Malignancy Risk Low for Thyroid Nodule Patients

Few patients undergoing asymptomatic thyroid nodule monitoring will go on to develop malignant disease

medwireNews: Thyroid nodule management guidelines should be reviewed, say Italian researchers who found the very low risk of malignancy was not associated with nodule growth.

Over 5 years, just 15% of the 992 asymptomatic patients showed significant nodule growth, defined as a 20% increase on at least two diameters and at least 2 mm growth, while nodules spontaneously shrank in 18.5% of patients.

Just 0.3% of the original nodules became malignant, report Sebastiano Filetti, from Università di Roma Sapienza in Rome, and co-authors in JAMA.

And although the American Thyroid Association recommends repeat cytology on significant nodule growth, the study found that only two of the five malignant tumours were foreshadowed by nodule growth.

New nodules were detected in 9.3% of the group. One malignant tumour was detected among the new nodules and a second incidental cancer was identified on thyroidectomy, increasing the overall malignancy rate to 0.7%.

“The indolent behavior and limited growth observed in our study confirm that nodules that were benign based on initial fine-needle aspiration or subcentimeter and sonographically nonsuspicious can be safely managed with a second ultrasound examination 1 year after the first (early follow-up) and in the absence of changes, reassessment after 5 years (long-term follow-up)”, the researchers conclude.

“This approach should be suitable for 85% of patients, whose risk of disease progression is low”, they say, recommending “closer surveillance” for younger patients and older overweight individuals with multiple or large nodules or both.

Anne Cappola and Susan Mandel, from the University of Pennsylvania in Philadelphia, USA, write in an accompanying editorial that the study findings are an “important step” in improving the efficiency and costs of thyroid nodule follow-up.

In particular, they note that four of the malignancies detected during follow-up of the original nodules were benign on cytology but did not show typical benign characteristics on ultrasound and were considered suspicious.

“[T]hese data suggest that sonographic surveillance for detection of a missed malignancy is not indicated for cytologically benign nodules that lack any of the accepted suspicious sonographic features […]: hypoechogenicity, irregular margins, taller-than-wide shape, intranodular vascularity, and microcalcifications”, they write.

“Instead, only a subset of nodules with a prior benign cytology result, those with 1 of these suspicious features, may require sonographic surveillance with repeat fine needle aspiration for either development of additional suspicious sonographic imaging characteristics or growth, corroborating recent studies.”

References

Durante C, Costante G, Luciasno G, et al. The natural history of benign thyroid nodules. JAMA 2015; 313(9):926-935. doi:10.1001/jama.2015.0956

Cappola AR, Mandel SJ. Improving the long-term management of benign thyroid nodules. JAMA 2015; 313(9):903-904. doi:10.1001/jama.2015.0836

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