Thyroid cancer yield in patients with Graves' disease selected for surgery on the basis of cold scintiscan defects.

Previous studies have suggested that thyroid nodules found in patients with Graves' disease (GD) have a higher likelihood of being malignant, and that thyroid cancer behaves more aggressively when associated with GD, although both of these assertions remain controversial. The purpose of this study was to assess the frequency of cold scintiscan (SC) defects in patients with GD, and to determine the prevalence of thyroid cancer in such patients. Our secondary objective was to determine if there are any risk factors for developing cold defects by comparing clinical characteristics of both GD patients with cold SC defects and age and gender-matched GD patients without cold defects. We included in this analysis patients with a confirmed diagnosis of GD for whom SC results and adequate follow-up information were available. Clinic records were available in 772 patients with GD. Of these, 325 patients met eligibility criteria. Cold defects were found in 39 of 325 (12.0%) patients. Among these, 22 (56.4%) were referred for surgery, of whom 6 (1.85% of all GD patients, 15.2% of GD patients with cold nodules, 25% of GD patients with palpable nodules, and 27.3% of those undergoing surgery) had papillary thyroid cancer (PTC) in the location corresponding to the SC defect. In 2 PTC patients, no palpable abnormality corresponded to the cold defect found to contain cancer at surgery. One PTC patient was found to have metastatic disease to bone, and 2 additional PTC patients required multiple therapies with radioiodine. Compared to age and gender-matched control patients with GD and without cold SC defects, there were no differences in radioactive iodine uptake (RAIU), goiter size, duration of disease, degree of elevation in microsomal antibody (MA) titers, or thyroid-stimulating immunoglobulin (TSI). We conclude that thyroid scintigraphy is an important preliminary test in the evaluation of patients with GD, and that the prevalence of thyroid cancer in the location corresponding to a focal cold SC defect provides justification for further diagnostic evaluation or surgical management.

The effect of methimazole on cure rates after radioiodine treatment for Graves' hyperthyroidism: a randomized clinical trial.

Forty-two newly diagnosed patients with Graves' hyperthyroidism were randomly assigned to receive 131I therapy after pretreatment with methimazole (21) or beta-blocker alone (21) and prospectively evaluated, to determine possible effects of methimazole on 131I treatment outcome. After randomization, 8 patients were excluded from the study (5 from pretreatment group and 3 from nonpretreatment group). Radioactive iodine (baseline dose 15 mCi, adjusted for goiter size and/or 131I uptake) was administered after pretreatment with methimazole (30 mg initial dose for at least 2 months and stopped 6 days before treatment) and beta-blocker or pretreatment with beta-blocker alone (atenolol 50-100 mg/d). All but one patient in each group became hypothyroid. A similar length of time was required by both groups to achieve hypothyroidism (112 days, [95% confidence interval [CI] = 28 to 196 days) in the pretreated group and 106 days, [95% CI = 45 to 167 days] in nonpretreated patients). Free thyroxine (T4) normalized 44 +/- 39 days after therapy in the nonpretreated group and 35 +/- 30 days in the pretreated group (p = 0.57) and decreased to subnormal levels 80 +/- 70 days in nonpretreated and 65 +/- 32 days in pretreated patients (p = 0.46). We conclude that pretreating patients with methimazole before radioactive iodine therapy does not interfere with the final outcome. Similar cure rates and time required to achieve hypothyroidism after radioiodine were observed when patients were pretreated with methimazole compared to nonpretreated patients.