The Afirma GEC demonstrates a lower than expected rate of benign reports in follicular or Hürthle cell neoplasm and a lower than anticipated malignancy rate within GEC-suspicious nodules. These data suggest that the positive predictive value of the GEC is lower than previously reported and call into question the performance of the test when applied in the context of specialized academic cytopathology.

Although thyroid nodules are common, few are malignant and require surgical treatment. A systematic approach to their evaluation is important to avoid unnecessary surgery. Fine-needle aspiration biopsy has resulted in substantial improvements in diagnostic accuracy, cost reductions, and higher malignancy yield at time of surgery. The preferred approach when repeated fine-needle aspiration biopsy fails to yield an adequate specimen remains a challenge. Management of patients with nodules "suspicious for follicular neoplasm" is difficult, since only 15% to 20% of such lesions have been shown to be malignant. Immunohistochemical markers, such as galectin-3 and human bone marrow endothelial cell (HBME-1), have shown promise in preliminary studies. Routine calcitonin measurement in patients with thyroid nodules has been advocated for early detection of medullary thyroid cancer. However, the low frequency of this cancer, coupled with the high cost associated with case detection, has resulted in a lack of general acceptance of this recommendation.

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Tg-IAs remain the method of choice for Tg quantitation in TgAb- patients. In TgAb+ patients with undetectable Tg by immunometric assay, the Tg-MS will detect Tg in up to 20% additional cases. The Tg-RIA will detect Tg in approximately 35% cases, but a significant proportion of these will be clinical false-positive results. The undetectable Tg-MS seen in approximately 40% of TgAb+ cases in patients with disease need further evaluation.

Thyroid nodules are extremely common and can be detected by sensitive imaging in more than 60% of the general population. They are often identified in patients without symptoms who are undergoing evaluation for other medical complaints. Indiscriminate evaluation of thyroid nodules with thyroid biopsy could cause a harmful epidemic of diagnoses of thyroid cancer, but inadequate selection of thyroid nodules for biopsy can lead to missed diagnoses of clinically relevant thyroid cancer. Recent clinical guidelines advocate a more conservative approach in the evaluation of thyroid nodules based on risk assessment for thyroid cancer, as determined by clinical and ultrasound features to guide the need for biopsy. Moreover, newer evidence suggests that for patients with indeterminate thyroid biopsy results, a combined assessment including the initial ultrasound risk stratification or other ancillary testing (molecular markers, second opinion on thyroid cytology) can further clarify the risk of thyroid cancer and the management strategies. This review summarizes the clinical importance of adequate evaluation of thyroid nodules, focuses on the clinical evidence for diagnostic tests that can clarify the risk of thyroid cancer, and highlights the importance of considering the patient’s values and preferences when deciding on management strategies in the setting of uncertainty about the risk of thyroid cancer.