A Matter of Controversy: Is Radioiodine Therapy Favorable in Differentiated Thyroid Carcinoma?

Breast metastasis of papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer, and regional neck metastasis is more common than distant metastasis. If present, metastasis most frequently occurs in lungs and bones. Follicular variant of papillary thyroid carcinoma (FVPTC) is a mixture of the classic and follicular thyroid carcinoma and metastasizes in the same fashion as the PTC with cervical lymph nodes as the most common site. A case of atypical presentation of FVPTC with rib metastasis is reported. We present a case of an old man with a left-sided palpable breast mass for 2 months in duration without breast pain. Initially, the breast mass was categorised as Breast Imaging Reporting and Data System (BI-RADS) 4a via ultrasonography. Subsequent immunohistochemistry demonstrated that the mass was metastatic thyroid cancer. Consequently, a CT scan revealed a tumour originating from the rib. The patient was finally diagnosed with metastatic FVPTC.

Know thy tumour: Biomarkers to improve treatment of molecular radionuclide therapy

Molecular radionuclide therapy (MRT) is an effective treatment for both localised and disseminated tumours. Biomarkers can be used to identify potential subtypes of tumours that are known to respond better to standard MRT protocols. These enrolment-based biomarkers can further be used to develop dose-response relationships using image-based dosimetry within these defined subtypes. However, the biological identity of the cancers treated with MRT are commonly not well-defined, particularly for neuroendocrine neoplasms. The biological heterogeneity of such cancers has hindered the establishment of dose-responses and minimum tumour dose thresholds. Biomarkers could also be used to determine normal tissue MRT dose limits and permit greater injected doses of MRT in patients. An alternative approach is to understand the repair capacity limits of tumours using radiobiology-based biomarkers within and outside patient cohorts currently treated with MRT. It is hoped that by knowing more about tumours and how they respond to MRT, biomarkers can provide needed dimensionality to image-based biodosimetry to improve MRT with optimized protocols and personalised therapies.

Individualized treatment of differentiated thyroid cancer: The value of surgery in combination with radioiodine imaging and therapy - A German position paper from Surgery and Nuclear Medicine

A consensus statement about indications for post-surgical radioiodine therapy (RIT) in differentiated thyroid cancer patients (DTC) was recently published by the European Thyroid Association (ETA) 1. This publication discusses indications for RIT on the basis of an individual risk assessment. Many of the conclusions of this consensus statement are well founded and accepted across the disciplines involved. However, especially from the perspective of nuclear medicine, as the discipline responsible for indicating and executing RIT, some of the recommendations may require further clarification with regard to their compatibility with established best practice and national standards of care. Assessment of the indications for RIT is strongly dependent on the weighing up of benefits and risks. On the basis of longstanding clinical experience in nuclear medicine, RIT represents a highly specific precision medicine procedure of proven efficacy with a favorable side-effect profile. This distinguishes RIT significantly from other adjuvant oncological therapies and has resulted in the establishment of this procedure as a usually well-tolerated, standard safety measure. With regard to its favorable risk/benefit ratio, this procedure should not be unnecessarily restricted, in the interest of offering reassurance to the patients. Both patients' interests and regional/national differences need to be taken into account. We would therefore like to comment on the recent consensus from the perspective of authors and to provide recommendations based on the respective published data.

Incidence and Predictors of Synchronous Bone Metastasis in Newly Diagnosed Differentiated Thyroid Cancer: A Real-World Population-Based Study

Background

Clinical and sociodemographic characteristics of differentiated thyroid cancer (DTC) patients with synchronous bone metastasis (SBM) remain unclear. This real-world study aimed to elucidate the incidence and prognosis of DTC patients with SBM using population-based data.

Methods

Data of patients with newly diagnosed DTC from 2010 to 2016 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Multivariable logistic regression analysis was utilized to identify predictors of developing SBM in patients with DTC and was further evaluated by receiver operator characteristics (ROC) analysis. Multivariable Cox regression was applied to identify prognostic factors associated with overall survival (OS) and cancer-specific survival (CSS).

Results

A total of 67,176 patients with DTC were screened from the database, with 0.36% (244/67,176) developed SBM. The age-adjusted incidence of SBM in patients with DTC was relatively stable during the study period with an average annual percentage change (AAPC) of 2.52. Multivariable logistic regression analysis recognized seven factors (older age, male gender, black race, other races, follicular histology, the American Joint Committee on Cancer (AJCC) T2, T3, T4 staging, and N1 staging) as predictors of developing SBM among the entire cohort, with the value of area under the curve (AUC) of 0.931 (95% CI: 0.915–0.947). The median survival time of DTC patients with SBM was 22 months (interquartile range, 7–47 months). The multivariable Cox regression analysis indicated multiple metastatic sites, surgical procedures, and chemotherapy as predictors for the survival of patients.

Conclusions

Predictors and prognostic factors of SBM in patients with DTC were identified in this study. Patients with risk factors should be given more attention in clinical practice.

Variations in Radioiodine Therapy in Europe - Decision-Making after Total Thyroidectomy

The role of radioiodine therapy (RIT) (used as ablation therapy or adjuvant therapy) following total thyroidectomy for differentiated thyroid cancer (DTC) changed. Major revisions of the American Thyroid Association (ATA) Guidelines in 2015 resulted in significant differences in treatment recommendations in comparison to the European Association of Nuclear Medicine (EANM) 2008 guidelines. Recently, we presented the effects on daily practice for RIT among Swiss Nuclear Medicine centers. We now performed a study at the European level and hypothesized that there is also considerable variability among European experts. We performed a decision-tree based analysis of management strategies from all members of the EANM thyroid committee to map current practice among experts. We collected data on whether or not RIT is administered, on which criteria these decision are based, and collected details on treatment-activities and patient preparation. Our study shows discrepancies for low-risk DTC, where "follow-up only" is recommended by some experts while RIT with significant doses is used by other experts. E.g. for pT1b tumors without evidence of metastases the level of agreement for the use of RIT is as low as 50%. If RIT is administered, activities of I-131 range from 1.1 GBq to 3.0 GBq. In other constellations (e.g. pT1a) experts diverge from current clinical guidelines as up to 75% administer RIT in certain cases. For intermediate and high-risk patients, RIT is generally recommended. However, dosing and treatment preparation (rhTSH vs. THW) vary distinctly. In comparison to the Swiss study, the general level of agreement is higher among the European experts. The recently proposed approach on the use of RIT, based on integrated post-surgery assessment (Martinique paper) and results of ongoing prospective randomized studies are likely to reduce uncertainty in approaching RIT treatment. In certain constellations, consensus identified among European experts might be helpful in formulating future guidelines.

Inability of Radioiodine Remnant Ablation to Improve Postoperative Outcome in Adult Patients with Low-Risk Papillary Thyroid Carcinoma

OBJECTIVE

To determine whether radioiodine remnant ablation (RRA) reduces cause-specific mortality (CSM) or tumor recurrence (TR) rate after bilateral lobar resection (BLR).

PATIENTS AND METHODS

There were 2952 low-risk adult papillary thyroid cancer (LRAPTC) patients (with MACIS scores <6) who underwent potentially curative BLR during 1955-2014. During 1955-1974, 1975-1994, and 1995-2014, RRA was administered in 3%, 49%, and 28%. Statistical analyses were performed using SAS software.

RESULTS

During 1955-1974, the 20-year CSM and TR rates after BLR alone were 1.0% and 6.8%; rates after BLR+RRA were 0% (P=.63) and 5.9% (P=.82). During 1975-1994, post-BLR 20-year rates for CSM and TR were 0.3% and 7.5%; after BLR+RRA, rates were higher at 0.9% (P=.31) and 12.8% (P=.01). When TR rates were examined separately for 448 node-negative and 317 node-positive patients, differences were nonsignificant. In 1995-2014, post-BLR 20-year CSM and TR rates were 0% and 9.2%; rates after BLR+RRA were higher at 1.4% (P=.19) and 21.0% (P<.001). In 890 pN0 cases, 15-year locoregional recurrence rates were 3.4% after BLR and 3.7% after BLR+RRA (P=.99). In 740 pN1 patients, 15-year locoregional recurrence rates were 10% higher after BLR+RRA compared with BLR alone (P=.01). However, this difference became nonsignificant when stratified by numbers of metastatic nodes.

CONCLUSION

RRA administered to LRAPTC patients during 1955-2014 did not reduce either the CSM or TR rate. We would therefore not recommend RRA in LRAPTC patients undergoing BLR with curative intent.

Radioiodine therapy reduces the frequency of circulating tumour cells in patients with differentiated thyroid cancer

OBJECTIVE

The aim of the study was the quantification of circulating tumour cells (CTCs) in differentiated thyroid cancer (DTC) patients before and 6 weeks after radioiodine therapy (RIT).

CONTEXT

Circulating tumour cells (CTCs) were described more recently in cancer patients, mostly correlating with poor outcome and advanced metastases.

DESIGN

Peripheral blood for identification and quantification of CTC before RIT or/and 6 weeks after RIT was provided by 55 DTC patients that received RIT for remnant tissue ablation.

PATIENTS

13 follicular thyroid cancer (FTC) patients, 31 papillary thyroid cancer (PTC) patients and 11 patients having the follicular variant PTC (FV-PTC) were included.

MEASUREMENTS

Peripheral blood mononuclear cells (PBMCs) were isolated and EpCAM-positive CTCs were counted by immune fluorescent staining.

RESULTS

A CTC positivity of 31.8% before RIT could be observed. Six weeks after RIT, the CTC positivity was reduced to 13.6%. Paired data at both time points of blood sampling could be gathered for n = 33 DTC patients. These patients had significantly higher CTC numbers before RIT than 6 weeks afterwards (0.27 ± 0.47 vs 0.05 ± 0.15, P = .0215). Additionally, significantly reduced CTC numbers were also demonstrated in pre-RIT CTC-positive patients (0.88 ± 0.43 vs 0.05 ± 0.16, P = .0039).

CONCLUSION

Our results indicate a reducing effect on the number of CTCs by RIT. Therefore, CTC enumeration should be considered as efficient tool for treatment monitoring during RIT.

Radioiodine in Differentiated Thyroid Carcinoma: Do We Need Diagnostic Pre-Ablation Iodine-123 Scintigraphy to Optimize Treatment?

Changing insights regarding radioiodine (I-131) administration in differentiated thyroid carcinoma (DTC) stir up discussions on the utility of pre-ablation diagnostic scintigraphy (DxWBS). Our retrospective study qualitatively and semi-quantitatively assessed posttherapy I-131 whole-body scintigraphy (TxWBS) data for thyroid remnant size and metastasis. Findings were associated with initial treatment success after nine months, as well as clinical, histopathological, and surgical parameters. Possible management changes were addressed. A thyroid remnant was reported in 89 of 97 (92%) patients, suspicion of lymph node metastasis in 26 (27%) and distant metastasis in 6 (6%). Surgery with oncological intent and surgery by two dedicated thyroid surgeons were independently associated with a smaller remnant. Surgery at a community hospital, aggressive tumor histopathology, histopathological lymph node metastasis (pN1) and suspicion of new lymph node metastasis on TxWBS were independently associated with an unsuccessful treatment. Thyroid remnant size was unrelated to treatment success. All 13 pN1 patients with suspected in situ lymph node metastases on TxWBS had an unsuccessful treatment, opposite 19/31 (61%) pN1 patients without (p = 0.009). Pre-ablative knowledge of these TxWBS findings had likely influenced management in 48 (50%) patients. Additional pre-ablative diagnostics could optimize patient-tailored I-131 administration. DxWBS should be considered, especially in patients with pN1 stage or suspected in situ lymph node metastasis. Dependent on local surgical expertise, DxWBS is not recommended to evaluate thyroid remnant size.

LINC00893 inhibits papillary thyroid cancer by suppressing AKT pathway via stabilizing PTEN

Long non-coding RNAs (lncRNAs) are important to the occurrence and advancement of human cancers. We found through GEPIA that LINC00893 was lowly expressed in thyroid carcinoma (THCA) tissues, whereas the specific functions of LINC00893 has never been reported in PTC. In the current study, we confirmed that LINC00893 was expressed at a low level in PTC cells. Through gain-of-function assays, we determined that LINC00893 overexpression abrogated proliferation and migration abilities of PTC cells. Through signal transduction reporter array we found that LINC00893 potentially modulated the signals of phosphatase and tensin homolog (PTEN)/AKT pathway. In addition, overexpression of LINC00893 increased the expression of PTEN but reduced the levels of phosphorylated AKT in PTC. Additionally, mechanism assays unveiled that LINC00893 stabilized PTEN mRNA via recruiting Fused in sarcoma (FUS) protein. Finally, rescue assays demonstrated that LINC00893 hampered the proliferation and migration of PTC cells via PTEN/AKT pathway. Together, our study first clarified that LINC00893 functions as a tumor suppressor in PTC by blocking AKT pathway through PTEN upregulation.

Changes in Population-Level and Institutional-Level Prescribing Habits of Radioiodine Therapy for Papillary Thyroid Cancer

Background: In the past two decades, new evidence and guidelines have emerged to refine recommendations for the use of radioactive iodine (RAI) therapy after thyroidectomy for cancer. We aim to describe national trends in RAI utilization, assess the impact of individual hospitals on RAI utilization, and examine whether variation in prescribing habits has declined over time. Methods: The National Cancer Database (NCDB) was queried from 2004 to 2016 for patients with papillary thyroid cancer (PTC) who received total thyroidectomy. Trends were analyzed using Joinpoint analysis. Hospital-specific effects and variation in prescribing habits were assessed through a hierarchical, mixed regression model. Results: RAI utilization declined from 61.0% in 2004 to 43.9% in 2016. RAI use declined most profoundly in patients with T1a, N0/X, M0 PTC without extrathyroidal extension (34.8% in 2004 to 9.5% in 2015), but continues to be used commonly in patients with advanced disease for whom it is routinely recommended (73.4% in 2004 to 72.0% in 2015). Furthermore, ∼80% of hospitals in 2016 utilized at or below the median utilization rate in 2006. Variation in RAI utilization across hospitals decreased by ∼50% from 2004 to 2016 (Levene's test p < 0.001), with a significant decline (p = 0.002) in the variation after 2012 (confidence interval: 2010 to 2014). Conclusions: Recommendations for whom to prescribe RAI appear to have impacted both the number of patients receiving RAI and the variation in prescribing habits across hospitals. Hospital selection has contributed less to the probability of receiving RAI over time.

Controversies in Radioiodine Treatment of Low- and Intermediate-risk Thyroid Cancer

In differentiated thyroid cancer, radioiodine therapy (RIT) is usually carried out after thyroidectomy. Although the potent beneficial effects of radioiodine are undisputed in high-risk patients, much controversy remains surrounding many aspects of RIT in low- and intermediate-risk patients. Other than the indication for postoperative RIT, controversies also include, among others, the intent of RIT and the choice of activity for RIT or the mode of thyroid stimulating hormone stimulation. Furthermore, there is even controversy on the definition of what constitutes low- or intermediate-risk patients. Here the various issues will be discussed and an overview of the different points of view in a number of more prominent national and international guidelines and current literature is presented.

The effects of radioiodine therapy on parathyroid function among patients with papillary thyroid cancer: a retrospective cohort study

PURPOSE

To explore the effects of initial radioiodine therapy on parathyroid function among postoperative papillary thyroid cancer (PTC) patients.

METHODS

Postoperative PTC patients who were admitted in our department from April 2018 to April 2019 were recruited. Patients were divided into two groups: Group A, who underwent surgery and initial radioiodine therapy in our hospital, and Group B, who did not receive radioiodine therapy after surgery. The levels of serum calcium, magnesium, phosphorus, parathyroid hormone (PTH), and 25 hydroxyvitamin D3 were collected. Data were analyzed by SPSS 25.0.

RESULTS

A total of 252 patients were included. Between the two groups, no significant difference of PTH in 6th, 9th, and 12th month was found during postoperative follow-up (p = 0.493, p = 0.202, p = 0.814). No significant difference of PTH was found after stratifying Group A according to ¹³¹I dosage (p = 0.751 for 6th month after operation, p = 0.130 for 9th month after operation, p = 0.683 for 12th month after operation), interval time between surgery and radioiodine therapy (p = 0.522 for 3rd day after ¹³¹I therapy, p = 0.184 for 9th month after operation, p = 0.311 for 12th month after operation), and ratio of parathyroid autotransplantation (p = 0.545 for 3rd day after ¹³¹I therapy, p = 0.485 for 6th month after operation, p = 0.201 for 9th month after operation, p = 0.146 for 12th month after operation).

CONCLUSIONS

Initial radioiodine therapy following PTC surgery had no significant adverse effect on parathyroid function in the short term. However, physicians should inform patients of possible risks of abnormal parathyroid function prior to RAI therapy, and parathyroid function was periodically reviewed after RAI therapy.

Variations in radioiodine ablation: decision-making after total thyroidectomy

BACKGROUND

The role of radioiodine treatment following total thyroidectomy for differentiated thyroid cancer is changing. The last major revision of the American Thyroid Association (ATA) Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer in 2015 changed treatment recommendations dramatically in comparison with the European Association of Nuclear Medicine (EANM) 2008 guidelines. We hypothesised that there is marked variability between the different treatment regimens used today.

METHODS

We analysed decision-making in all Swiss hospitals offering radioiodine treatment to map current practice within the community and identify consensus and discrepancies. RESULTS AND CONCLUSION: We demonstrated that for low-risk DTC patients after thyroidectomy, some institutions offered only follow-up, while RIT with significant activities is recommended in others. For intermediate- and high-risk patients, radioiodine treatment is generally recommended. Dosing and treatment preparation (recombinant human thyroid stimulation hormone (rhTSH) vs. thyroid hormone withdrawal (THW)) vary significantly among centres.

Radioiodine treatment of differentiated thyroid cancer related to guidelines and scientific literature

In differentiated thyroid cancer (DTC), radioiodine is administered to eliminate residual normal thyroid tissue after thyroidectomy (ablative treatment), to treat residual microscopic disease (adjuvant treatment), and to treat macroscopic or metastatic disease. Currently, treatment of DTC with ¹³¹I is still a matter of controversy due to the absence of prospective clinical trials assessing its benefit in terms of overall survival and recurrence-free interval. The current recommendations of the experts are based on observational retrospective data and on their interpretation of the literature. Pending the results of the prospective trials that are currently underway, the use of ¹³¹I seems to be justified not only in high-risk patients, but also in intermediate-risk and low-risk patients. The guidelines of The American and British Thyroid Association, European and American Societies of Nuclear Medicine, The European Consensus Group and the latest edition of National Comprehensive Cancer Network (NCCN) were considered in drawing up this continuing education document, we also undertook a review of the related scientific literature.