Many benign thyroid nodules require little surveillance, study finds

Benign thyroid nodules typically don't grow significantly during follow-up surveillance and very rarely become cancerous, a recent study found.

The prospective, observational study followed 992 Italian patients who initially had 1 to 4 asymptomatic, sonographically or cytologically benign thyroid nodules and received annual thyroid ultrasounds for 5 years. Results were published in the March 3 Journal of the American Medical Association.

The study found nodule growth in 15.4% of the patients (95% CI, 14.3% to 16.5%) and shrinkage in 18.5% (95% CI, 16.4% to 20.9%). Thyroid cancer was diagnosed in only 5 of the original nodules (0.3% [95% CI, 0.0% to 0.6%]), 2 of which had grown. An additional cancer was found at thyroidectomy in a nodule that had not been seen during ultrasound. New nodules developed in 93 patients (9.3% [95% CI, 7.5% to 11.1%]), and a cancer was detected in 1 of them.

The study shows that thyroid cancer is rare among patients with asymptomatic, sonographically or cytologically benign thyroid nodules, the authors said. They noted that most nodules don't grow and that those that do grow don't do so significantly, with a mean 5-year largest diameter increase of 4.9 mm. The study also found that fine-needle aspiration cytology of the nodules was associated with a very low false-negative rate (1.1%).

Based on the results, the study authors suggested that the American Thyroid Association's recommendations on repeat cytology be revised to give more weight to clinical and sonographic findings. Nodules that are smaller than a centimeter, sonographically nonsuspicious, or benign based on initial fine-needle aspiration can be safely managed with a second ultrasound examination 1 year later and reassessment after 5 years, the authors suggested.

The study “demonstrates just how low the risk of detecting a thyroid cancer is during follow-up surveillance,” according to an accompanying editorial. Of the 4 nodules that had been classified as benign based on cytology and were later found to be cancerous, all had suspicious features at the start: 3 were solid and hypoechoic and 1 had microcalcifications. This suggests that nodules without suspicious characteristics likely don't require sonographic surveillance with repeat fine-needle aspiration, the editorialists wrote.