Value of stimulated pre-ablation thyroglobulin as a prognostic marker in patients with differentiated thyroid carcinoma treated with radioiodine

Retrospective case-control study examining the relationship between recurrence-free survival and changes in pre- and post-radioiodine therapy serum thyroglobulin levels in patients with differentiated thyroid cancer

PURPOSE

Thyroglobulin assay is important to assess the residual or recurrence of differentiated thyroid cancer (DTC). Patients with positive serum thyroglobulin levels after radioactive iodine (RAI) adjuvant therapy could achieve long-term recurrence-free survival (RFS). The patient's prognosis could not be confidently estimated based solely on the evaluation of thyroglobulin levels. We investigated the recurrence rate and RFS of patients who received adjuvant RAI therapy after surgery for DTC to clarify the relationship between changes in pre- and post-therapy serum thyroglobulin levels and RFS.

MATERIALS AND METHODS

Patients who underwent adjuvant RAI therapy between May 2007 and March 2021 were included in this study, whereas those with positive anti-thyroglobulin antibodies, distant metastases, or gross residual tumors were excluded. The change in pre- and post-treatment serum thyroglobulin levels under thyroid-stimulating hormone stimulation was calculated and classified as follows: group A, thyroglobulin levels decreased by ˃10%; group B, thyroglobulin levels within a range of 10% or less; and group C, thyroglobulin levels increased by ˃10%. RFS outcomes were analyzed using the Kaplan-Meier method. Univariate analysis was performed using the log-rank test, and multivariate analysis was performed using the Cox proportional hazard model.

RESULTS

A total of 74 patients were included. Relapse was seen in 13 of 46 patients in group A, 9 of 15 in group B, and 10 of 13 in group C. Median RFS was 129.00 (95% confidence interval CI 77.79-180.21), 113.00 (95% CI 86.83-139.17), and 33 months (95% CI 6.026-59.974) in groups A, B, and C, respectively. Patients in group C exhibited significantly shorter RFS than those in groups A and B (P = 0.001).

CONCLUSIONS

Changes in thyroglobulin levels pre- and post-therapy were associated with RFS. Patients with decreased post-therapy thyroglobulin levels had a favorable prognosis, even if their thyroglobulin levels were positive after RAI therapy.

Metastatic differentiated thyroid cancer with negative serum stimulated Tg but positive post-therapeutic 131I-SPECT/CT scintigraphy: a single-center retrospective study

PURPOSE

This study aimed to describe the characteristics of patients with metastatic differentiated thyroid carcinoma (DTC) who had positive 131I-scintigraphy but negative stimulated thyroglobulin (sTg), and to evaluate their short-term response to radioiodine therapy (RAI).

METHODS

A total of 2250 consecutive postoperative DTC patients, who underwent RAI treatment from July 2019 to June 2022, were analyzed retrospectively. The target group was defined as stimulated Tg < 2 ng/mL with TgAb < 100 IU/mL but with post-therapeutic 131I-SPECT/CT metastases. The characteristics of these patients were analyzed and the metastatic profiles were compared with TgAb positive or sTg positive ones. A cross-sectional efficacy was evaluated 6-12 months after the RAI therapy and the treatment course until the end of the study was recorded.

RESULTS

105 (4.67%) DTC patients were post-therapeutic 131I-SPECT/CT positive and sTg negative (target group). Metastatic profiles were found significant differences between sTg negative and sTg positive ones (P < 0.001). Excellent response (ER) was achieved in 72.4% of the target group between 6-12 months of cross-sectional efficacy assessment, compared with only 12.8% in sTg positive ones (P < 0.001). The majority of the target group didn't require aggressive treatment in short-term follow-up compared with sTg positive group (P < 0.001).

CONCLUSION

The percentage of DTCs with negative sTg but positive post-therapeutic 131I-SPECT/CT was relatively low, but still significant. Moreover, the majority of these patients showed an ER to RAI and may not require the next course of therapy. Long-term follow-up is still necessary to assess recurrence and adapt surveillance in these patients.

Initial results of the INSPIRE clinical trial-investigating radiation dosimetry for differentiated thyroid cancer patients

Introduction

The optimal strategy for differentiated thyroid cancer (DTC) patients treated with radioiodine (RAI) following thyroidectomy remains controversial. Multi-centre clinical studies are essential to identify strategies to improve patient outcomes while minimising treatment-induced toxicity.

Materials and Methods

The INSPIRE clinical trial (ClinicalTrials.gov Identifier: NCT04391244) aims to investigate patient-specific dosimetry for DTC patients and to determine the range of absorbed doses delivered to target and non-target tissues and their relationship with treatment outcome and toxicity.

Results

We report here initial results of the first 30 patients enrolled onto the INSPIRE trial. A large range of absorbed doses are observed for both thyroid remnants and salivary glands, with median values of 4.8 Gy (Range 0.2 - 242 Gy) and 0.3 Gy (Range 0.1 to 1.7 Gy), respectively.

Discussion

The preliminary study results are encouraging and could help to improve our understanding of absorbed doses to thyroid remnants and normal organs following RAI therapy. Such knowledge could potentially enable patient-specific treatment planning with improved clinical outcomes and quality-of-life of patients.

Comparing the efficacy of thyroglobulin and thyroglobulin/ thyroid-stimulating hormone ratio models in predicting a successful response to radioactive iodine therapy

BACKGROUND

The thyroglobulin (Tg)/ thyroid-stimulating hormone (TSH) ratio has manifested to be a reliable marker for predicting prognosis in patients with differentiated thyroid carcinoma (DTC). The objective of this study was to compare the efficacy of Tg and Tg/TSH ratio models in predicting a successful response to radioactive iodine therapy.

METHODS

One thousand six hundred forty-two DTC patients receiving ¹³¹I radiotherapy were finally enrolled in this retrospective study. The patients were divided into a training set (n = 973) and a validation set (n = 669) by the patient consultation time (July 2019). A receiver-operating characteristic curve was constructed for Tg and the Tg/TSH ratio to establish their cutoffs. Then, the variables were screened by univariate logistic regression and incorporated into logistic prediction models by stepwise regression, where Tg/TSH was excluded from model 1 and Tg was excluded from model 2.

RESULTS

In 1642 enrolled DTC patients, the first ¹³¹I radiotherapy had an excellent response in 855 patients. The cut-offs for Tg level and Tg/TSH ratio were 3.40 ng/ mL [area under the curve (AUC): 0.789] and 36.03 ng/mIU (AUC: 0.788), respectively. In addition, the AUC of the model including Tg was higher than that of the model including Tg/TSH in both the training set (0.837 vs 0.833) and the testing set (0.854 vs 0.836).

CONCLUSIONS

Both Tg and Tg/TSH ratios could be considered predictors of the effects of the first ¹³¹I ablative therapy. However, the prediction model including Tg performed better than the model including Tg/TSH.

Differential distribution and prognostic value of CD4+ T cell subsets before and after radioactive iodine therapy in differentiated thyroid cancer with varied curative outcomes

Differentiated thyroid cancer is the most frequently diagnosed endocrine tumor. While differentiated thyroid cancers often respond to initial treatment, little is known about the differences in circulating immune cells amongst patients who respond differently. A prospective study of 39 patients with differentiated thyroid cancer was conducted. Serum thyroglobulin levels and thyroid and immunological functions were tested before and after radioactive iodine treatment (RAIT). Efficacy assessments were performed 6 to 12 months after radioactive iodine treatment. Most patients showed an excellent response to radioactive iodine treatment. Before radioactive iodine treatment, the excellent response group had considerably fewer circulating CD4⁺ T cell subsets than the non-excellent response group. Both the excellent response and non-excellent response groups had considerably lower circulating CD4⁺ T lymphocyte subsets 30 days after radioactive iodine treatment, but those of the excellent response group were still lower than those of the non-excellent response group. All circulating CD4⁺ T cell subsets in the excellent response group rose by varying degrees by the 90th day, but only Treg cell amounts increased in the non-excellent response group. Interestingly, in the non-excellent response group, we noticed a steady drop in Th1 cells. However, the bulk of circulating CD4⁺ T cell subsets between the two groups did not differ appreciably by the 90th day. Finally, we discovered that CD4⁺ T cell subsets had strong predictive potential, and we thus developed high-predictive-performance models that deliver more dependable prognostic information. In conclusion, in individuals with differentiated thyroid cancer, there is great variation in circulating immune cells, resulting in distinct treatment outcomes. Low absolute CD4⁺ T cell counts is linked to improved clinical outcomes as well as stronger adaptive and resilience capacities.