title: Retinoic acid therapy in patients with radioiodine negative differentiated thyroid cancer and clinical or biochemical evidence of disease: An initial experience.
abstract: BACKGROUND
  Dedifferentiation of thyroid follicular cells renders radioiodine therapy ineffective in patients of differentiated thyroid cancer (DTC). An alternative therapy to treat the disease or reinduce radioiodine uptake is necessary.
  
  
  METHODS
  We evaluated the role of retinoic acid therapy in 13 cases of DTC with raised thyroglobulin and/or clinically evident disease. Retinoic acid was given in a dose of 1.5 mg/kg for a period ranging between 1.5 and 18 months.
  
  
  RESULTS
  Age of the patients was between 18 and 65 years with a median of 49 years. Ten patients had papillary while two had follicular and one patient had mixed papillary and follicular thyroid cancer. Mean radioiodine given before starting retinoic acid was 164 mCi. Mean duration of therapy was 6.4 months. Thyroglobulin decreased in 2 patients and increased in 11 patients at the end of therapy. Radioiodine uptake was demonstrable in six patients, though faintly, while 7 cases showed no uptake. Based on the clinical and biochemical parameters, four patients had progressive disease, eight had stable disease and one patient showed partial response. Of the six patients with reinduction of radioiodine uptake, three had biochemical progression and the other three had stable disease.
  
  
  CONCLUSIONS
  Our findings suggest that retinoic acid therapy may induce radioiodine uptake and reduce serum thyroglobulin levels in some patients with DTC, but whether this results in clinically significant response can only be ascertained on long-term follow-up.
authors: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors: Nishikant
authors: N
authors: Damle
authors: Manish
authors: M
authors: Patnecha
authors: Praveen
authors: P
authors: Kumar
authors: Sagar
authors: S
authors: Maharjan
authors: Chandrasekhar
authors: C
authors: Bal
keywords: Radioiodine; redifferentiation; retinoic acid; thyroglobulin