Application of 13-cis-retinoic acid in patients with 131 I scintigraphically-negative metastases of differentiated thyroid carcinoma

Abstract

Introduction: The loss of iodine uptake by differentiated thyroid carcinoma (DTC) cells is a major therapeutic problem especially in patients with nonsurgical metastatic foci or local recurrence. Using 13-cis-retinoic acid, it was attempted to retain iodine uptake as a result of redifferentiation (influence by retinoic acid receptors present in DTC cells).
Material and methods: Between 1999 and 2005, 13-cis-retinoic acid was used in 11 patients with disseminated PTC and high serum level of thyroglobulin (Tg) before ¹³¹I treatment (2 patients were treated twice - 13 treatment cycles in total). Side effects in skin and mucous membranes were observed in all the patients, however, their intensity did not require termination of the therapy.
Results: Increase of iodine uptake was observed in 5 patients (45%). Decreased Tg concentration was observed in 9 patients. In that group, increased ¹³¹I uptake was observed in 4 patients with distant metastases. All determinations of Tg concentrations were carried out under TSH stimulation.
Conclusions: 13-cis-retinoic acid causes an increase of radioiodine uptake in around half of treated patients, however, the follow-up of these patients indicates that this increase does not result in either full remission or even stabilisation of neoplastic disease. The possibility should be considered to use cis-retinoic acid as an independent therapeutic approach in patients with radioiodine non-avid foci of thyroid carcinoma especially those showing high expression of RARb and RXRg receptors.