The incidence of bilateral well-differentiated thyroid cancer found at completion thyroidectomy.

The purpose of this study was to evaluate the surgical outcome of completion thyroidectomy in patients with presumed unilateral well-differentiated thyroid cancer (WDTC). The medical records of all patients having had unilateral thyroid lobectomy for WDTC, who subsequently underwent completion thyroidectomy, were reviewed. From 1980 to 1991, 60 patients with WDTC underwent completion thyroidectomy. Forty-seven patients had presumed unilateral WDTC, with no evidence of residual disease prior to their completion thyroidectomy. Twenty-five (53%) of these patients were found to have residual neoplastic disease in the neck. In 20 (43%) of 47 patients, a focus of cancer was found in the remaining thyroid lobe and in 5 additional patients no cancer was found in the contralateral lobe, however, unsuspected nodal disease was found. The remaining 13 of the 60 patients presented with either regional recurrence (n = 12) or distant metastases (n = 1) at the time of their completion thyroidectomy. All (92%) but 1 of these 13 patients had cancer in the remaining thyroid lobe. Multifocal disease in the primary lobe was associated with bilateral thyroid cancer (p less than 0.01). Complications were infrequent; transient hypocalcemia occurred in 5 (8%) patients, permanent hypoparathyroidism occurred in 1 (1.7%) patient, and transient recurrent laryngeal nerve palsy occurred in 3 (5%) patients. Residual WDTC was found in 37 (62%) of 60 patients undergoing completion thyroidectomy. Multifocal disease in the primary resected lobe was associated with a high incidence of contralateral thyroid cancer. Completion thyroidectomy is a safe procedure and may prevent the development of regional recurrence by eliminating an unsuspected focus of cancer.