Reassessing the standard: Radioiodine therapy for thyroid cancer

Radioiodine therapy has been around for a long time now as an effective treatment for thyroid cancer. However there may be some scenarios in which an alternative or combined treatment may be better suited, according to a review published Aug. 11 in the Journal of Nuclear Medicine.

Daniel A. Pryma, MD, from the division of nuclear medicine and clinical molecular imaging in the department of radiology, and Susan J. Mandel, MD, from the division of endocrinology, diabetes and metabolism in the department of medicine at the Perelman School of Medicine, University of Pennsylvania in Philadelphia, evaluated the current standard of care for thyroid cancer patients and specifically the use of radioiodine therapy. The researchers presented a couple of cases in which a dial-down in dose is suggested and others in which another approach should be sought.

“Radioiodine is a prototypical theranostic agent permitting both imaging and therapy,” wrote Pryma and Mandel. “The therapeutic use of radioiodine continues to be refined with a better understanding of the risks and benefits of therapy. It is hoped that this refinement will permit decreased (or absent) dose (and decreased toxicity) in the patients who are destined to do well, increased dose in the patients who will benefit from treatment, and more appropriate discontinuation or modification of therapy in those unlikely to benefit from single-agent radio-iodine therapy.”

The researchers present I-124 PET/CT as a tool for more accurate clinical decision making in terms of expected response to therapy. Targeted therapies could also be used by itself or in conjunction with radioiodine in not only adjuvant thyroid cancer cases but advanced cases as well, and the researchers urge clinicians to advise the care team when a targeted therapy would be beneficial.

“Nuclear medicine physicians should play a key consultative role in the treating team to optimize radioiodine therapy and confirm the presence or absence of iodine-refractory disease,” the researchers wrote. “Multiple targeted therapeutics are being tested in the setting of iodine-refractory thyroid cancer, with one agent now approved in the United States.”

That FDA-approved targeted therapy is sorafenib (Nexavar), approved November 2013 for cases of late-stage or recurrent differentiated thyroid cancer. However, access to targeted therapies should not discourage clinicians from using radioiodine therapy when it is needed. 

“Although it is excellent for patients with iodine-refractory disease to have options, it is critically important to recognize that radioiodine is an effective treatment in a large subset of patients with metastatic differentiated thyroid cancer and should not be abandoned prematurely (nor should it be used when there is evidence of its futility).”

Rather than used as a replacement, targeted therapies will likely join radioiodine therapies as a united front in multiagent treatments for the best possible treatment of thyroid cancer.