Recombinant thyrotropin for detection of recurrent thyroid cancer

Abstract

Detection of recurrent thyroid cancer tumor requires TSH stimulation for radioiodine scanning and thyroglobulin (Tg) measurement. Temporary thyroid hormone withdrawal has previously been used, but causes hypothyroidism and, rarely, tumor progression.

Methods: The alternative of recombinant thyrotropin (rTSH) was assessed in two randomized clinical trials in which patients had 131I and Tg testing twice: first after rTSH, and second after thyroid hormone withdrawal. Test results and quality of life were compared.

Results: In the first trial, among 62 of 127 patients with positive scans, rTSH was equivalent to withdrawal in 41, superior in 3, and inferior in 18 (P < 0.05), suggesting a lesser sensitivity of rTSH scans. In a second trial employing enhanced techniques, among 108 of 220 patients with positive scans, there was no difference in the number of superior rTSH and withdrawal scans. Furthermore, among all patients with withdrawal study evidence of residual thyroid tissue, 74% of all patients with residual thyroid tissue and 100% of patients with tumor metastases had rTSH-stimulated thyroglobulin values above 2 ng/mL. Naturally, patients experienced significantly more symptoms and diminished quality of life when hypothyroid than after rhTSH.

Conclusions: Combined rTSH-stimulated radioiodine and Tg testing is as sensitive as thyroid hormone withdrawal to detect recurrent thyroid cancer, and causes less morbidity.