Additionally, many of the patients did not undergo surgery, so it is possible that some of these thyroid glands harbored cancer that was undetected. As noted by the authors, some patients with thyroid nodules may have undergone a thyroidectomy after the surveillance of the study was halted.
It is agreed that monitoring of thyroid nodules by history, physical examination and thyroid ultrasound is critical in order to define growth, with growth being suggestive of thyroid cancer. In this circumstance, a repeat thyroid FNA would be indicated. Of course, benign thyroid nodules may also grow, but a thyroid FNA (in conjunction with ultrasound, history and physical examination) should be able, in most circumstances, to distinguish a benign nodule from a malignant nodule.
The American Thyroid Association (ATA) has developed guidelines for the management of thyroid nodules, including the monitoring of FNA benign thyroid nodules.2 The guidelines note:
“It is recommended that all benign thyroid nodules be followed with serial US (ultrasound) examinations 6–18 months after the initial FNA. If nodule size is stable (i.e., no more than a 50% change in volume or <20% increase in at least two nodule dimensions in solid nodules or in the solid portion of mixed cystic–solid nodules, the interval before the next follow-up clinical examination or US may be longer, e.g., every 3–5 years. If there is evidence for nodule growth either by palpation or sonographically (more than a 50% change in volume or a 20% increase in at least two nodule dimensions with a minimal increase of 2 mm in solid nodules or in the solid portion of mixed cystic–solid nodules), the FNA should be repeated, preferably with US guidance.”2
It would seem that the article by Nou et al supports this recommendation, which was made prior to the publication of the article by Nou et al. However, the ATA guidelines do recommend an initial US 6 to 18 months after the initial FNA. Nou et al recommends repeat surveillance at 2 years from the initial evaluation. Prospective, systematic studies are required to answer this question.
The article by Nou et al certainly represents a step forward in our knowledge. Nevertheless, given the caveats noted above, as well as the variability of cytopathologists’ experience worldwide, and the clinical concept that we do not want to have a false negative thyroid FNA for an aggressive thyroid cancer (which is unlikely but still possible), my recommendation at present is to repeat the thyroid sonogram at 6 to 18 months after the initial evaluation and then proceed with less frequent surveillance as recommended by Nou et al1 and the ATA guidelines.
The optimal duration of monitoring for a patient with a thyroid nodule with a benign FNA is unknown, but perhaps it is reasonable to perform clinical, laboratory and radiologic assessment approximately 1 to 2 years, after the initial evaluations and first reevaluation at 6 to 18 months, for 4 to 5 years and less frequently thereafter.
These patients should probably be monitored for life, but relevant studies in this area are lacking to make a definitive recommendation regarding appropriate time intervals.
Kenneth D. Burman, MD, is director of the Endocrine Section at MedStar Washington Hospital Center (MWHC) in Washington, DC.