Clinical significance of residual occult malignancy in thyroid carcinoma.

PURPOSE

Total or near-total thyroidectomy is advocated in reducing the recurrence rate and improving survival in differentiated thyroid carcinoma. However, this potential benefit could be seen in all patient groups or only in the patients who have multifocal disease. We analyzed the clinical significance of occult multifocal disease in patients with completion thyroidectomy.

PATIENTS AND METHODS

Ninety-seven patients in whom the completion thyroidectomy was performed within 6 months were included. The patients were grouped according to whether they have malignancy in the remnant thyroid tissue. The groups were examined and compared according to patients and tumor characteristics. The effect of the presence of residual tumor in remnant thyroid tissue on clinical course, disease-free survival, and overall survival were evaluated as well.

RESULTS

After completion thyroidectomy, 20 (20.6%) of the 97 patients revealed additional cancer focus in the residual tissue. Median follow-up period was 104 months (range, 84-205 months). Only tumor multifocality in the resected lobe after first surgery was predictive of the presence of malignancy in the thyroid remnant (P = .002; relative risk, 4.9; 95% confidence interval, 1.7-14.5). Detection of malignancy in the remnant thyroid tissue did not affect the disease-free survival (P = .39). There were no deaths in patients who underwent reoperative thyroid surgery.

CONCLUSIONS

Only tumor multifocality in the original thyroid lobe was predictive of finding additional cancer in the contralateral lobe. However, clinical significance of occult multifocal disease was not shown.