The benefits and risks of I-131 therapy in patients with well-differentiated thyroid cancer.
BACKGROUND
I-131 has been used in the therapy of well-differentiated thyroid cancer for over 50 years. Although the benefits and risks of I-131 remain issues of controversy and research, our understanding of them continues to improve. This review presents an overview of the benefits of I-131 therapy for ablation, adjuvant treatment, and treatment of locoregional and/or metastasis of well-differentiated thyroid cancer and considers the risks of complications of I-131 therapy.


CONCLUSIONS
The benefits of I-131 remnant ablation include: [1] facilitating the interpretation of subsequent serum thyroglobulin levels, [2] increasing the sensitivity of detection of locoregional and/or metastatic disease on subsequent follow-up radioactive iodine whole-body scans, [3] maximizing the therapeutic effect of subsequent treatments, and [4] allowing a postablation scan to help identify additional sites of disease that were not identified on the preablation scan or when a preablation scan was not performed. The potential benefits of I-131 adjuvant treatment include decreasing recurrence and disease-specific mortality for unknown microscopic, locoregional, and/or distant metastatic disease. The potential benefits of I-131 treatment of known locoregional and/or distant metastases are [1] decreasing recurrence, and [2] decreasing disease-specific mortality and/or palliation. The more significant risks and side effects involve organ systems including eye/nasolacrimal, salivary, pulmonary, gastrointestinal, hematopoietic, and gonads as well as secondary primary malignancies.


CONCLUSIONS
Although there are never-ending controversies regarding I-131 therapy in well-differentiated thyroid cancer, the benefits and risks are becoming better understood. This in turn helps the treating physician and patient in making decisions regarding therapy.
Van Nostrand
Douglas
D
Division of Nuclear Medicine, and Nuclear Medicine Residency Program, Washington Hospital Center , Washington, District of Columbia, USA. douglas.van.nostrand@medstar.net
D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*; D008175:Lung Neoplasms / Q000532:radiotherapy / Q000556:secondary; D016609:Neoplasms, Second Primary / Q000209:etiology; D018714:Radiotherapy, Adjuvant; D018570:Risk Assessment; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D051598:Whole Body Imaging
D007457:Iodine Radioisotopes; D013954:Thyroglobulin