Preoperative determination of serum thyroglobulin to identify patients with differentiated thyroid cancer who may present recurrence without increased thyroglobulin.

Thyroglobulin is considered a reliable marker of recurrent disease in patients with well-differentiated thyroid carcinoma. However, some patients present recurrence with no increase in serum thyroglobulin. In the attempt to identify patients who might present recurrence with no such sign of the disease, thyroglobulin levels have been determined pre-operatively in 185 consecutive patients scheduled for primary treatment for well-differentiated thyroid carcinoma from June 1997 to May 2002 at the Head and Neck Division of the European Institute of Oncology. In 22 patients (11.9% of total), serum thyroglobulin was undetectable. In none of these 22 cases was thyroglobulin detected during follow-up, either during thyroxin suppressive therapy or during withdrawal for radioiodine scan. One of these low-thyroglobulin patients developed recurrent disease involving cervical lymph nodes, with positive radioiodine scan: thyroglobulin remained undetectable. On the contrary, in the patients with high or normal thyroglobulin presenting recurrence, the recurrence was indicated, in all cases, by increased thyroglobulin levels. From these findings it may be concluded that pre-operative assessment of serum thyroglobulin may identify patients who might present recurrence without increased thyroglobulin, and in whom standard follow-up by monitoring thyroglobulin serum levels is inadequate.