According to pathology, thyroid cancer can be divided into: papillary thyroid cancer, follicular thyroid cancer, medullary carcinoma and undifferentiated carcinoma. Among them, papillary thyroid cancer and follicular thyroid cancer are collectively referred to as differentiated thyroid cancer, and their degree and characteristics of differentiation are relatively close to normal thyroid tissue, which can absorb iodine like normal thyroid cells.
Differentiated thyroid cancer loves to "eat" iodine, iodine-131 is the "same brother" of ordinary iodine, but it can release β rays, which are not strong in penetration, but destructive. Iodine-131 enters the body, "mixes itself with ordinary iodine", and does its best for differentiated thyroid cancer, when differentiated thyroid cancer cells absorb it together with ordinary iodine, it continues to emit β rays, radiating differentiated thyroid cancer cells, so that differentiated thyroid cancer cells unconsciously "apoptosis".
At present, for differentiated thyroid cancer, the standardized treatment of "surgical removal of thyroid gland + selective iodine-131 treatment + thyroxine replacement" is generally used, of which iodine-131 treatment is an important adjunctive treatment method to prevent recurrence and metastasis after thyroid cancer. However, there is no direct evidence that postoperative use of iodine-131 is beneficial for prognosis in patients with low-risk differentiated thyroid cancer undergoing thyroidectomy.
To this end, scholars from France conducted a prospective randomized Phase 3 trial in which patients with low-risk differentiated thyroid cancer who underwent thyroidectomy were assigned to radioactive iodine (1.1 GBq) ablation after injection of recombinant human thyroxine (radioactive iodine group) or postoperative radioactive iodine therapy (no radioactive iodine group). The main objective is to assess whether treatment without radioactive iodine is not inferior to radioactive iodine therapy for 3 years. The results were published in the journal NEJM.
The results showed that among the 730 patients who could be evaluated after 3 years of randomization, the proportion of patients without events was 95.6% (95% CI, 93.0-97.5) in the radioactive iodine group, 95.9% (95% CI, 93.3-97.7), and the difference was -0.3% (bilateral 90% CI, -2.7 to 2.2), which met the criteria for non-inferiority.
Related events included structural or functional abnormalities in 8 patients and biological abnormalities in 23 patients over a 3-year period. During thyroid hormone therapy, events are more frequent in patients with postoperative serum thyroglobulin levels exceeding 1 ng/mL. In patients with or without events, molecular alterations are similar.
In summary, in low-risk thyroid cancer patients undergoing thyroidectomy, the follow-up strategy without radioactive iodine was no less than the ablation strategy using radioactive iodine in terms of function, structure, and incidence of biological events over a 3-year period.
bibliography:
Thyroidectomy without Radioiodine in Patients with Low-Risk Thyroid Cancer. N Engl J Med 2022; 386:923-932. DOI: 10.1056/NEJMoa2111953
Written by | Dr. Apathy
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