Benefit From Second Radioiodine Treatment for Differentiated Thyroid Cancer

There is limited benefit from a second treatment of radioactive iodine in patients with differentiated thyroid cancer and persistent biochemical or regional disease, according to a study published in the Journal of Clinical Endocrinology & Metabolism.¹

Researchers identified 164 patients with differentiated thyroid cancer who had an incomplete response to initial treatment, had no evidence of distant metastases, and underwent at least 2 radioactive iodine treatments from a hospital thyroid cancer registry in Israel.1 They were followed for a median duration of 10 years from diagnosis and 7.4 years from the second treatment. 

Of 60 patients with complete data who had a biochemical incomplete response to initial treatment, 44 still had an elevated thyroglobulin level at 1 to 2 years after the second radioactive iodine treatment.1 Of 50 patients with a structural incomplete response to initial treatment and neck reoperation before the second treatment, there was no significant difference in mean stimulated or nonstimulated thyroglobulin level between baseline and 1 to 2 years after the second radioactive iodine treatment.

Similar results were demonstrated in 53 patients with a structural incomplete response to initial treatment who did not have a neck reoperation before the second treatment. At final follow-up, 63 patients underwent additional treatment after the second radioactive iodine treatment; however, only 34.1% (56/164) demonstrated no evidence of disease. 

These findings are consistent with other studies that have also demonstrated limited value after a second radioactive iodine treatment in patients with differentiated thyroid cancer and locoregional residual disease.^2-7 

The investigators concluded that, “While we cannot exclude a therapeutic effect of the second [radioactive iodine] dose, our data may aid in establishing realistic expectations of patients and physicians regarding this treatment. Prospective studies are needed to identify patients for whom repeated [radioactive iodine] treatment may be indicated in order [to] spare the remainder unnecessary exposure.”¹

References

1. Hirsch D, Gorshtein A, Robenshtok E, et al. Second radioiodine treatment: limited benefit for differentiated thyroid cancer with loforegional persistent disease [published online November 3, 2017]. J Clin Endocrinol Metab. doi: 10.1210/jc.2017-01790
2. Yim JH, Kim WB, Kim EY, et al. Adjuvant radioactive therapy after reoperation for locoregionally recurrent papillary thyroid cancer in patients who initially underwent total thyroidectomy and high-dose remnant ablation. J Clin Endocrinol Metab. 2011;96:3695-3700
3. Yim JH, Kim WB, Kim EY, et al. The outcomes of first reoperation for locoregionally recurrent/persistent papillary thyroid carcinoma in patients who initially underwent total thyroidectomy and remnant ablation. J Clin Endocrinol Metab. 2011;96:2049-2056
4. Piccardo A, Puntoni M, Bottoni G, et al. Differentiated thyroid cancer lymph-node relapse. Role of adjuvant radioactive iodine therapy after lymphadenectomy. Eur J Nucl Med Mol Imaging. 2017;44:926-934
5. Haugen BR, Alexander EK, Bible KC, et al. American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016;26:1-133
6. Vaisman F, Tala H, Grewal R, Tuttle RM. In differentiated thyroid cancer, an incomplete structural response to therapy is associated with significantly worse clinical outcomes than only an incomplete thyroglobulin response. Thyroid. 2011;21:1317-1322
7. Grant CS, Hay ID, Gough IR, Bergstralh EJ, Goellner JR, McConahey WM. Local recurrence in papillary thyroid carcinoma: is extent of surgical resection important? Surgery. 1988;104:954-962