The success rate of I-131 ablation in differentiated thyroid cancer: comparison of uptake-related and fixed-dose strategies.
BACKGROUND
The aim of the study was to compare the success rate of an uptake-related ablation protocol in which the dose depends on an I-131 24-h neck uptake measurement and a fixed-dose ablation protocol in which the dose depends on tumour stage.


METHODS
All differentiated thyroid carcinoma patients with M0 disease who had undergone (near-) total thyroidectomy followed by I-131 ablation were included. In the uptake-related ablation protocol, 1100 (uptake >10%), 1850 (uptake 5-10%) and 2800 MBq (uptake <5%) were used. In the fixed-dosage ablation strategy, 3700 (T1-3, N0 stage) and 5550 MBq (N1 and/or T4 stage) were applied. We used I-131 uptake on whole-body scintigraphy and thyroglobulin-off values to evaluate the ablation 6-12 months after treatment.


RESULTS
In the uptake-related ablation protocol, 60 out of 139 (43%) patients were successfully treated versus 111 out of 199 for the fixed-dose ablation protocol (56%) (P=0.022). The differences were not statistically significant for patients with T4 (P=0.581) and/or N1 (P=0.08) disease or for patients with T4N1 tumour stage (P=0.937).


CONCLUSIONS
The fixed-dose I-131 ablation protocol is more effective in ablation of the thyroid remnant in differentiated thyroid carcinoma patients than an uptake-related ablation protocol. This difference is not observed in patients with a N1 and/or T4 tumour stage.
Division of Nuclear Medicine, Department of Radiology, Leiden University Medical Center, C4-Q, Albinusdreef 2, PO Box 9600, 2300 RC Leiden, The Netherlands.
Robbert B T
RB
Verkooijen
Frederik A
FA
Verburg
Johannes W
JW
van Isselt
Cornelis J M
CJ
Lips
Jan W
JW
Smit
Marcel P M
MP
Stokkel
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018265:Carcinoma, Papillary, Follicular / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D003131:Combined Modality Therapy; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D013964:Thyroid Neoplasms / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D013965:Thyroidectomy; D016896:Treatment Outcome
D007457:Iodine Radioisotopes