Retinoic acid for redifferentiation of thyroid cancer--does it hold its promise?
OBJECTIVE
To evaluate the effectiveness of isotretinoin for improving (131)I uptake in recurrent/metastasized thyroid cancer with no/insufficient (131)I uptake.


METHODS
Retrospective analysis of 25 patients treated between June 1999 and May 2001.


METHODS
15 female and 10 male patients were given isotretinoin at 1 mg/kg for 3 months, followed by (131)I treatment. All patients received a (131)I scan 72 h after administration, thyroglobulin measurement, chest X-ray and ultrasound of the neck, and some patients underwent a (18)F-fluorodeoxyglucose (FDG) positron emission tomography (n=14) and computed tomography scan of the chest (n=11).


RESULTS
In two out of 14 patients with raised thyroglobulin but no (131)I uptake, a slightly improved (131)I uptake was seen. In a further 11 patients an improvement of (131)I uptake of known lesions was desired or further non-(131)I-accumulating lesions were known. A dosimetrically relevant improvement of uptake was seen in three of these patients. (18)F-FDG uptake and thyroglobulin did not correlate with the success/failure of the isotretinoin treatment. Side effects including a strong "sunburn", cheilitis, mucositis, conjunctivitis and raised transaminases occurred in two-thirds of patients. They were of an overall tolerable level and were reversible after isotretinoin had been stopped.


CONCLUSIONS
From our clinical experience over a period of 2 years we conclude that the therapeutic effect of isotretinoin in thyroid cancer is certainly less than previously reported. An indiscriminate use of isotretinoin in all patients with otherwise untreatable thyroid cancer cannot be recommended.
Grüning
Thomas
T
Department of Nuclear Medicine, Carl Gustav Carus Medical School, University of Dresden, Fetscherstrasse 74, 01307 Dresden, Germany. Thomas.Gruning@phnt.swest.nhs.uk
Tiepolt
Claudia
C
Zöphel
Klaus
K
Bredow
Jan
J
Kropp
Joachim
J
Franke
Wolf-Gunter
WG
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000532:radiotherapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000532:radiotherapy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics* / Q000627:therapeutic use; D015474:Isotretinoin / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome
D007457:Iodine Radioisotopes; D019788:Fluorodeoxyglucose F18; D015474:Isotretinoin