Michael T. Stang

Impact of Mutational Testing on the Diagnosis and Management of Patients with Cytologically Indeterminate Thyroid Nodules: A Prospective Analysis of 1056 FNA Samples

CONTEXT Thyroid nodules are common in adults, but only a small fraction of them is malignant. Fine-needle aspiration (FNA) cytology provides a definitive diagnosis of benign or malignant disease in many cases, whereas about 25% of nodules are indeterminate, hindering most appropriate management. OBJECTIVE The objective of the investigation was to study the clinical utility of molecular testing of thyroid FNA samples with indeterminate cytology. DESIGN Residual material from 1056 consecutive thyroid FNA samples with indeterminate cytology was used for prospective molecular analysis that included the assessment of cell adequacy by a newly developed PCR assay and testing for a panel of mutations consisted of BRAF V600E, NRAS codon 61, HRAS codon 61, and KRAS codons 12/13 point mutations and RET/PTC1, RET/PTC3, and PAX8/PPARγ rearrangements. RESULTS The collected material was adequate for molecular analysis in 967 samples (92%), which yielded 87 mutations including 19 BRAF, 62 RAS, 1 RET/PTC, and five PAX8/PPARγ. Four hundred seventy-nine patients who contributed 513 samples underwent surgery. In specific categories of indeterminate cytology, i.e. atypia of undetermined significance/follicular lesion of undetermined significance, follicular neoplasm/suspicious for a follicular neoplasm, and suspicious for malignant cells, the detection of any mutation conferred the risk of histologic malignancy of 88, 87, and 95%, respectively. The risk of cancer in mutation-negative nodules was 6, 14, and 28%, respectively. Of 6% of cancers in mutation-negative nodules with atypia of undetermined significance/follicular lesion of undetermined significance cytology, only 2.3% were invasive and 0.5% had extrathyroidal extension. CONCLUSION Molecular analysis for a panel of mutations has significant diagnostic value for all categories of indeterminate cytology and can be helpful for more effective clinical management of these patients.

Optimizing surgical treatment of papillary thyroid carcinoma associated with BRAF mutation.

BACKGROUND To date, a mutation of the BRAF oncogene is the most common genetic alteration found in papillary thyroid carcinoma (PTC) and is associated with extrathyroidal extension, lymph node metastasis, and tumor recurrence. It is not known whether pre-operative identification of BRAF mutations in cytologic specimens should alter surgical management. METHODS From 2006 to 2008, the clinical, cytologic, and pathologic parameters of 106 consecutive surgically treated patients with BRAF-positive PTC were compared with a concurrent cohort of 100 patients with BRAF-negative PTC. RESULTS In all, 99 BRAF-positive PTC patients underwent initial treatment, and 7 BRAF-positive patients had surgical resection of recurrent/persistent PTC. BRAF mutations were identified on preoperative cytologic samples (31 patients) or after thyroidectomy (75 patients). All 31 patients with BRAF-positive fine-needle aspiration (FNA) had PTC at thyroidectomy (specificity 100%). At short-term follow-up, 11/106 BRAF-positive patients have required reoperation for recurrent/persistent disease compared with 3 BRAF-negative patients (P = .04). Preoperative knowledge of BRAF mutation positivity could have productively altered initial PTC surgical management in 24% of patients. CONCLUSION In PTC, BRAF mutations are associated with cervical recurrence and with reoperation. Pre-operative cytologic identification of BRAF mutation has high specificity and may guide the initial extent of thyroidectomy and node dissection.

Cost Impact of Molecular Testing for Indeterminate Thyroid Nodule Fine-Needle Aspiration Biopsies

Introduction: Molecular testing of fine-needle aspiration (FNA) results helps diagnose thyroid cancer, although the additional cost of this adjunct has not been studied. We hypothesized that FNA molecular testing of two indeterminate categories (follicular lesion of undetermined significance and follicular/Hürthle cell neoplasm) can be cost saving. Methods: For a hypothetical group of euthyroid patients with a 1-cm or larger solitary thyroid nodule, a decision-tree model was constructed to compare the estimated costs of initial evaluation according to the current American Thyroid Association guidelines, either with molecular testing (MT) or without [standard of care (StC)]. Model endpoints were either benign FNA results or definitive histological diagnosis. Results: Molecular testing added

A combined molecular-pathologic score improves risk stratification of thyroid papillary microcarcinoma.

104 per patient to the overall cost of nodule evaluation (StC

RAS Mutations in Thyroid FNA Specimens Are Highly Predictive of Predominantly Low-Risk Follicular-Pattern Cancers

578 vs. MT

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682). In this distributed cost model, MT was associated with a decrease in the number of diagnostic lobectomies (9.7% vs. StC 11.6%), whereas initial total thyroidectomy was more frequent (18.2% vs. StC 16.1%). Although MT use added a diagnostic cost of

A Clinical Algorithm for Fine-needle Aspiration Molecular Testing Effectively Guides the Appropriate Extent of Initial Thyroidectomy

5031 to each additional indicated total thyroidectomy (

Recent developments in predicting thyroid malignancy

11,383), the cumulative cost was still less than the comparable cost of performing lobectomy (

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7684) followed by completion thyroidectomy (

Tumor genotype determines phenotype and disease-related outcomes in thyroid cancer: a study of 1510 patients.

11,954) in the StC pathway, when indicated by histological results. In sensitivity analysis, savings were demonstrated if molecular testing cost was less than