Maximal safe dose of I-131 after failure of standard fixed dose therapy in patients with differentiated thyroid carcinoma

Jong Jin Lee, June Key Chung, Sung Eun Kim, Won Jun Kang, Do Joon Park, Dong Soo Lee, Bo Youn Cho, Myung Chul Lee

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46 Citations (Scopus)


Objective: The maximal safe dose (MSD) on the basis of bone marrow irradiation levels allows the delivery of a large amount of I-131 to thyroid cancer tissue. The efficacy of MSD therapy in differentiated metastatic thyroid cancers that persisted after conventional fixed dose therapy is investigated. Methods: Forty-seven differentiated thyroid carcinoma patients with non-responsive residual disease despite repetitive fixed dose I-131 therapy were enrolled in this study. Their postoperative pathologies were 43 papillary carcinomas and 4 follicular carcinomas. The MSD was calculated with the Memorial Sloan-Kettering Cancer Center protocol using serial blood samples. The MSDs were administered at intervals of 6 months. Treatment responses were evaluated using I-131 whole-body scans and serum thyroglobulin measurements. Results: The mean calculated MSD was 12.5 ± 2.1 GBq (339.6 ± 57.5 mCi). Of the 46 patients, 7 (14.9%) showed complete remission, 15 (31.9%) partial remission, 19 (40.4%) stable disease, and 6 (12.8%) disease progression. Of the patients who showed complete or partial remission, 15 (65%) showed response after the first MSD session and 6 (26%) showed response after the second session. Twenty-nine patients (62%) experienced transient cytopenia after therapy, but three did not recover to the baseline level. Conclusions: The maximal safe dose provides an effective means of treatment in patients who failed to respond adequately to conventional fixed dose therapy. I-131 MSD therapy can be considered in patients who fail fixed dose therapy.

Original languageEnglish
Pages (from-to)727-734
Number of pages8
JournalAnnals of Nuclear Medicine
Issue number9
Publication statusPublished - 2008 Nov
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgment This study was supported by the Korean Research Foundation, Republic of Korea (#2000-042-P00084).


  • I-131 therapy
  • Maximal safe dose
  • Thyroid carcinoma

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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