Radioactive Iodine: A Living History

RAI therapy in low-risk papillary thyroid cancer: recurrence reduction and long-term outcomes in the Turkish population

PURPOSE

Papillary thyroid cancer (PTC) is the most common thyroid malignancy, characterized by its slow progression and favorable prognosis. This study re-evaluates the efficacy of radioactive iodine (RAI) therapy versus no RAI in low-risk PTC patients following total thyroidectomy.

METHODS

A retrospective analysis was conducted on 588 patients treated between 2010 and 2016 at a major tertiary center in Turkey. Patients were divided into two cohorts: those receiving total thyroidectomy (TT) with high-dose RAI (100 mCi) and those receiving TT alone. A matched cohort of 138 patients per group was analyzed to minimize bias.

RESULTS

Follow-up data indicated that at 24 months, the RAI group demonstrated a higher percentage of excellent treatment responses (86%) compared to the non-RAI group (74%). Long-term follow-up showed that 99.3% of the RAI group achieved no evidence of disease (NED), versus 90.6% in the non-RAI group. Recurrence rates were significantly lower in the RAI group (1%) compared to the non-RAI group (5.8% with a > 2.0 ng/ml cut-off for biological events).

CONCLUSION

In summary, the findings from this study underscore the efficacy of RAI therapy in reducing recurrence rates and enhancing long-term disease control in low-risk papillary thyroid cancer patients. While total thyroidectomy alone is effective, the addition of RAI therapy provides a marked improvement in treatment responses and reduces the risk of disease recurrence. This indicates that personalized treatment plans incorporating RAI may offer significant advantages in managing low-risk PTC.

Alpha and Beta Radiation for Theragnostics

Targeted radionuclide therapy (TRT) has significantly evolved from its beginnings with iodine-131 to employing carrier molecules with beta emitting isotopes like lutetium-177. With the success of Lu-177-DOTATATE for neuroendocrine tumors and Lu-177-PSMA-617 for prostate cancer, several other beta emitting radioisotopes, such as Cu-67 and Tb-161, are being explored for TRT. The field has also expanded into targeted alpha therapy (TAT) with agents like radium-223 for bone metastases in prostate cancer, and several other alpha emitter radioisotopes with carrier molecules, such as Ac-225, and Pb-212 under clinical trials. Despite these advancements, the scope of TRT in treating diverse solid tumors and integration with other therapies like immunotherapy remains under investigation. The success of antibody-drug conjugates further complements treatments with TRT, though challenges in treatment optimization continue.

Optimizing the indication of initial radioiodine oncolytic treatment for metastatic differentiated thyroid cancer by diagnostic 131I scan

AIM

As a classic theranostic radiopharmaceutical, radioiodine (131I) has been utilized in the management of differentiated thyroid cancer (DTC) for more than 8 decades, and the refinement of its clinical practice has been raised recently. This study was conducted to evaluate the efficiency of a diagnostic (Dx) 131I scan in optimizing the indication of initial radioiodine oncolytic treatment (ROT) for metastatic DTC by predicting therapeutic outcomes.

RESULTS

A total of 100 patients (Dx positive, n=29; Dx negative, n=71) were eligible for patient-based analysis. The matching rate was 83.0% between the Dx and the post-therapeutic scans (kappa = 0.648, P<0.001). The biochemical remission rate and structural shrinkage rate induced by the initial ROT in the Dx-positive group were, respectively, greater than those in the Dx-negative group (83.3% vs. 17.4%, P<0.001; 37.9% vs. 4.2%, P<0.001). Notably, the predictive values of positive Dx scans for ROT responsiveness and negative Dx scans for ROT nonresponsiveness reached up to 89.7% and 84.5%, respectively.

CONCLUSION

This Dx scan approach seems viable in characterizing the 131I-avidity of metastatic DTC and plays a pivotal role in optimizing the indication of initial ROT for metastatic DTC.

Radionuclide Theranostics in Neuroendocrine Neoplasms: An Update

PURPOSE OF REVIEW

This paper aims to address the latest findings in neuroendocrine tumor (NET) theranostics, focusing on new evidence and future directions of combined diagnosis with positron emission tomography (PET) and treatment with peptide receptor radionuclide therapy (PRRT).

RECENT FINDINGS

Following NETTER-1 trial, PRRT with [177Lu]Lu-DOTATATE was approved by FDA and EMA and is routinely employed in advanced G1 and G2 SST (somatostatin receptor)-expressing NET. Different approaches have been proposed so far to improve the PRRT therapeutic index, encompassing re-treatment protocols, combinations with other therapies and novel indications. Molecular imaging holds a potential added value in characterizing disease biology and heterogeneity using different radiopharmaceuticals (e.g., SST and FDG) and may provide predictive and prognostic parameters. Response assessment criteria are still an unmet need and new theranostic pairs showed preliminary encouraging results. PRRT for NET has become a paradigm of modern theranostics. PRRT holds a favorable toxicity profile, and it is associated with a prolonged time to progression, reduction of symptoms, and improved patients' quality of life. In light of further optimization, different new strategies have been investigated, along with the development of new radiopharmaceuticals.

Molecular Imaging and Therapy of Differentiated Thyroid Carcinoma in Adults

ABSTRACT

Differentiated thyroid carcinoma (DTC) has been increasing in incidence in the United States over the last several decades, although mortality rates have remained low. Radioactive iodine therapy (RAI-T) has been a mainstay of treatment for DTC since the 1940s. Imaging of DTC before and after RAI-T primarily focuses on molecular imaging of the sodium iodide symporter. The expanding understanding of the molecular profile of DTC has increased available treatment options. Incorporation of risk stratification to treatment approaches has led to deintensification of both surgical and nonsurgical treatments, leading to decreased morbidity without compromising disease control.

Summary and update on the management of differentiated thyroid cancer in 2023

The 6-fold increase in the incidence of differentiated thyroid cancer over the past 30 years in industrialized countries can be mainly attributed to improved detection. At the same time, in addition to the excellent prognosis for low-risk cancers, improved survival in metastatic forms has been also reported, likely due to the progress made recently in the treatment of aggressive forms, for which there is now an extensive therapeutic arsenal. Today, clinical management of differentiated thyroid cancer represents a paradigm of precision oncology, with personalized, risk-adapted therapeutic strategies. This has led to therapeutic de-escalation in those forms with a good prognosis, while targeted treatments play an increasingly important role in the management of radioiodine-refractory or advanced cancers. While endocrinologists will not always have the opportunity to prescribe these treatments, they will be called on to support and monitor patients during treatment. The aim of this article is to provide an overview of treatment options for differentiated thyroid cancer in 2023.

Enhanced predictive validity of integrative models for refractory hyperthyroidism considering baseline and early therapy characteristics: a prospective cohort study

BACKGROUND

A subset of Graves' disease (GD) patients develops refractory hyperthyroidism, posing challenges in treatment decisions. The predictive value of baseline characteristics and early therapy indicators in identifying high risk individuals is an area worth exploration.

METHODS

A prospective cohort study (2018-2022) involved 597 newly diagnosed adult GD patients undergoing methimazole (MMI) treatment. Baseline characteristics and 3-month therapy parameters were utilized to develop predictive models for refractory GD, considering antithyroid drug (ATD) dosage regimens.

RESULTS

Among 346 patients analyzed, 49.7% developed ATD-refractory GD, marked by recurrence and sustained Thyrotropin Receptor Antibody (TRAb) positivity. Key baseline factors, including younger age, Graves' ophthalmopathy (GO), larger goiter size, and higher initial free triiodothyronine (fT3), free thyroxine (fT4), and TRAb levels, were all significantly associated with an increased risk of refractory GD, forming the baseline predictive model (Model A). Subsequent analysis based on MMI cumulative dosage at 3 months resulted in two subgroups: a high cumulative dosage group (average ≥ 20 mg/day) and a medium-low cumulative dosage group (average < 20 mg/day). Absolute values, percentage changes, and cumulative values of thyroid function and autoantibodies at 3 months were analyzed. Two combined predictive models, Model B (high cumulative dosage) and Model C (medium-low cumulative dosage), were developed based on stepwise regression and multivariate analysis, incorporating additional 3-month parameters beyond the baseline. In both groups, these combined models outperformed the baseline model in terms of discriminative ability (measured by AUC), concordance with actual outcomes (66.2% comprehensive improvement), and risk classification accuracy (especially for Class I and II patients with baseline predictive risk < 71%). The reliability of the above models was confirmed through additional analysis using random forests. This study also explored ATD dosage regimens, revealing differences in refractory outcomes between predicted risk groups. However, adjusting MMI dosage after early risk assessment did not conclusively improve the prognosis of refractory GD.

CONCLUSION

Integrating baseline and early therapy characteristics enhances the predictive capability for refractory GD outcomes. The study provides valuable insights into refining risk assessment and guiding personalized treatment decisions for GD patients.

The management of pediatric Graves' disease

PURPOSE OF REVIEW

Graves' disease (GD) constitutes a significant proportion of thyroid disorders seen during childhood. Several specialties may be closely involved in the management of pediatric patients with GD and emerging research in each field contributes to variations in the approach over time. Here we review the recent literature on the management of the disease, with the hope that this can be a valuable resource for treating specialists who need to be continuously updated on new data obtained in relevant fields.

RECENT FINDINGS

Genetic, postinfectious and environmental factors may play a role in the immunological pathophysiology of GD. Research performed during the COVID-19 pandemic supports that viral-induced immune dysregulation may be a possible trigger for the disease. The various current treatment options all have positive and negative factors to consider. Antithyroidal drug therapy (ATD) is generally recommended as the initial treatment, although remission rates are only 20-30% at 2 years and 75% at 9 years. Unfortunately, about half of patients will relapse within 1 year of discontinuing therapy. Radioactive iodine therapy (RAI) is an effective treatment option and can be considered in certain pediatric patients. There continues to be no definitive evidence that the doses used for GD lead to a higher risk of cancer. Surgical treatment via thyroidectomy is effective and safe when performed by a high-volume surgeon. Recent studies show improvement in quality-of-life after surgery in adolescents and young adults. Future medical treatment options for GD currently being studied include antigen-specific immunotherapy and monoclonal antibodies.

SUMMARY

Although the future holds promising new therapeutic options for autoimmune diseases including GD, the current choices continue to be ATD, usually first-line, and definitive treatments including RAI and surgery. While all three offer the possibility of remission or cure, drug therapy and RAI have a possibility of relapse. Risks of each approach should be broached in detail with patients and their families, and the nuances of treating this disease specifically in children should be familiar to all treating providers.