The Efficacy of Retinoic Acid in Patients with Radioiodine-Refractory Thyroid Cancer: A Meta-analysis

Objectives Retinoic acid (RA) and their synthetic products induce differentiation in various cell type and it has been used in the treatment of acute promyelocytic leukemia. However, effectiveness of RA in radioiodine-refractory thyroid cancer is controversial. We performed a meta-analysis to evaluate the effectiveness of RA in radioiodine-refractory thyroid cancer.

Methods We performed a systematic search of MEDLINE (from inception to September 2015) and EMBASE (from inception to September 2015) for English-language publications using the keywords “thyroid”, “retinoid”, “retinoic” and “retinoids”. All searches were limited to human studies. The inclusion criteria were studies of thyroid cancer treated with retinoic acid. Reviews, abstracts, and editorial materials were excluded, and duplicate data were removed.

Results We analysed 16 studies including 348 patients. Disease response rates were assessed by whole body scintigraphy, thyroglobulin, RECIST 1.0 criteria and WHO criteria. And it ranged between 6.2% and 50.0% with a pooled effect of 33.1% (95% CI: 27.2-39.5%), 56.6% to 83.3%, 4.8-52.8% (19.2%) and 13.8-54.2% (30.3%), respectively.

Conclusions Our meta-analysis demonstrates that treatment using RA in radioiodine-refractory thyroid cancer is partially effective. Only small group of patients showed good response on RA therapy. In patients with radioiodine-refractory thyroid cancer, RA therapy might be an optional treatment.