Correction for hyperfunctioning radiation-induced stunning (CHRIS) in benign thyroid diseases

The influence of thyroid hormone medication on intra-therapeutic half-life of 131I during radioiodine therapy of solitary toxic thyroid nodules

Despite a significantly improved dietary iodine supply, solitary toxic thyroid nodules (STN) are still a common clinical problem in former iodine deficient areas. Radioiodine treatment (RIT) is a well-established therapeutic option with few side effects and high success rates. As radioiodine biokinetics are individual for every patient, the necessary activity has to be calculated individually by a pre-therapeutic measurement of the intra-therapeutic effective half-life (EHL) in a radioiodine uptake test (RIUT). A suppressive medication with triiodothyronine (T3) or tetraiodothyronine (T4) is often needed to suppress uptake in normal thyroid tissue. Therefore, the aim of this study was to quantify the possible influence of this medication on intra-therapeutic radioiodine biokinetics. A cohort of 928 patients with STN undergoing RIUT and RIT was analysed. Patients were subdivided into 3 groups. Group T3: medication with T3 (n = 274), group T4: medication with T4 (n = 184) and group NM: no additional medication (n = 470). The T3 and T4 subgroups were further subdivided depending on the dose of thyroid hormone medication. In order to analyse the influence of thyroid hormone medication on individual intra-thyroidal biokinetics, the variance of the determined individual EHL between RIUT and RIT within the single groups and within the subgroups was investigated. EHL was significantly decreased between RIUT and RIT in the T3 and T4 subgroups (EHL: T3: 5.9 ± 1.1 d in RIUT and 3.3 ± 1.4 d in RIT (− 43%) (p < 0.05); T4: 5.9 ± 1.2 d in RIUT and 3.4 ± 1.5 d in RIT (− 42%) (p < 0.05). The decrease of EHL did not differ statistically between T3 or T4. However, both showed a highly significant difference compared to the NM group (p < < 0.05). A further subgroup analysis showed a significant dependence of the decrease in EHL related to the dose of thyroid hormone medication of 35–58% (T3) and 15–67% (T4) (p < 0.05). A significantly reduced EHL compared to RIUT in patients receiving thyroid hormone medication was detected. Moreover, a significant correlation between the dose of thyroid hormone medication (T3 or T4) and the decrease of EHL was found. Therefore, an adaption of the calculated activity should be considered in RIUT to obtain the required radiation dose in RIT of patients suffering from STN.

Retrospective Analysis of the Development of Human Thyroglobulin during Pregnancy in Patients with Treated Non-Recurrent Differentiated Thyroid Cancer

Aim: Therapy success in patients with differentiated thyroid cancer (DTC) after thyroidectomy and radioiodine therapy (RIT) is proven by permanent decrease in human thyroglobulin (hTg) to <1 ng/mL. In this retrospective analysis hTg development before, during and after pregnancy were analyzed. Material and methods: A descriptive analysis of hTg courses in 47 women with 57 pregnancies under levothyroxine substitution was performed after treatment of DTC without evidence of residual or recurrent disease. We compared hTg levels before, during and after pregnancies. A median of four measurements were performed during pregnancy. Results: In five out of the 47 patients at least one hTg increase to ≥1.0 ng/mL occurred during pregnancy (P1: 1.1; P2: 1.75; P3: 1.0; P4: 1.1; P5: 1.07 ng/mL). In another three cases an increase to ≥0.5 ng/mL occurred. After delivery, all patients returned to undetectable hTg levels. Human Tg maxima during pregnancy were significantly elevated according to Friedman´s Chi2 and p Holm−Bonferroni. Conclusion: In women with ablative thyroid therapy after DTC, a temporary elevation in hTg levels during pregnancy may occur. The reason therefore remains unclear and requires further investigation.

[Anticipating Criteria for Discharge after Lu-177-PSMA Treatment - Discussion of Several Scenarios]

AIM

The aim is to add a pragmatic contribution to the discussion of an algorithm to discharge patients treated with Lu-177-PSMA under the aspect of radiation protection. This also may be applied to therapies with other radioactive tracers in the future.

MATERIAL AND METHODS

478 cycles of Lu-177-PSMA-617 (140 patients) were analyzed. The remaining activity in the patient and the dose rate were correlated. From frequent intratherapeutic measurements (biexponential fit) scenarios for discharging patients are deduced.

RESULTS

Thirty-four per cent of all patients treated with Lu-177-PSMA received 3 to 5 cycles per calendar year. The dose limit of 1 mSv per calendar year (German Law) at a distance of 2 m from the patient would be exceeded in 10 % and 15 % of the treated patients if discharged 72 hours after treatment given 3 and 4 cycles per calendar year, respectively. Mean specific dose rate was 0.00462µSv/(h MBq) at a distance of 1 m. A universal correlation between dose rate and the remaining activity in the patient could not be found.

CONCLUSION

The multi cycle concept of the therapies with Lu-177 PSMA has to be taken into account prospectively when discharging the patients. Given the physical half-life of Lu-177 an anticipation of 4 treatment cycles per calendar year leads to a clearly arranged, conservative rule.

Focus on radioiodine-131 biokinetics: the influence of methylprednisolone on intratherapeutic effective half-life of 131I during radioiodine therapy of Graves' disease

AIM

Radioiodine therapy (RIT) may trigger the development of Graves' ophthalmopathy (GO) or exacerbate pre-existing subclinical GO. Therefore, glucocorticoid administration is recommended for patients with pre-existing GO. Aim of this study was to analyze the influence of glucocorticoid therapy with methylprednisolone on intratherapeutic effective half-life (EHL) of radioiodine-131 in patients with Graves' disease (GD) as recent studies showed an effect for prednisolone.

METHODS

In a retrospective study, 264 patients with GD who underwent RIT without any additional antithyroid medication were evaluated. Intrathyroidal EHL was determined pre- and intratherapeutically. Patients with co-existing GO (n = 43) received methylprednisolone according to a fixed scheme starting 1 day prior to RIT, patients without GO (n = 221) did not receive any protective glucocorticoid medication. The ratios of EHL during RIT and during radioiodine uptake test (RIUT) were compared.

RESULTS

Patients receiving methylprednisolone showed a slight decrease of the mean EHL from 5.63 d (RIUT) to 5.39 d (RIT) (p > 0.05). A comparable result was obtained in patients without glucocorticoids (5.71 d (RIUT) to 5.47 d (RIT); p > 0.05). The ratios of the EHL between RIT and RIUT failed to show a significant difference between the two groups. EHL is therefore not significantly influenced by an additional protective treatment with methylprednisolone.

CONCLUSIONS

In the present study a decreased intrathyroidal EHL under glucocorticoid medication with methylprednisolone could not be detected. Therefore, co-medication with methylprednisolone in patients with GO may be preferred to avoid an intratherapeutic decrease of EHL by accompanying protective glucocorticoides.

Radio-Iodide Treatment: From Molecular Aspects to the Clinical View

Simple Summary

This year marks the 80th commemoration of the first time that radio-iodide treatment (RAI) was used. RAI is one of the most effective targeted internal radiation anticancer therapies ever devised and it has been used for many decades, however, a thorough understanding of the underlying molecular mechanisms involved could greatly improve the success of this therapy. This is an in-depth innovative review focusing on the molecular mechanisms underlying radio-iodide therapy in thyroid cancer and how the alteration of these mechanisms affects the results in the clinic.

Abstract

Thyroid radio-iodide therapy (RAI) is one of the oldest known and used targeted therapies. In thyroid cancer, it has been used for more than eight decades and is still being used to improve thyroid tumor treatment to eliminate remnants after thyroid surgery, and tumor metastases. Knowledge at the molecular level of the genes/proteins involved in the process has led to improvements in therapy, both from the point of view of when, how much, and how to use the therapy according to tumor type. The effectiveness of this therapy has spread into other types of targeted therapies, and this has made sodium/iodide symporter (NIS) one of the favorite theragnostic tools. Here we focus on describing the molecular mechanisms involved in radio-iodide therapy and how the alteration of these mechanisms in thyroid tumor progression affects the diagnosis and results of therapy in the clinic. We analyze basic questions when facing treatment, such as: (1) how the incorporation of radioiodine in normal, tumor, and metastatic thyroid cells occurs and how it is regulated; (2) the pros and cons of thyroid hormonal deprivation vs. recombinant human Thyroid Stimulating Hormone (rhTSH) in radioiodine residence time, treatment efficacy, thyroglobulin levels and organification, and its influence on diagnostic imaging tests and metastasis treatment; and (3) the effect of stunning and the possible causes. We discuss the possible incorporation of massive sequencing data into clinical practice, and we conclude with a socioeconomical and clinical vision of the above aspects.