Application of Redifferentiation Therapy with Retinoic Acid in Differentiated Thyroid Carcinoma

Objective Assess the changes of iodine metabolism reinduced by RA in differentiated thyroid carcinoma(DTC).Methods Twenty patients were treated orally with RA for at least 1.5 month before radioiodine(RI) therapy.All patients had insufficient or no radioiodine uptake in clinically important metastatic sites before RA therapy.The patients were grouped by comparing RI uptake post-RA with pre-RA treatment.Student's t test was used for statistical analyses of serum thyroglobulin(Tg) levels.Results Twenty patients were treated twenty-five times,44%(11/25) responded to RA application with an increased RI uptake(responder group).Median Tg levels increased from 382～1 000 ng/ml during RA therapy in the responder group,which was higher than the nonresponder group(176.35～616.25 ng/ml).But the difference of serum Tg levels between pre-and post-RA treatment was not significant(P0.05).Conclusion RA does have an effect on differentiation status of DTC,reinducing RI uptake in some patients with RI negative thyroid carcinoma tumor sites.