Overview of molecular biomarkers for enhancing the management of cytologically indeterminate thyroid nodules and thyroid cancer

Evaluation and management of thyroid nodules in children

PURPOSE OF REVIEW

The review is focused on new information about the presentation and management of thyroid nodules in children and adolescents.

RECENT FINDINGS

Palpable thyroid nodules are uncommon in children but many children have nodules detected by radiologic imaging. How to evaluate them, when to suspect thyroid cancer, and how best to follow apparently benign nodules has become an area of great interest. The American Thyroid Association recently published treatment guidelines for children with thyroid nodules and cancers but much has been learned since that publication.

SUMMARY

Personal and family history, ultrasound features, and fine needle aspiration cytology are used to determine the risk of cancer in thyroid nodules, which are then managed according to cancer risk.

A robust biomarker of differential correlations improves the diagnosis of cytologically indeterminate thyroid cancers

The fine-needle aspiration of thyroid nodules and subsequent cytological analysis is unable to determine the diagnosis in 15 to 30% of thyroid cancer cases; patients with indeterminate cytological results undergo diagnostic surgery which is potentially unnecessary. Current gene expression biomarkers based on well-determined cytology are complex and their accuracy is inconsistent across public datasets. In the present study, we identified a robust biomarker using the differences in gene expression values specifically from cytologically indeterminate thyroid tumors and a powerful multivariate search tool coupled with a nearest centroid classifier. The biomarker is based on differences in the expression of the following genes: CCND1, CLDN16, CPE, LRP1B, MAGI3, MAPK6, MATN2, MPPED2, PFKFB2, PTPRE, PYGL, SEMA3D, SERGEF, SLC4A4 and TIMP1. This 15-gene biomarker exhibited superior accuracy independently of the cytology in six datasets, including The Cancer Genome Atlas (TCGA) thyroid dataset. In addition, this biomarker exhibited differences in the correlation coefficients between benign and malignant samples that indicate its discriminatory power, and these 15 genes have been previously related to cancer in the literature. Thus, this 15-gene biomarker provides advantages in clinical practice for the effective diagnosis of thyroid cancer.

Management of Thyroid Nodular Disease: Current Cytopathology Classifications and Genetic Testing

Preoperative diagnosis and operative planning for patients with thyroid nodules has improved over the last decade. The Bethesda criteria for cytopathologic classification of thyroid nodule aspirate has enhanced communication between pathologists and clinicians. Multiple genetic tests, including molecular markers and the Afirma gene expression classifier, have been developed and validated. The tests, along with clinical and radiologic information, are most useful in the setting of indeterminate cytology. The development of an updated diagnostic and treatment algorithm incorporating all available tests will help standardize the management of patients with nodular thyroid disease and reduce variation and inefficiencies in care.

Management Guidelines for Children with Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Previous guidelines for the management of thyroid nodules and cancers were geared toward adults. Compared with thyroid neoplasms in adults, however, those in the pediatric population exhibit differences in pathophysiology, clinical presentation, and long-term outcomes. Furthermore, therapy that may be recommended for an adult may not be appropriate for a child who is at low risk for death but at higher risk for long-term harm from overly aggressive treatment. For these reasons, unique guidelines for children and adolescents with thyroid tumors are needed.

METHODS

A task force commissioned by the American Thyroid Association (ATA) developed a series of clinically relevant questions pertaining to the management of children with thyroid nodules and differentiated thyroid cancer (DTC). Using an extensive literature search, primarily focused on studies that included subjects ≤18 years of age, the task force identified and reviewed relevant articles through April 2014. Recommendations were made based upon scientific evidence and expert opinion and were graded using a modified schema from the United States Preventive Services Task Force.

RESULTS

These inaugural guidelines provide recommendations for the evaluation and management of thyroid nodules in children and adolescents, including the role and interpretation of ultrasound, fine-needle aspiration cytology, and the management of benign nodules. Recommendations for the evaluation, treatment, and follow-up of children and adolescents with DTC are outlined and include preoperative staging, surgical management, postoperative staging, the role of radioactive iodine therapy, and goals for thyrotropin suppression. Management algorithms are proposed and separate recommendations for papillary and follicular thyroid cancers are provided.

CONCLUSIONS

In response to our charge as an independent task force appointed by the ATA, we developed recommendations based on scientific evidence and expert opinion for the management of thyroid nodules and DTC in children and adolescents. In our opinion, these represent the current optimal care for children and adolescents with these conditions.

Role of ancillary testing in thyroid fine needle aspiration: Review and update

Thyroid nodules are common, and ultrasound-guided fine needle aspiration identifies 70-75% as benign, and 4% as malignant. The remainder falls into categories of "indeterminate" with a widely ranging malignancy rate from 10-75%. The diagnosis and clinical management of indeterminate lesions is evolving, and we will review ancillary testing as an aid to diagnosis.

Molecular markers in thyroid cytology: diagnostic and prognostic implications

The discovery of thyroid nodules in the general population has risen markedly with the greater use of ultrasound resulting in increasing use of ultrasound-guided fine needle aspiration (FNA) biopsy. Although FNA can identify the majority of nodules as either benign or malignant, one-third of aspirates demonstrate indeterminate cytologic characteristics. Though most of these nodules will be pathologically benign, thyroid surgery has usually been needed to make an accurate diagnosis, and the extent of surgery needed (lobectomy versus total thyroidectomy) is difficult to predict in advance. New molecular techniques are being investigated and used clinically to improve decision making in patients with thyroid nodules with indeterminate cytology. These molecular markers have the potential to help clinicians decide which patients may be monitored without thyroid surgery, and also the optimal strategy when surgery is felt to be necessary.