REDIFFERENTIATION THERAPY WITH RETINOIDS - THERAPEUTIC OPTION FOR ADVANCED FOLLICULAR AND PAPILLARY THYROID-CARCINOMA

During the course of tumor progression the differentiated morphologic and functional characteristics of differentiated thyroid carcinomas (D TC) disappear. This corresponds to more aggressive growth, metastatic spread, and loss of iodine uptake. Experimental data give strong evide nce that differentiated functions of iodine metabolism can be reinduce d by retinoic acids, Results of a study performed in patients with adv anced DTC are presented. Twenty patients with DTC (eight follicular, s even papillary, five oxyphilic) were selected for treatment with retin oic acid 1.5 mg/kg body weight/day over 5 weeks. All patients had adva nced tumor stages with prior operative and radioiodine treatment. Exte nsive tumor invasion, distant metastatic spread, or insufficient or no radioiodine uptake precluded any conventional therapeutic option. The aim was to assess the changes under retinoid treatment. Iodine uptake increased in eight patients (three follicular, three papillary, two o xyphilic), Thyroglobulin (TG) as parameter for tumor mass and differen tiation increased in 12 (63%) patients, decreased in 6 (32%), and did not change in 1 (5%), Retinoids do have an effect on differentiation s tatus of DTC, reinducing iodine uptake in 50% of patients, TG levels d o not always parallel a response in iodine uptake.