Follow-up for benign thyroid nodules can be extended

By Megan Brooks

NEW YORK (Reuters Health) - The follow up interval for benign thyroid nodules can be safely extended to five years, according to a prospective natural history study.

After five years, most asymptomatic benign thyroid nodules showed no significant change in size (or decreased in size) and diagnoses of thyroid cancer were rare, the study team reports in JAMA March 3.

"Current guidelines call for fairly close follow-up of thyroid nodules, including those that are benign based on initial fine-needle aspiration biopsy or sonography findings," first author Dr. Sebastiano Filetti noted in email to Reuters Health. "The goal is to promptly detect thyroid cancers that arise during follow-up or those that were missed on the initial assessment."

"Until now, nodule growth was regarded as a possible predictor of malignancy," he continued. "This was not confirmed in our study: if a nodule is cytologically or sonographically benign, it is very likely that it will remain benign during follow-up, even if it grows."

"These nodules can thus be safely managed with more relaxed follow-up schedules than those currently recommended. Our study provides documented evidence that it is safe to increase the follow-up interval to 5 years," he explained.

Dr. Filetti, of the Sapienza University of Rome in Italy, and colleagues followed 992 patients with one to four asymptomatic, sonographically, or cytologically benign thyroid nodules.

Over five years, nodules grew in 153 patients (15.4%) and shrank in 184 patient (18.5%).

Clinicians diagnosed thyroid cancer in only five original nodules (0.3%), only two of which had grown. New nodules developed in 93 patients (9.3%), one being cancer.

"One of the goals of surveillance is the prompt detection and treatment of thyroid cancers that arise during follow-up or have been missed on the initial assessment. In the population we studied, these events were rare," Dr. Filetti and colleagues note in their article.

Only two of the five cancers that arose in an established nodule were preceded by significant nodule growth, they point out. "These data suggest that the American Thyroid Association's recommendation for indication for repeat cytology should be revised. Clinical and sonographic findings should probably play larger roles in the decision-making process."

The ATA did not immediately respond to request for comment made by Reuters Health.

Dr. Anne R. Cappola and Dr. Susan J. Mandel of the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, comment on the findings in a linked editorial. (Dr. Cappola is also an Associate Editor for JAMA).

They say the data "provide reassurance" about the validity of a benign cytology result obtained by ultrasound-guided fine-needle aspiration and confirm a very low false-negative rate.

The data also suggest that routine sonographic surveillance with repeat fine-needle aspiration for growth, as recommended by published guidelines, "is not the most efficient strategy to detect the very small number of missed cancers among previously sampled cytologically benign nodules. The one-size-fits-all approach simply does not work. Instead, surveillance strategies should be individualized based on a nodule's sonographic appearance," they write.

The study also shows that many ultrasound-detected nodules are small (< 1 cm) and not suspicious. "In fact, 54% of nodules followed up were initially classified as benign not through fine-needle aspiration but because they were < 1 cm and lacked suspicious sonographic features. "How reliable is the absence of these features at predicting benign disease? The answer is excellent."

Drs. Cappola and Mandel also point out that 69% of nodules remained stable in size and an increase in size was not a harbinger of malignancy. "Benign nodules grow and (the authors) provide insights about predicting when growth is most likely to occur, e.g., in multinodular glands, larger nodule size, and younger patients," they note.

Summing up, they say, "Thyroid nodules are pervasive, whereas thyroid cancer is not. The findings from (this study) represent an important step in improving the efficiency and mitigating the expense of follow-up for the vast majority of thyroid nodules that are either cytologically or sonographically benign."

The study was funded by research grants from the Umberto Di Mario Foundation, Banca d'ltalia, and the Italian Thyroid Cancer Observatory Foundation. The authors have declared no conflicts of interest.

SOURCE: http://bit.ly/1zUSFBi and http://bit.ly/1Kd7TvF

JAMA 2015.

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