"High-dose" radioiodine therapy in advanced differentiated thyroid carcinoma.
There is yet no consensus concerning the appropriate regimen of the application of [131I]sodium iodine (Nal) activities to patients suffering from advanced differentiated thyroid carcinoma. We report on a total of 167 applications of [131I]Nal, including 78 applications of 11.1 GBq. Response to high-activity radioiodine therapy (RIT) is correlated to the course of the disease as well as to the reaction of thyreoglobulin and acute/subacute side effects of radiation.


METHODS
Following radioablation of thyroid remnants using 1.85 to 3.7 GBq[131I]Nal, 26 patients with advanced differentiated thyroid carcinoma (follicular, 11; papillary, 4;mixed-cell thyroid carcinoma, 11) were treated with repeated activities of 11.1 GBq[131I]Nal. Initial tumor staging according to UICC showed T4 in 54%, T3 in 19%, T2 in 19% and was not obtained in 8%. Differentiated thyroid carcinoma was multifocal in 23% of patients. Applied accumulated activities ranged from 14.8 to 99.9 GBq with a mean of 55.5 GBq per patient.


RESULTS
Mean post-diagnostical follow-up was 73 mo, mean follow-up after diagnosis of metastatic spread was 48 mo. Follicular thyroid carcinoma remained as stable disease in 7 of 11 patients, 6 of whom showed metastatic disease after a mean of 20 mo, and only 1 complete remission was achieved using high-dose therapies, with progressive disease in the remaining patients. Overall, 73% of follicular thyroid carcinoma had progressive disease without major response to high-activity RIT. In contrast, only 20% of papillary thyroid carcinoma/mixed-cell thyroid carcinoma showed progressive disease, and complete remission was achieved in 47% of patients. Pulmonary and lymph node metastases in the majority of patients showed good response to therapy, whereas local recurrences and bone metastases showed minor reactions to RIT. After low-activity therapies 8% of patients showed WHO grade I hematotoxic reactions. After high-activity therapies, 38% of patients had WHO I, 8% WHO II and one patient had WHO III toxicity (4%).


CONCLUSIONS
Use repetitive high-activity RIT with a maximum of 44.4 GBq applied during 1 yr and a maximum of 99.9 GBq accumulated activity resulted in a significant increase of hematotoxicity. However, during the follow-up period (mean, 4 yr), no clinical symptoms possibly related to low blood counts were seen in patients with advanced differentiated thyroid carcinoma. Initiation of high-activity RIT in reaction to metastatic tumor outspread to achieve complete remission was found to be useful in treating papillary thyroid carcinoma and mixed-cell thyroid carcinoma, but only in a minority of follicular thyroid carcinoma patients.
Menzel
C
C
Department of Nuclear Medicine, University of Bonn, Germany.
Grünwald
F
F
Schomburg
A
A
Palmedo
H
H
Bender
H
H
Späth
G
G
Biersack
H J
HJ
D018263:Adenocarcinoma, Follicular / Q000401:mortality / Q000532:radiotherapy*; D002291:Carcinoma, Papillary / Q000401:mortality / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D012974:Sodium Iodide / Q000627:therapeutic use; D015996:Survival Rate; D013964:Thyroid Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D013997:Time Factors; D016896:Treatment Outcome
D007457:Iodine Radioisotopes; D012974:Sodium Iodide