Diagnostic 131I whole-body scintigraphy 1 year after thyroablative therapy in patients with differentiated thyroid cancer: correlation of results to the individual risk profile and long-term follow-up
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- Berger, F., Friedrich, U., Knesewitsch, P. et al. Eur J Nucl Med Mol Imaging (2011) 38: 451. doi:10.1007/s00259-010-1657-0
131I whole-body scan (WBS) and serum thyroglobulin (TG) are important in detecting thyroid remnants or recurrent disease in patients with differentiated thyroid cancer. Usually, a diagnostic WBS is carried out 6 months after ablation to exclude residual disease. We retrospectively analysed results of a second routine diagnostic WBS and TG measurements at 1 year after thyroablation and correlated these to the risk profile of patients with long-term follow-up.
A total of 197 patients were followed up after thyroidectomy and ablative 131I therapy. Follow-up included clinical examination, radioiodine WBS and thyroid-stimulating hormone (TSH), free thyroxine and TG measurements at 3–6 months and 1 year after ablation. WBS (+) patients received a therapeutic activity of 131I. The risk profile of patients was defined according to clinical results before the 1-year control. Clinical results at 1 year after ablation were analysed in correlation to the patient risk profile and long-term follow-up data (mean 7.2 years).
One year after thyroablation, 95.8% of low-risk patients had no residual disease when diagnostic WBS was carried out using 370 MBq 131I; 4.2% of low-risk patients had residual disease at this time point. In the high-risk group of this cohort, 54.5% were disease-free 1 year after ablation, but 45.5% demonstrated residual disease. After the 1-year control, 94% of all applied radioiodine therapies were executed in the high-risk group, compared with 6% in the low-risk group (p < 0.01).
A second routine WBS 1 year after thyroablation is not indicated in low-risk patients. Risk stratification according to the early clinical course effectively identified patients with higher likelihood of persistent or recurrent disease in the long-term follow-up.