RESUMEN
Objective To evaluate the efficacy and safety of 13-cis retinoid acid (13-CRA) and all trans retinoid acid (ATAR) redifferentiation therapy in patients with poorly differentiated thyroid cancer. Methods A single-center, randomized, double-blind, parallel controlled clinical trial was preformed. All patients were randomized into three groups. 78 cases were enrolled in each group. The patients were treated by 13-CRA in A group, by ATRA in B group, and by placebo in control group. The induced effects of retinoid acid (RA) and 131I treatment efficacies were defined as primary outcome of efficacy. Results After RA induction therapy, the effective rates in A, B, and control groups were 59.72%, 52.86% and 7.69%, respectively, with statistically significant difference among 3 groups (P<0.05). Compared with control group, A and B groups revealed significant induced efficacies (P<0.017), but there was no significant difference between A group and B group. After 131I treatment, the effective rates in A, B, and control group were 70.83%, 64.29%, and 28.21% respectively, with statistically significant difference (P<0.05). Compared with control group, the effective rates of 131I treatment in A and B groups were significantly raised (P<0.017), but there was no significant difference between A group and B group. The damage of skins and mucous membranes such as desquamation, dry skin, dry lips, dry eyes, etc occurred mostly in A group. The symptoms of nervous system such as headache, dizziness, etc occurred mostly in B group. Conclusions The induced differentiation of 13-CRA or ATRA is an effective method for the treatment of poorly differentiated thyroid carcinoma.