Joint statement from the Society for Endocrinology and the British Thyroid Association regarding ‘Association of Radioactive Iodine Treatment with cancer mortality in patients with hyperthyroidism’

Learning Objectives: On successful completion of this activity, participants should be able to (1) acquire knowledge on the clinical manifestations and underlying pathophysiology of the different forms of hyperthyroidism; (2) understand how to interpret ultrasound imaging and radionuclide evaluation in patients with hyperthyroidism; and (3) become familiar with the different methodological approaches to radioiodine therapy in patients with hyperthyroidism.Financial Disclosure: The authors of this article have indicated no relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through March 2023.Benign thyroid disorders, especially hyper-and hypothyroidism, are the most prevalent endocrine disorders. The most common etiologies of hyperthyroidism are autoimmune hyperthyroidism (Graves disease, GD), toxic multinodular goiter (TMNG), and toxic thyroid adenoma (TA). Less common etiologies include destructive thyroiditis (e.g., amiodarone-induced thyroid dysfunction) and factitious hyperthyroidism. GD is caused by autoantibodies against the thyroid-stimulating hormone (TSH) receptor. TMNG and TA are caused by a somatic activating gain-of-function mutation. Typical laboratory findings in patients with hyperthyroidism are low TSH, elevated free-thyroxine and free-triiodothyronine levels, and TSH-receptor autoantibodies in patients with GD. Ultrasound imaging is used to determine the size and vascularity of the thyroid gland and the location, size, number, and characteristics of thyroid nodules. Combined with lab tests, these features constitute the first-line diagnostic approach to distinguishing different forms of hyperthyroidism. Thyroid scintigraphy with either radioiodine or 99m Tc-pertechnetate is useful to characterize different forms of hyperthyroidism and provides information for planning radioiodine therapy. There are specific scintigraphic patterns for GD, TMNG, TA, and destructive thyroiditis. Scintigraphy with 99m Tcsestamibi allows differentiation of type 1 from type 2 amiodarone-induced hyperthyroidism. The radioiodine uptake test provides information for planning radioiodine therapy of hyperthyroidism. Hyperthyroidism can be treated with oral antithyroid drugs, surgical thyroidectomy, or 131 Iiodide. Radioiodine therapy is generally considered after failure of treatment with antithyroid drugs, or when surgery is contraindicated or refused by the patient. In patients with TA or TMNG, the goal of radioiodine therapy is to achieve euthyroid status. In GD, the goal of radioiodine ...

show abstract

“…Similar concern has recently been raised in the case of hyperthyroidism (74). This notion has been strongly refuted (75)(76)(77)(78)(79).…”

Section: Side Effects Of Radioiodine Therapymentioning

confidence: 73%

The Role of Nuclear Medicine in the Clinical Management of Benign Thyroid Disorders, Part 1: Hyperthyroidism

et al. 2020

View full text Add to dashboard Cite

show abstract

“…First, the individual studies included patients who were not randomized to the treatments they received, and such observational studies may be vulnerable to confounding bias. 36 However, most studies were evaluated as having relatively reliable quality for confounder control, although the individual studies may have been influenced by inadequate control for confounding by indication, which occurs when the reasons underlying the selection of a treatment are independently associated with risk of the outcome. Second, the number of studies included in the quantitative synthesis was relatively small for pooling risks of relatively uncommon cancer types despite the large sizes of the cohorts, and only 3 studies provided information of dose-response associations.…”

Section: Discussionmentioning

confidence: 99%

Cancer Risk After Radioactive Iodine Treatment for Hyperthyroidism

et al. 2021

View full text Add to dashboard Cite

Key Points Question Is radioactive iodine (RAI) therapy for hyperthyroidism associated with an increased cancer risk? Findings This systematic review and meta-analysis, including 12 observational studies and 479 452 participants, found that RAI therapy was not associated with a significant increase in overall cancer risk or site-specific cancer incidence or mortality, except for thyroid cancer. However, a linear radiation dose-response association between RAI therapy and solid cancer mortality was observed, based on 2 studies with information on RAI administered dose. Meaning Considering the global use of RAI therapy for hyperthyroidism, further studies are needed to provide quantitative estimates of site-specific cancer risks associated with RAI therapy, particularly at higher doses.

show abstract

“…The total activities of 131 I administered were more than 1.8 GBq in 12 patients, and the largest total 131 I activity administered was 3.8 GBq among the present patients. Although most studies have shown no significant increase in the prevalence of secondary malignancies in adult patients treated with typical 131 I activity (370-555 MBq) for GD [2,11], the relationship between internal exposure to 131 I and secondary malignancies remains controversial [11][12][13]. Recently, Kitahara et al [14] reported a modest positive association between the total administered 131 I activity (interquartile range: 187-422 MBq) and solid cancer mortality among RIT-treated GD patients in their multicenter cohort study.…”

Section: Discussionmentioning

confidence: 99%

Utility of outpatient fractionated radioiodine therapy for Graves disease involving a large goiter measuring more than 100 mL in volume

et al. 2021

View full text Add to dashboard Cite

Contrary to large multinodular goiters, reports on 131 I radioiodine therapy (RIT) for Graves disease (GD) involving a large goiter are scarce. We retrospectively reviewed a total of 71 consecutive patients (25 males, 46 females) with GD involving a large goiter (>100 mL) who had received RIT in our clinic. Patients with a history of thyroid surgery or with large thyroid nodules and those who had dropped out less than one year after the initial RIT session were excluded. A fixed 131 I activity of 481 MBq was administered in most cases. RIT was repeated at intervals of 1-47 months, typically 3-6 months. The follow-up duration after the initial RIT session was 13-233 (median: 81) months. The thyroid volume was estimated using ultrasound. The number of 131 I doses were 1 dose in 13 patients, 2 doses in 29, 3 doses in 17, 4 doses in 5, 5 doses in 5, 6 doses in 1, and 8 doses in 1. Sixty-six patients had remission from overt hyperthyroidism after RIT: overt hypothyroidism in 45 patients, subclinical hypothyroidism or euthyroidism in 13, and subclinical hyperthyroidism in 8. Their thyroid volume decreased from 101-481 (median: 126) mL to 1.4-37 (8.2) mL. Three patients still had overt hyperthyroidism under treatment with methimazole after one to three doses, and two dropped out less than six months after the third or sixth dose. Even in GD patients with a large goiter (>100 mL), repeated RIT with an activity of 481 MBq could sufficiently shrink goiters and remit overt hyperthyroidism.

show abstract

Joint statement from the Society for Endocrinology and the British Thyroid Association regarding ‘Association of Radioactive Iodine Treatment with cancer mortality in patients with hyperthyroidism’

Cited by 15 publications

References 16 publications

The Role of Nuclear Medicine in the Clinical Management of Benign Thyroid Disorders, Part 1: Hyperthyroidism

The Role of Nuclear Medicine in the Clinical Management of Benign Thyroid Disorders, Part 1: Hyperthyroidism

Cancer Risk After Radioactive Iodine Treatment for Hyperthyroidism

Utility of outpatient fractionated radioiodine therapy for Graves disease involving a large goiter measuring more than 100 mL in volume

Contact Info

Product

Resources

About