The benefits of radioiodine therapy (RIT) for metastatic poor differentiated thyroid cancer (PDTC) not quite clear, so we made a retrospective evaluation of the outcome of RIT for metastatic PDTC.
Through May 2007 to April 2012, we experienced 11 cases of RIT for metastatic PDTC. 3 males and 8 females with an average age of 67.7 at the point of RIT. In 6 cases metastasis were detected before thyroidectomy and in the remaining 5 cases were detected while follow up. The average age of each group at the time of surgery was 72.2 and 54.9, at the time of RIT 72.2, 62.4. All cases had an administration of 3700MBq (100mCi) of radioiodine for initial RIT. 6 out of the 11 cases had radioiodine avid lesions and 5 cases had non-avid lesions. The mean follow up period after surgery was 113.4 month (10-312), after RIT was 71.0 month (7-139).
During follow up, 6 out of 11 cases died due to thyroid cancer and 4 cases had progressive disease with increasing metastasis or elevating serum Tg. Only 1 case was controlled. 5 out of 6 cases that have died were cases with metastasis at the time of thyroidectomy. In the cases detected while follow up, only one died, although 3 cases had progressive disease. From a RIT point of view, 3 died and 2 had progressive disease in the cases with non-avid lesions, but 3 out of 6 died and 2 had progressive disease in cases with radio iodine avid lesions. Radioiodine avidity did not have any impact to the outcome.
Although RIT is still considered as the first line treatment for metastatic PDTC RIT does not seem to have a large impact for metastatic PDTC.