A clinical study of all-trans-retinoid-induced differentiation therapy of advanced thyroid cancer

Abstract

To evaluate the changes in differentiation markers and therapeutic effects in all-trans-retinoic acid (ATRA)-treated patients with dedifferentiated thyroid cancer. Between September 2001 and July 2004 eleven patients were analysed retrospectively. They had dedifferentiated thyroid cancers (DTC) (four follicular, five papillary, two oxyphilic) and were selected for treatment with ATRA (1.00+/-0.09 mg x kg x d) for 30 or 60 days. All patients had advanced stage tumours with prior operative and radioiodine treatment. Extensive tumour invasion, distant metastatic spread, and insufficient or non-existent uptake of radioiodine precluded conventional therapeutic options. Changes in I uptake, response of target lesions, and serum thyroglobulin (Tg) levels were measured and compared in these patients before and after ATRA therapy. In 11 patients with DTC, iodine uptake was increased in four and there was a partial response (PR) of target lesions in five patients as well as two patients with stable disease. Tg was assessed in eight patients, in whom two responders showed increased radioiodine uptake or no change and decreased Tg level, as well as PR after ATRA-induced differentiation therapy. ATRA has an effect on the differentiation status of DTC and deserves further investigation.