Clinical experience with recombinant human thyrotrophin (rhTSH) in the management of patients with differentiated thyroid cancer

The purpose of this work was to gain clinical experience with and to identi fy the optimal conditions for the use of recombinant human TSH(rhTSH, comme rcially available as Thyrogen(R) in the management of patients with differe ntiated thyroid cancer DTC). The study involved 22 patients for a total of 27 administration cycles of r hTSH,for either diagnostic tin 19 instances) and/or therapeutic purposes ti n 8 instances). There were 19 patients with papillary cancer follicular var iant in 4 columnar variant in 1) and 3 patients with follicular cancer (1 H urtle cell variant). All patients had previously undergone total thyroidect omy and 1-5 cycles of I-131-therapy. Thyrogen(R) was administered i.m. acco rding to the suggested protocol: 0.9 mg i.m. on days 1 and 2 radioiodine on day 3. Peak serum TSH levels between 68-237 mu IU/mL were observed after rhTSH adm inistration; these were on average 65% higher, on a patient-by-patient basi s, than peak serum TSH observed after conventional withdrawal of thyroxine treatment in 19 patients, while in 3 patients they were 28% lower, but stil l in the potent stimulation range (86-94 mu IU/mL). There was general agree ment between imaging results obtained under rhTSH stimulation and those obt ained on prior occasions during thyroxine withdrawal, although radioiodine uptake was interpreted as less intense following Thyrogen(R) administration . Of 18 patients undergoing rhTSH administration for diagnostic purposes, 1 1 patients had a negative radioiodine whole-body scan (WBS) and 7 had a pos itive WBS. Three of the WBS-negative patients were shown to be actually aff ected by tumor recurrence, respectively by PET with [F-18]FDG (in 2 cases) and by post-I-131 therapy scan. Serum thyroglobulin (hTg) increased to abno rmal levels following rhTSH stimulation in 3/7 of the WBS-positive patients as well as in 1/11 WBS-negative patients. In 3/7 WBS-positive as well as i n 3/11 WBS-negative patients, serum hTg progressively rose under rhTSH stim ulation, yet still remaining below 3 ng/mL. Post-I-131 therapy scans follow ing Thyrogen(R) administration showed good radioiodine uptake in 7/8 patien ts, the single unsuccessful case being most likely due to expansion of the iodine pool because of recent use of an iodinated contrast medium. The overall results show the feasibility and practical advantages of employ ing rh TSH stimulation in the general clinical setting rather than thyroxin e withdrawal in the management of DTC patients. Caution should be raised on the interpretation of the serum hTg response to such potent but short-live d TSH stimulation.