190 µg/24 h, p = .041) and a nonsignificant higher excretion of glucocorticoid metabolites (2129.6 ± 1195.96 vs. 1550.8 ± 810.03 µg/24 h, p = .180) was found in patients with ACS compared to patients with NFAIs.

CONCLUSION

NFAIs seem to secrete a subtle, yet clinically relevant, excess of glucocorticoids. Future studies are needed to confirm our findings; and to identify metabolic alterations associated with an increased cardiometabolic risk.

Evaluation of Body Composition in Patients With and Without Adrenal Tumors and Without Overt Hypersecretory Syndromes

OBJECTIVE

To compare body composition between patients with autonomous cortisol secretion (ACS), those with nonfunctioning adrenal incidentalomas (NFAIs), and control subjects without adrenal tumors.

METHODS

A cross-sectional study was performed, incluidng the following 3 groups: patients with ACS (cortisol post-dexamethasone suppression test [DST] >1.8 μg/dL), NFAIs (cortisol post-DST ≤ 1.8 μg/dL), and patients without adrenal tumors (control group). Patients of the 3 groups were matched according to age (±5 years), sex, and body mass index (±5 kg/m²). Body composition was evaluated by bioelectrical impedance and abdominal computed tomography (CT) and urinary steroid profile by gas chromatography mass spectrometry.

RESULTS

This study enrolled 25 patients with ACS, 24 with NFAIs, and 24 control subjects. Based on CT images, a weak positive correlation between the serum cortisol level post-DST and subcutaneous fat area (r = 0.3, P =.048) was found. As assessed by bioelectrical impedance, lean mass and bone mass were positively correlated with the excretion of total androgens (r = 0.56, P <.001; and r = 0.58, P <.001, respectively); visceral mass was positively correlated with the excretion of glucocorticoid metabolites and total glucocorticoids (r = 0.28, P =.031; and r = 0.42, P =.001, respectively). Based on CT imaging evaluation, a positive correlation was observed between lean mass and androgen metabolites (r = 0.30, P =.036) and between visceral fat area, total fat area, and visceral/total fat area ratio and the excretion of glucocorticoid metabolites (r = 0.34, P =.014; r = 0.29, P =.042; and r = 0.31, P =.170, respectively).

CONCLUSION

The urinary steroid profile observed in adrenal tumors, comprising a low excretion of androgen metabolites and high excretion of glucocorticoid metabolites, is associated with a lower lean mass and bone mass and higher level of visceral mass in patients with adrenal tumors.

Clinical value of molecular markers as diagnostic and prognostic tools to guide treatment of thyroid cancer

OBJECTIVE

Advances in our understanding of the molecular biology of thyroid tumours is being rapidly translated into their clinical management. This review summarizes the current use of molecular testing in thyroid tumours, focusing on their usefulness as diagnostic and prognostic tools to guide treatment with consideration of present limitations.

DESIGN

Considerations about molecular testing applications for the diagnosis and treatment of thyroid tumours are divided into four sections/roles: (1) evaluating cytologically indeterminate thyroid nodules; (2) guiding extent of surgery in indeterminate thyroid nodules; (3) completing histological characterization of thyroid tumours and (4) identifying actionable mutations in advanced progressive thyroid cancers.

RESULTS

Genomic testing can improve the presurgical malignancy risk assessment in indeterminate thyroid nodules. However, a prior in-depth analysis of institutional quality and outcomes of sonographical, cytological and histological characterization of thyroid tumours is necessary. Presently, it remains uncertain whether knowing the molecular profile of a cytologically indeterminate thyroid nodule might be advantageous to modify the extent of initial surgery. Molecular characterization of thyroid tumours can be a valuable adjunct to morphological diagnosis in some challenging cases, such as in low-risk follicular cell-derived neoplasms, or rare tumours. Finally, as selective kinase inhibitors are available, molecular testing in locally advanced/metastatic progressive thyroid cancers should also be integrated into the institutional clinical management pathway to improve outcomes and limit toxicity.

CONCLUSIONS

Molecular testing needs to be implemented into the local evidence-based clinical management thyroid nodule/cancer pathways to improve its diagnostic and prognostic value and to optimize cost-effectiveness.

A Proposal for Nomenclature Revision of Non-functioning Adrenal Incidentalomas as Adrenal Lesions of Undetermined Secretion of Adrenal Steroids (ALUSAS)

In this commentary we propose a change of the nomenclature of non-functioning adrenal incidentalomas (NFAI) to adrenal lesions of undetermined secretion of adrenal steroids (ALUSAS) since there are mounting evidence suggesting that a substantial proportion of so-called NFAIs do actually secrete steroids in excess. In fact, it is known that some NFAIs develop ACS over time. In the commentary we justify the change of term by summarizing the evidence that shows that NFAIs present a higher cardiometabolic risk than the general population, and the metabolomics studies in which an increase in cortisol metabolites is observed in patients with NFAI.

Predictive model of pheochromocytoma based on the imaging features of the adrenal tumours

The purpose of our study was to develop a predictive model to rule out pheochromocytoma among adrenal tumours, based on unenhanced computed tomography (CT) and/or magnetic resonance imaging (MRI) features. We performed a retrospective multicentre study of 1131 patients presenting with adrenal lesions including 163 subjects with histological confirmation of pheochromocytoma (PHEO), and 968 patients showing no clinical suspicion of pheochromocytoma in whom plasma and/or urinary metanephrines and/or catecholamines were within reference ranges (non-PHEO). We found that tumour size was significantly larger in PHEO than non-PHEO lesions (44.3 ± 33.2 versus 20.6 ± 9.2 mm respectively; P < 0.001). Mean unenhanced CT attenuation was higher in PHEO (52.4 ± 43.1 versus 4.7 ± 17.9HU; P < 0.001). High lipid content in CT was more frequent among non-PHEO (83.6% versus 3.8% respectively; P < 0.001); and this feature alone had 83.6% sensitivity and 96.2% specificity to rule out pheochromocytoma with an area under the receiver operating characteristics curve (AUC-ROC) of 0.899. The combination of high lipid content and tumour size improved the diagnostic accuracy (AUC-ROC 0.961, sensitivity 88.1% and specificity 92.3%). The probability of having a pheochromocytoma was 0.1% for adrenal lesions smaller than 20 mm showing high lipid content in CT. Ninety percent of non-PHEO presented loss of signal in the “out of phase” MRI sequence compared to 39.0% of PHEO (P < 0.001), but the specificity of this feature for the diagnosis of non-PHEO lesions low. In conclusion, our study suggests that sparing biochemical screening for pheochromocytoma might be reasonable in patients with adrenal lesions smaller than 20 mm showing high lipid content in the CT scan, if there are no typical signs and symptoms of pheochromocytoma.

Accuracy of the dexamethasone suppression test for the prediction of autonomous cortisol secretion-related comorbidities in adrenal incidentalomas

PURPOSE

The aim of this study was to evaluate the diagnostic accuracy of the 1 mg dexamethasone suppression test (DST) for the prediction of autonomous cortisol secretion (ACS)-related comorbidities in patients with adrenal incidentalomas (AIs).

METHODS

This was a retrospective multicenter study. We recruited patients with AI/s ≥ 1 cm, excluding those who, during the study, were found during the extension study of an extra-adrenal cancer, with a known diagnosis of hereditary syndromes characterized by adrenal tumors, those presenting with overt hormonal excess syndromes, and those in whom the DST results were missing.

RESULTS

A total of 823 patients met the inclusion criteria. Based on the 1.8, 3.0, and 5.0 µg/dl post-DST cortisol thresholds, the prevalence of ACS was 33.5%, 13.7%, and 5.6%, respectively. The prevalence of hypertension (OR = 1.8, 95% CI = 1.3-2.4), diabetes (OR = 1.6, 95% CI = 1.2-2.2), and dyslipidemia (OR = 1.4, 95% CI = 1.0-1.9) was higher with cortisol post-DST ≥ 1.8 µg/dl; the prevalence of hypertension (OR = 2.1, 95% CI = 1.4-3.3) and diabetes (OR = 1.7, 95% CI = 1.1-2.6) was higher with values ≥ 3.0 µg/dl; and the prevalence of hypertension (OR = 2.0, 95% CI = 1.0-3.7) was higher with levels ≥ 5.0 µg/dl. However, the diagnostic accuracy of the DST for the prediction of cardiometabolic comorbidities in patients with AIs was poor, with areas under the ROC curve < 0.61.

CONCLUSIONS

The DST is a poor predictor of cardiometabolic comorbidities in patients with AIs regardless of the cortisol cut-off values applied. This finding suggests that the diagnosis of ACS should not be based solely on the results of the DST. Other clinical, metabolic, or imaging markers showing a better performance for the prediction of the development and progression of cardiometabolic comorbidities in AIs need to be identified.

Maximum adenoma diameter, regardless of uni- or bilaterality, is a risk factor for autonomous cortisol secretion in adrenal incidentalomas

PURPOSE

To evaluate differences between patients with unilateral and bilateral adrenal incidentalomas (AIs) in the prevalence of autonomous cortisol secretion (ACS) and related comorbidities.

METHODS

In this multicentre retrospective study, AIs ≥ 1 cm without overt hormonal excess were included in the study. ACS was defined by a post-dexamethasone suppression test (DST) serum cortisol ≥ 5.0 µg/dl, in the absence of signs of hypercortisolism. For the association of ACS with the prevalence of comorbidities, post-DST serum cortisol was also analysed as a continuous variable.

RESULTS

Inclusion criteria were met by 823 patients, 66.3% had unilateral and 33.7% bilateral AIs. ACS was demonstrated in 5.7% of patients. No differences in the prevalence of ACS and related comorbidities were found between bilateral and unilateral AIs (P > 0.05). However, we found that tumour size was a good predictor of ACS (OR = 1.1 for each mm, P < 0.001), and the cut-off of 25 mm presented a good diagnostic accuracy to predict ACS (sensitivity of 69.4%, specificity of 74.1%). During a median follow-up time of 31.2 (IQR = 14.4-56.5) months, the risk of developing dyslipidaemia was increased in bilateral compared with unilateral AIs (HR = 1.8, 95% CI = 1.1-3.0 but, this association depended on the tumour size observed at the end of follow-up (HR adjusted by last visit-tumour size = 0.9, 95% CI = 0.1-16.2).

CONCLUSIONS

Tumour size, not bilaterality, is associated with a higher prevalence of ACS. During follow-up, neither tumour size nor bilaterality were associated with the development of new comorbidities, yet a larger tumour size after follow-up explained the association of bilateral AIs with the risk of dyslipidaemia.

Outcomes of repeat fineneedle aspiration biopsy for AUS/FLUS thyroid nodules

OBJECTIVE

To determine the proportion of aspirates reclassified into each Bethesda category and to assess the rates of malignancy in each of them on repeat fine-needle aspiration biopsy (RFNA) following an AUS/FLUS diagnosis.

DESIGN

Systematic review and meta-analysis.

METHODS

On February 2019, Pubmed/MEDLINE, EMBASE, WoS, and the Cochrane Library were searched for articles published from January 1, 2007. All studies published in English describing RFNA outcomes in AUS/FLUS nodules were included. PRISMA and MOOSE guidelines were followed. Five investigators independently assessed the eligibility of the studies. Two investigators extracted summary data and assessed the risk of bias. Data were pooled using a random-effects model. The rate of malignancy was calculated on resected nodules only (upper limit of true value); and considering all unresected nodules were benign (lower limit of true value). The protocol was registered in PROSPERO (CRD42019123114).

RESULTS

Of 2937 retrieved studies, 27 were eligible. The meta-analysis was conducted on summary data of 3932 AUS/FLUS thyroid nodules with RFNA. RFNA cytology would reclassify into categories I through VI of Bethesda: 4% (3%, 5%), 48% (43%, 54%), 26% (20%, 32%), 4% (3%, 6%), 5% (3%, 6%), and 2% (1%, 2%) of AUS/FLUS nodules. Malignancy rates of resected nodules were 24% (9%, 38%), 4% (1%, 7%), 40% (28%, 52%), 37% (27%, 47%), 79% (69%, 90%), and 99% (95%, 100%) for categories I through VI of Bethesda. There was high heterogeneity in these data.

CONCLUSIONS

RFNA reclassified two-thirds of the AUS/FLUS specimens into a more definitive cytological category, with a benign call rate of nearly 50% and a negative predictive value greater than 96%.

Molecular Determinants of Thyroid Nodules with Indeterminate Cytology and RAS Mutations

Background:RAS gene family mutations are the most prevalent in thyroid nodules with indeterminate cytology and are present in a wide spectrum of histological diagnoses. We evaluated differentially expressed genes and signaling pathways across the histological/clinical spectrum of RAS-mutant nodules to determine key molecular determinants associated with a high risk of malignancy. Methods: Sixty-one thyroid nodules with RAS mutations were identified. Based on the histological diagnosis and biological behavior, the nodules were grouped into five categories indicating their degree of malignancy: non-neoplastic appearance, benign neoplasm, indeterminate malignant potential, low-risk cancer, or high-risk cancer. Gene expression profiles of these nodules were determined using the NanoString PanCancer Pathways and IO 360 Panels, and Angiopoietin-2 level was determined by immunohistochemical staining. Results: The analysis of differentially expressed genes using the five categories as supervising parameters unearthed a significant correlation between the degree of malignancy and genes involved in cell cycle and apoptosis (BAX, CCNE2, CDKN2A, CDKN2B, CHEK1, E2F1, GSK3B, NFKB1, and PRKAR2A), PI3K pathway (CCNE2, CSF3, GSKB3, NFKB1, PPP2R2C, and SGK2), and stromal factors (ANGPT2 and DLL4). The expression of Angiopoietin-2 by immunohistochemistry also showed the same trend of increasing expression from non-neoplastic appearance to high-risk cancer (p < 0.0001). Conclusions: The gene expression analysis of RAS-mutant thyroid nodules suggests increasing upregulation of key oncogenic pathways depending on their degree of malignancy and supports the concept of a stepwise progression. The utility of ANGPT2 expression as a potential diagnostic biomarker warrants further evaluation.

Thyroid Cancer Incidence Trends in the United States: Association with Changes in Professional Guideline Recommendations

Background: Overdiagnosis is the leading factor contributing to the rapid increase in thyroid cancer incidence of the last decades. During this period, however, thyroid cancer incidence has not been increasing at a constant pace. We hypothesized that changes in the slope of the incidence trends curve, called joinpoints, could be associated with changes in clinical practice guideline recommendations. Methods: Data were obtained from the initial nine registries of the Surveillance, Epidemiology, and End Results (SEER) Program. Thyroid cancer incidence was analyzed from 1975 to 2016. Joinpoints in thyroid cancer incidence trends and clinical variables were correlated with significant changes in clinical practice recommendations. Results: Incidence rate trends of medullary and anaplastic thyroid cancer were constant during the study period. Among papillary thyroid cancers (PTCs), three main joinpoints were identified, mainly driven by changes in incidence trends of smaller cancers. First, acceleration followed by two deceleration periods in thyroid cancer incidence coincident in time with the release of American Thyroid Association guidelines in 1996, 2009, and 2015. In 1996, the use of thyroid ultrasound and fine needle aspiration biopsy for the evaluation of thyroid nodules was described; and in 2009 and 2015, higher size thresholds for the biopsy of thyroid nodules were set. For the follicular variant of PTC, a joinpoint was observed around 1988, when the histological diagnosis of this entity was revised in the World Health Organization classification; and another one in 2015 coinciding with the proposal to remove the term carcinoma from noninvasive follicular-pattern tumors with papillary-like nuclear features which contributed to drive down the overall thyroid cancer incidence. Follicular thyroid cancer incidence was affected as well by changes in the guidelines, but to a lesser extent, and it was fairly stable during the study period. Conclusions: This study suggests that thyroid cancer incidence trends have been shaped, in large part, but not completely, by changes in professional guideline recommendations.

Ultrasound characterization for thyroid nodules with indeterminate cytology: inter-observer agreement and impact of combining pattern-based and scoring-based classifications in risk stratification

BACKGROUND

The American Thyroid Association (ATA) sonographic patterns stratify the risk of malignancy of cytologically indeterminate thyroid nodules (ITNs). This study aimed to (1) assess inter-observer agreement for sonographic features and patterns; (2) identify potential sources of disagreement; and (3) evaluate whether the number of suspicious features risk-stratifies non-ATA and high-suspicion patterns.

METHODS

Three observers independently reviewed the ultrasound images of 463 ITNs with histological follow-up consecutively evaluated between October 2008 and June 2015 at an academic cancer center. Each observer evaluated individual sonographic features. ATA sonographic patterns were derived from the interpretation of sonographic features. Nodules not fitting into any of the proposed patterns were clustered into a non-ATA pattern.

RESULTS

The inter-observer agreement for ATA sonographic patterns and echogenicity was fair, moderate for margins, good for composition and echogenic foci, and very good for extrathyroidal extension and lymph node metastasis. The interpretation of each sonographic feature was significantly different between observers, and there was complete disagreement in at least one of the features in 104 (22%) nodules. A total of 169 nodules (37%) were classified into the non-ATA pattern. The number of suspicious features allowed risk stratifying nodules with non-ATA and high-suspicion sonographic patterns. Most Non-invasive Follicular Thyroid Neoplasms with Papillary-like Nuclear Features had 0-1 suspicious features and none had >2.

CONCLUSIONS

Echogenicity interpretation was the greatest source of disagreement. The number of suspicious features risk-stratifies ITNs with non-ATA or high-suspicion patterns. Future studies attempting to objectivize the interpretation of echogenicity and heterogeneity are needed.

Association of Tumor Size With Histologic and Clinical Outcomes Among Patients With Cytologically Indeterminate Thyroid Nodules

Importance

Tens of thousands of unnecessary operations are performed each year for diagnostic purposes among patients with cytologically indeterminate thyroid nodules. Whereas a diagnostic lobectomy is recommended for most patients with solitary indeterminate thyroid nodules, a total thyroidectomy is preferred for nodules larger than 4 cm.

Objective

To determine whether histologic or clinical outcomes of indeterminate thyroid nodules 4 cm or larger are worse than those for nodules smaller than 4 cm, thus justifying a more aggressive initial surgical approach.

Design, Setting, and Participants

In this retrospective cohort study, 652 indeterminate thyroid nodules (546 nodules <4 cm and 106 nodules ≥4 cm) with surgical follow-up were consecutively evaluated at an academic cancer center from October 1, 2008, through April 30, 2016.

Exposure

Tumor size.

Main Outcomes and Measures

Differences in cancer rates, rates of invasive features, cancer aggressiveness, and response to therapy between indeterminate thyroid nodules smaller than 4 cm and 4 cm or larger.

Results

A total of 652 indeterminate thyroid nodules (546 nodules <4 cm and 106 nodules ≥4 cm) from 589 patients (mean [SD] age, 53.1 [13.8] years; 453 [76.9%] female) were studied. No differences were found in the baseline characteristics of patients or nodules between the 2 size groups. Tumor size was not associated with the cancer rate as a categorical (140 of 546 [25.6%] for nodules <4 cm and 33 of 106 [31.1%] for nodules ≥4 cm; effect size, 0.05; 95% CI, 0.002-0.12) or continuous (odds ratio [OR], 1.03; 95% CI, 0.92-1.15) variable. No association was found between nodule size and prevalence of extrathyroidal extension, positive margins, lymphovascular invasion, lymph node metastasis, or distant metastasis. Most malignant tumors were low risk in both size groups (70% in the nodules <4 cm and 72% in the nodules ≥4 cm), and tumor size was not associated with tumor aggressiveness as a categorical (effect size, 0.10; 95% CI, 0.03-0.31) or continuous variable (OR for intermediate-risk cancer, 0.91; 95% CI, 0.72-1.14; OR for high-risk cancer, 1.43; 95% CI, 0.96-2.15). At the last follow-up visit, 88 of 105 patients (83.8%) with malignant tumors in the smaller than 4 cm group and 21 of 25 (84.0%) in the 4 cm or greater group had no evidence of disease, and tumor size was not associated with response to therapy (effect size, 0.13; 95% CI, 0.07-0.33).

Conclusions and Relevance

Most indeterminate thyroid nodules are benign or low-risk malignant tumors regardless of tumor size. In the absence of other indications for total thyroidectomy, this study suggests that a thyroid lobectomy is sufficient initial treatment for most solitary cytologically indeterminate thyroid nodules independent of the tumor size.

Comparison of Postmarketing Findings vs the Initial Clinical Validation Findings of a Thyroid Nodule Gene Expression Classifier: A Systematic Review and Meta-analysis

Importance

In the United States, the most used molecular test for the evaluation of cytologically indeterminate thyroid nodules is the Afirma gene expression classifier (GEC).

Objective

To evaluate the GEC's diagnostic performance through a novel approach to assess whether the findings of the initial validation study are consistent with the results of postmarketing studies.

Data Sources

PubMed was systematically searched from inception through October 26, 2017, using the terms gene expression classifier or Afirma or GEC and thyroid.

Study Selection

Studies included were those in which the GEC diagnostic performance could be calculated on consecutively resected cytologically indeterminate thyroid nodules.

Data Extraction and Synthesis

Two observers independently assessed study eligibility and risk of bias using the quality assessment tool for observational cohort and cross-sectional studies of the National Heart, Lung, and Blood Institute. Summary data were extracted by a reviewer and reviewed independently by another. Study authors were contacted if missing data were needed. Data were pooled using a random-effects model. PRISMA and MOOSE guidelines were followed.

Main Outcomes and Measures

Evaluation of the linear correlation between the benign call rate (BCR) and the positive predictive value (PPV).

Results

Of the 137 retrieved titles, 19 (13.9%) were included, comprising a total of 2568 thyroid nodules. Based on a simulation using the sensitivity and specificity reported in the initial validation study, the observed BCR and PPV values in postmarketing studies would have to be explained by different underlying prevalence rates of cancer (15% vs 30%), which is an impossible event. Furthermore, the overall correlation between BCR and PPV for independent studies fell outside the PPV 95% CI of the initial validation study (95% CI, 0.17-0.32) at the BCR of pooled independent studies (0.45) and was just at the limit of the BCR 95% CI of the initial validation study (95% CI, 0.32-0.45) at the PPV of pooled independent studies (0.45). The diagnostic performance was statistically significantly better for atypia or follicular lesions of undetermined significance (diagnostic odds ratio [DOR], 5.67; 95% CI, 4.23-7.60) compared with follicular neoplasms (DOR, 2.24; 95% CI, 1.45-3.47).

Conclusions and Relevance

The findings suggest that the initial validation study cohort was not representative of the populations in whom the GEC has been used, calling into question its reported diagnostic performance, including its negative predictive value.

Interinstitutional variation in predictive value of the ThyroSeq v2 genomic classifier for cytologically indeterminate thyroid nodules

BACKGROUND

The ThyroSeq v2 next-generation sequencing assay estimates the probability of malignancy in indeterminate thyroid nodules. Its diagnostic accuracy in different practice settings and patient populations is not well understood.

METHODS

We analyzed 273 Bethesda III/IV indeterminate thyroid nodules evaluated with ThyroSeq at 4 institutions: 2 comprehensive cancer centers (n = 98 and 102), a multicenter health care system (n = 60), and an academic medical center (n = 13). The positive and negative predictive values of ThyroSeq and distribution of final pathologic diagnoses were analyzed and compared with values predicted by Bayes theorem.

RESULTS

Across 4 institutions, the positive predictive value was 35% (22%-43%) and negative predictive value was 93% (88%-100%). Predictive values correlated closely with Bayes theorem estimates (r² = 0.84), although positive predictive values were lower than expected. RAS mutations were the most common molecular alteration. Among 84 RAS-mutated nodules, malignancy risk was variable (25%, range 10%-37%) and distribution of benign diagnoses differed across institutions (adenoma/hyperplasia 12%-85%, noninvasive follicular thyroid neoplasm with papillary-like nuclear features 5%-46%).

CONCLUSION

In a multi-institutional analysis, ThyroSeq positive predictive values were variable and lower than expected. This is attributable to differences in the prevalence of malignancy and variability in pathologist interpretations of noninvasive tumors. It is important that clinicians understand ThyroSeq performance in their practice setting when evaluating these results.

Thyroid Nodules with Indeterminate Cytology: Utility of the American Thyroid Association Sonographic Patterns for Cancer Risk Stratification

BACKGROUND

The 2015 American Thyroid Association (ATA) guidelines recommend using a classification based on sonographic patterns to set the size threshold for biopsies. Each pattern is associated with a distinct estimated rate of malignancy that it was hypothesized should stratify the risk of malignancy of cytologically indeterminate thyroid nodules (ITNs).

METHODS

Ultrasound images of 463 ITNs (38% atypia/follicular lesions of undetermined significance; 62% follicular neoplasms) with histological follow-up consecutively evaluated between October 2008 and June 2015 at the authors' academic cancer center were independently evaluated by three observers and classified into one of the five sonographic patterns proposed by the ATA. Nodules with sonographic patterns not defined in the classification were grouped into a non-ATA pattern category. Differences in clinical and histological findings between the sonographic patterns were assessed. The prevalence of malignancy and odds ratio for malignancy were calculated for each sonographic pattern (low and intermediate patterns were collapsed for the analysis).

RESULTS

The distribution of size and cytological diagnosis was significantly different between sonographic patterns (p < 0.001). The overall rate of malignancy was 27%. The rate of malignancy for the very low, low/intermediate, high, and non-ATA patterns were 0%, 19%, 56%, and 36%, respectively, and were all significantly different. Compared to the low/intermediate suspicion patterns, the odds ratios for malignancy were 2.35 for the non-ATA and 5.18 for the high suspicion patterns (p < 0.001). The odds ratio of the non-ATA pattern was 0.45 over the high suspicion pattern (p = 0.04). Results were similar in both cytological categories and for each observer separately. Sonographic patterns were associated with distinct histopathological profiles (p < 0.001).

CONCLUSIONS

ATA sonographic patterns are associated with distinct clinical features and pathological outcomes, and effectively stratify the cancer risk in ITNs. Thus, the ATA sonographic patterns should be used not only to set the size threshold for biopsy, but also to personalize management after the biopsy.

Evaluation and Management of Indeterminate Thyroid Nodules: The Revolution of Risk Stratification Beyond Cytological Diagnosis

In accordance with National Guidelines, we currently follow a linear approach to the diagnosis of thyroid nodules, with management decision based primarily on a cytological diagnosis following fine-needle aspiration biopsy. However, 25% of these biopsies render an indeterminate cytology, leaving uncertainty regarding appropriate management. Individualizing the risk of malignancy of these nodules could improve their management significantly. We summarize the current evidence on the relevance of clinical information, radiological features, cytological features, and molecular markers tests results and describe how these can be integrated to personalize the management of thyroid nodules with indeterminate cytology. Several factors can be used to stratify the risk of malignancy in thyroid nodules with indeterminate cytology. Male gender, large tumors (>4 cm), suspicious sonographic patterns, and the presence of nuclear atypia on the cytology are all associated with an increased cancer prevalence. The added value of current molecular markers in the risk stratification process needs further study because their performance seems compromised in some clinical settings and remains to be validated in others. Risk stratification is possible in thyroid nodules with indeterminate cytology using data that are often underused by current guidelines. Future guidelines should integrate these factors and personalize the recommended diagnostic and therapeutic approaches accordingly.

Impact of oncogene panel results on surgical management of cytologically indeterminate thyroid nodules

BACKGROUND

The impact of oncogene panel results on the surgical management of indeterminate thyroid nodules (ITNs) is currently unknown.

METHODS

Surgical management of 649 patients consecutively evaluated from October 2008 to April 2016 with a single nodule biopsied and indeterminate cytology (193 evaluated with and 456 without oncogene panels) was assessed and compared. Histological features of 629 consecutively resected ITNs (164 evaluated with and 465 without oncogene panels) were also characterized and compared.

RESULTS

Oncogene panel evaluation was associated with higher rates of total thyroidectomy (45% vs 28%; P = .006), and central lymph node dissection (19% vs 12%; P = .03) without increasing the yield of malignancy or decreasing the rate of completion thyroidectomy. Most malignancies (64%), including 83% of those with driver mutation identified, were low-risk cancers for which a lobectomy could have been sufficient initial treatment.

CONCLUSION

Current oncogene panel results seem insufficient to guide the surgical extent of solitary ITNs.

Cancer Risk Associated with Nuclear Atypia in Cytologically Indeterminate Thyroid Nodules: A Systematic Review and Meta-Analysis

BACKGROUND

Indeterminate categories of thyroid cytopathology (categories B-III and B-IV of the Bethesda system) are integrated by a heterogeneous spectrum of cytological scenarios that are generally clustered for analysis and management recommendations. It has been suggested that aspirates exhibiting nuclear atypia have a higher risk of malignancy. This study aimed to assess whether cytologically indeterminate thyroid nodules with nuclear atypia have a significantly higher cancer risk than those without nuclear atypia.

METHODS

On June 30, 2016, PubMed and EMBASE were searched for articles in English or Spanish using a search strategy developed by an endocrinologist and a librarian. Case reports were excluded, and no date limits were used. The references of all included studies were also screened for relevant missing studies. Studies were included if the prevalences of malignancy of cytologically indeterminate thyroid nodules with histological confirmation with and without nuclear atypia were reported. Studies were excluded if they had: (i) nodules suspicious for malignancy; (ii) nodules with non-indeterminate (B-III or B-IV) cytology on repeated biopsy, if performed; (iii) nodules not consecutively evaluated; or (iv) cohorts overlapping with another larger series. Two investigators independently assessed the eligibility and risk of bias of the studies. PRISMA and MOOSE guidelines were followed. Summary data were extracted from published reports by one investigator and independently reviewed by another. Data were pooled using a random-effects model. Heterogeneity was explored using subgroup analysis and mixed-effect model meta-regression. The odds ratio for malignancy of cytologically indeterminate thyroid nodules with nuclear atypia over cytologically indeterminate thyroid nodules without nuclear atypia was calculated.

RESULTS

Of 2571 retrieved studies, 20 were eligible. The meta-analysis was conducted on summary data of 3532 cytologically indeterminate thyroid nodules: 1162 with and 2370 without nuclear atypia. The odds ratio for malignancy in cytologically indeterminate thyroid nodules with nuclear atypia was 3.63 [confidence interval 3.06-4.35]. There was no evidence of publication bias, and heterogeneity was insignificant (I² < 0.01%, p = 0.40).

CONCLUSIONS

Nuclear atypia is a significant indicator of malignancy in cytologically indeterminate thyroid nodules and needs to be standardized and implemented into clinical practice.

Cancer Risk Stratification of Indeterminate Thyroid Nodules: A Cytological Approach

BACKGROUND

Management recommendations for thyroid nodules rely primarily on the cytological diagnosis. However, 25% of biopsies render an indeterminate cytology for which management decision is more challenging due to heterogeneity of the specimens. This study aimed to stratify the cancer risk through subcategorization of indeterminate cytology.

METHODS

The indeterminate cytological specimens (Bethesda-III or IV) of 518 thyroid nodules consecutively evaluated at our academic cancer center between October 2008 and September 2015, blinded to the histological outcome, were retrospectively reviewed. Cytological specimens were subclassified into four groups: aspirates exhibiting nuclear atypia (n = 158; 31%); architectural atypia (n = 222; 43%); oncocytic features (n = 120; 23%); or other types of atypia (n = 18; 3%). The prevalence of malignancy and odds ratio for malignancy were calculated in 323 nodules with histological confirmation.

RESULTS

The prevalence of malignancy was 26% overall (20% in Bethesda-III and 29% in Bethesda-IV; p = 0.07), and 47%, 12%, 24%, and 25% for aspirates with nuclear atypia, architectural atypia, oncocytic features, or other types of atypia, respectively. The OR of nuclear atypia over architectural atypia was 6.4 (3.4-12.2; p < 0.001), and 2.7 over oncocytic features (1.4-5.1; p = 0.01), whereas the OR of architectural atypia over oncocytic features was 0.4 (0.2-0.9; p = 0.03). Results were similar for Bethesda-III and IV aspirates when analyzed independently. Furthermore, cytological subcategories improved cytology-histology correlation, as they were associated with distinct profiles of histological diagnoses (p < 0.001).

CONCLUSIONS

Cytological subcategories can effectively stratify the risk of malignancy of thyroid nodules with indeterminate cytology and improve cytology-histology correlation.

Evaluation of ThyroSeq v2 performance in thyroid nodules with indeterminate cytology

ThyroSeq v2 claims high positive (PPV) and negative (NPV) predictive values in a wide range of pretest risks of malignancy in indeterminate thyroid nodules (ITNs) (categories B-III and B-IV of the Bethesda system). We evaluated ThyroSeq v2 performance in a cohort of patients with ITNs seen at our Academic Cancer Center from September 2014 to April 2016, in light of the new diagnostic criteria for non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Our study included 182 patients (76% female) with 190 ITNs consecutively tested with ThyroSeq v2. Patient treatment followed our institutional thyroid nodule clinical pathway. Histologies of nodules with follicular variant papillary thyroid carcinoma or NIFTP diagnoses were reviewed, with reviewers blinded to molecular results. ThyroSeq v2 performance was calculated in nodules with histological confirmation. We identified a mutation in 24% (n = 45) of the nodules. Mutations in RAS were the most prevalent (n = 21), but the positive predictive value of this mutation was much lower (31%) than that in prior reports. In 102 resected ITNs, ThyroSeq v2 performance was as follows: sensitivity 70% (46-88), specificity 77% (66-85), PPV 42% (25-61) and NPV 91% (82-97). The performance in B-IV nodules was significantly better than that in B-III nodules (area under the curve 0.84 vs 0.57, respectively; P = 0.03), where it was uninformative. Further studies evaluating ThyroSeq v2 performance are needed, particularly in B-III.

Hypermetabolism on (18)F-Fluorodeoxyglucose Positron Emission Tomography Scan Does Not Influence the Interpretation of Thyroid Cytopathology, and Nodules with a SUVmax <2.5 Are Not at Increased Risk for Malignancy

BACKGROUND

Hypermetabolism of thyroid nodules on (18)F-fluorodeoxyglucose positron emission tomography (PET) is associated with a higher prevalence of malignancy. However, the definition of hypermetabolism and its impact on cytological interpretation are unclear.

METHODS

Medical records of all patients with thyroid nodules who had undergone cytological evaluation at the Moffitt Cancer Center between October 2008 and May 2014 were retrospectively reviewed. Those with a PET scan performed within one year of the cytology composed the study group, and the rest were used as controls. The distribution of the cytological categories, percentage of resection, and prevalence of malignancy among each Bethesda category was compared between both groups.

RESULTS

Fifteen percent (436) of all thyroid nodules with cytological evaluation were in the study group. Maximum standardized uptake values (SUVmax) were directly associated with the probability of having a malignant or a follicular neoplasm cytological diagnosis; and inversely associated with the probability of having a benign cytological diagnosis. However, the prevalence of cancer within each Bethesda category was not associated with SUVmax values. It was found that the prevalence of malignant cytology increased to >5% with SUVmax values ≥2.5. SUVmax values were significantly higher in malignant than in benign nodules on histology (mean values 10.8 vs. 5) but with significant overlap between both groups for either the whole cohort or nodules with indeterminate cytology only limiting its use for differential diagnosis.

CONCLUSIONS

The prevalence of malignancy in thyroid nodules with a SUVmax <2.5 is similar to the general population, and management should not be modified in those patients. The increased prevalence of malignancy among hypermetabolic thyroid nodules (SUVmax ≥2.5) is well characterized by cytology and does not impact the interpretation of cytological categories. Therefore, SUVmax value does not add relevant information once cytology is available.

New American Thyroid Association Sonographic Patterns for Thyroid Nodules Perform Well in Medullary Thyroid Carcinoma: Institutional Experience, Systematic Review, and Meta-Analysis

BACKGROUND

The 2015 American Thyroid Association (ATA) thyroid nodule guidelines recommend selecting nodules for biopsy based on a sonographic pattern classification. These patterns were developed based on features of differentiated thyroid cancer. This study aimed to evaluate the performance and the inter-observer agreement of this classification system in medullary thyroid carcinoma (MTC).

METHODS

The medical records of all patients with MTC evaluated at the authors' institution between 1998 and 2014 were retrospectively reviewed. Only patients with presurgical thyroid ultrasound available for review were included in the study. Five independent reviewers assessed the stored ultrasound images for composition, echogenicity, margins, presence of calcifications, and extrathyroidal extension for each nodule. The presence of suspicious lymph nodes was also evaluated when presurgical lateral neck ultrasound was available for review. Each nodule was classified according to the ATA sonographic patterns. Inter-observer agreement was calculated for each sonographic feature and for the sonographic patterns. To validate the findings, a systematic review of the literature and meta-analysis on the sonographic features of MTC was conducted.

RESULTS

In this institutional cohort, the inter-observer agreement for individual sonographic features was moderate to good (κ = 0.45-0.71), and for the ATA classification it was good (κ = 0.72). Ninety-seven percent (29/30) of the MTCs were classified in the intermediate or high suspicion patterns. A total of 249 MTCs were included in the meta-analysis. Based on pooled frequencies for solid composition and hypoechogenicity, >95% of MTCs would be classified at least in the intermediate suspicion pattern, warranting the lowest-size threshold for biopsy (≥1 cm).

CONCLUSIONS

The sonographic patterns proposed by the ATA perform well in MTC, and inter-observer agreement is good to very good.

Institutional prevalence of malignancy of indeterminate thyroid cytology is necessary but insufficient to accurately interpret molecular marker tests

OBJECTIVE

Several molecular marker tests are available to refine the diagnosis of thyroid nodules. Knowing the true prevalence of malignancy (PoM) within each cytological category is considered necessary to select the most appropriate test and to interpret results accurately. We describe our institutional PoM among cytological categories and report our experience with molecular markers.

DESIGN

Single-center retrospective study.

METHODS

We calculated the institutional PoM for each category of the Bethesda system (Bethesda) on all thyroid nodules with cytological evaluation from October 2008 to May 2014. We estimated the predictive values for Afirma, miRInform, and ThyroSeq v2, based on published sensitivity and specificity. Finally, we assessed our own experience with miRInform.

RESULTS

The PoMs for Bethesda III and IV categories were 21 and 28%, respectively. ThyroSeq v2 achieves the highest theoretical negative and positive predictive values (NPV and PPV) in Bethesda III (98 and 75%) and Bethesda IV categories (96 and 83%). At our institution, miRInform detected a mutation in 16% of 109 indeterminate nodules tested, all in Bethesda IV specimens. Histology was available in 56 (51%) nodules. The observed sensitivity and specificity in Bethesda IV specimens were 63 and 86%, yielding an NPV and a PPV of 75 and 77%, respectively.

CONCLUSIONS

For our current Bethesda III and IV PoM, the actual performance of miRInform was worse than expected. Theoretically ThyroSeq v2 should have the best performance, but it could be affected in the same way as miRInform, given the similarities between the tests. Assessing the institutional performance of each test is necessary along with PoM individualization.