Increased aggressiveness of thyroid cancer in patients with Graves' disease.

To evaluate whether coexistence of Graves' disease affects the prognosis of thyroid cancer we examined the clinical and pathological characteristics of 22 differentiated thyroid carcinomas concomitant with hyperthyroidism; 13 were associated with Graves' disease, and 9 with autonomous thyroid nodules. Carcinomas were identified in a consecutive series of 359 hyperthyroid patients (132 with Graves' disease and 227 with autonomous thyroid nodules) who underwent surgery during a 6-yr period. One hundred and thirty-seven thyroid carcinomas were found in the 582 euthyroid patients operated on in the same period. In Graves' patients, carcinomas were more often multifocal (46.1% vs. 0%), locally invasive (61.5% vs. 11.1%), and metastatic to lymph nodes (61.5% vs. 11.1%) or to distant sites (23.0% vs. 0%) than in patients with autonomous thyroid nodules. In addition, carcinomas concomitant with Graves' disease were larger (3.3 +/- 1.8 vs. 1.0 +/- 0.7 cm) than the ones associated with autonomous thyroid nodules and showed a high recurrence rate. In euthyroid patients, aggressiveness of thyroid cancer was intermediate. Serum TSH levels were suppressed in all hyperthyroid patients with thyroid cancer. However, circulating thyroid-stimulating antibodies were present in 12 of 13 cancer patients with Graves' disease, but were absent in patients with autonomous thyroid nodules. Our study suggests, therefore, that TSAb may play a role in determining the high aggressiveness of thyroid cancer in Graves' disease patients and indicates that a vigorous treatment should be pursued in this subgroup of patients.