Recurrence rate of tumor and the value of diagnostic I-131 whole body scintigraphy and recombinant TSH in low-risk well differentiated thyroid cancer patients who have had I-131 radioablation

Abstract

Objective: The aim of this study was to find out the recurrence rate and to evaluate effectiveness of diagnostic I-131 whole body scintigraphy (WBS) and recombinant human (rh) TSH in low-risk well differentiated thyroid cancer (WDTC) patients who have had I-131 radioablation and have undetectable stimulated serum thyroglobulin (Tg) levels. Material and Methods: Study groups consisted of 149 patients (Group 1) using endogenous TSH stimulation and 50 patients (Group 2) using rhTSH. Mean follow-up period was 12 years for Group 1. Postablative 6th, 18th month, 5th, 10th and 15th year endogenous TSH stimulated diagnostic WBS and serum Tg levels in G1; and 6th month endogenous TSH stimulated and 18th month rhTSH stimulated diagnostic WBS and serum Tg levels in G2 patients were evaluated. Results: The TSH stimulated Tg values were <1 ng/mL after ablation. The recurrence rate of tumor was 1.3%. Serum TSH levels were ≥30 μIU/mL in all patients. There was no significant difference between 6th month endogenous TSH and 18th month rhTSH stimulated Tg levels and diagnostic WBS in G2 patients and the 6th, 18th month, 5th, 10th and 15th year endogenous TSH stimulated diagnostic WBS and Tg levels in G1 Patients. Conclusion: In low-risk WDTC patients who have undergone total thyroidectomy and I-131 radioablation, the recurrence rate of tumor was extremely low. rhTSH was used successfully without hypothyroid state at I-131 WBS and serum Tg measurement. If 6th month WBS was negative and serum Tg level was undetectable, the 18th month, 5th, 10th and 15th years WBSs were also negative in all patients and yielded no additional information that could influence the following therapeutic strategy and therefore may be avoided. In the follow-up of this group of patients, rhTSH stimulated Tg measurement may be considered as an alternative approach. © 2012 by Türkiye Klinikleri.