"The Minidose protocol is very simple, well-accepted especially under rhTSH stimulation, can be administered everywhere including areas or countries with no nuclear medicine facilities, has low costs, and has no significant secondary effects," Dr. Jerome Clerc from Universite Rene Descartes Sorbonne Paris Cité, Paris, France, told Reuters Health by email.
In a January 11 online paper in the Journal of Clinical Endocrinology & Metabolism, Dr. Clerc and colleagues reviewed their use of the Minidose protocol in 160 outpatients with low-risk DTC. Patients received 740 MBq/20 mCi on two occasions, six to 18 months apart.
Success rates were 90.1% overall after both doses, and 90.4% in patients with rhTSH-stimulated thyroglobulin levels below 10 ng/mL at Minidose 1, the authors report.
In fact, they found, rhTSH (recombinant human thyroid stimulating hormone) stimulation or stimulated thyroglobulin below 10 ng/mL at Minidose 1 were significant predictors of ablation success on multivariate analysis -- likely because they reflected smaller remnants, the researchers say.
Minidose imaging detected metastases in 5.6% of patients, including five patients with positive mediastinal nodes or distant lesions that would not have been localized by ultrasound or identified by stimulated thyroglobulin, the researchers say.
Among 81 patients with at least a year of follow-up after Minidose 1 (average, 41.8 months), no one has evidence of disease.
"The Minidose protocol permits us to separate different goals of 131I to perform the ablation (a negative stimulated thyroglobulin will make the follow-up easier), to restage about 5% of the patients with distant metastasis or nodes which may escape the Doppler-ultrasound examination (these patients will be treated at high activity or by surgery), and to quickly reassure the patients since most of them do not have a life-threatening disease," Dr. Clerc wrote in his email.
"I think most of them should receive the Minidose protocol, at least the first outpatient activity of 740 MBq," he added.
About 15 in 100,000 women and five in 100,000 men are diagnosed with DTC each year in the United States, and the incidence appears to be rising.
By Will Boggs MD
J Clin Endocrin Metab 2012.
Last Updated: 2012-02-28 13:10:06 -0400 (Reuters Health)
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