Long-term follow-up of benign thyroid nodules shows favorable prognosis
After 5 years of follow-up, a majority of asymptomatic, benign thyroid nodules exhibited no significant change in size, or actually decreased in size, and diagnoses of thyroid cancer were rare, according to a study in JAMA (2015; doi:10.1001/jama.2015.0956).
Detection of asymptomatic thyroid nodules has increased, largely from improved detection of small incidentally discovered nodules. Consensus is lacking regarding the optimal follow-up of cytologically proven benign lesions and sonographically nonsuspicious nodules.
Current guidelines recommend serial ultrasound examinations and repeat cytology examination if significant growth in the nodule is observed. However, little is known about the actual frequency and magnitude of nodule growth, and there is no reliable method for identifying patients likely to experience growth. The assumption that growing nodules increase a patient's risk of malignancy has been untested, according to background information in the article.
Sebastiano Filetti, MD, of the Universita di Roma Sapienza in Rome, Italy, and colleagues studied the frequency, magnitude, and factors associated with changes in thyroid nodule size. The study involved 992 patients with 1 to 4 asymptomatic, sonographically or cytologically benign thyroid nodules. Patients were recruited from eight hospital-based thyroid-disease referral centers in Italy between 2006 and 2008. Data collected during the first 5 years of follow-up, through January 2013, were analyzed.
Nodule growth occurred in 153 patients (15.4%). One hundred seventy-four of the 1,567 original nodules (11.1%) increased in size. Nodule growth was associated with presence of multiple nodules. In 184 patients (18.5%), nodules shrank. Thyroid cancer was diagnosed in five original nodules (0.3%), only two of which had grown. New nodules developed in 93 patients (9.3%), with detection of one 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," the authors wrote.
"Only 2 of the 5 diagnoses of cancer in an established nodule were preceded by significant growth of the cancerous nodule. 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."