Effect of thyroid gland volume in preoperative detection of suspected malignant thyroid nodules in a multinodular goiter.

HYPOTHESIS The detection of suspected malignant thyroid nodules by ultrasonography is associated with thyroid gland volume and tumor size. DESIGN Prospective clinical trial. SETTING A tertiary referral center. PATIENTS Three hundred sixty-five patients with a multinodular goiter with coexistent dominant nodules. MAIN OUTCOME MEASURES The correlation between thyroid gland volume and tumor size and the detection of suspected malignant thyroid nodules by ultrasonography. The incidence of thyroid carcinoma inside and outside the dominant nodules and thyroid gland volume and tumor size in suspected or unsuspected malignant thyroid nodules by ultrasonography were determined. Receiver operating characteristic analysis was used to identify the cutoffs of the tumor size and thyroid gland volume. RESULTS One hundred thyroid carcinomas were found in 69 (18.9%) patients. Forty-one of these carcinomas were inside the dominant nodule, whereas 59 were outside the dominant nodule. Only 9 of the 59 thyroid carcinomas outside the dominant nodules were suspected of being malignant by ultrasonography. Thyroid gland volume less than 38 mL and tumor size larger than 7 mm had 48-fold (odds ratio, 48; P < .001) and 21.5-fold (odds ratio, 21.5; P < .001) increased rates, respectively, of detecting suspected malignant thyroid nodules by ultrasonography. CONCLUSIONS Thyroid gland volume and tumor size were significantly associated with detection of suspected malignant thyroid nodules by ultrasonography. Small thyroid gland volume was associated with detection of suspected malignant thyroid nodules in multinodular goiters.