The Journal of clinical endocrinology and metabolism 2017 10 12() doi 10.1210/jc.2017-01832
Thyroid nodule growth was once considered concerning for malignancy, but data showing that benign nodules grow questioned the utility of this paradigm. To date, however, no studies have adequately evaluated if growth rates differ in malignant versus benign nodules.
To sonographically evaluate growth rates in benign and malignant thyroid nodules ≥1cm.
Prospective, cohort study of patients with tissue diagnosis of benign or malignant disease, with repeated ultrasound evaluation six or more months apart.
Growth rate in largest dimension of malignant compared to benign thyroid nodules. Regression models were used to evaluate predictors of growth.
126 malignant nodules met inclusion criteria (≥6 month non-operative follow-up) and were compared to 1,363 benign nodules. Malignant nodules were not found to be uniquely selected or prospectively observed solely for low-risk phenotype. Median US intervals were similar (21.8 months for benign nodules; 20.9 months for malignant nodules). Malignant nodules were more likely to grow >2mm/yr compared to benign nodules, (RR=2.5, 95%CI [1.6-3.1], p<0.001), which remained true after adjustment for clinical factors. The relative risk of a nodule being malignant increased with faster growth rates. Malignant nodules growing >2 mm/yr had greater odds of being more aggressive cancers (Intermediate risk: OR=2.99, 95%CI [1.20,7.47], p=0.03; Higher risk: OR=8.69, 95%CI [1.78,42.34], p=0.02).
Malignant nodules, especially higher risk phenotypes, grow faster than benign nodules. As growth >2mm/yr predicts malignant compared to benign disease, this clinical parameter can contribute to the assessment of thyroid cancer risk.