Guidelines for radioiodine therapy of differentiated thyroid cancer

Analysis of Residence Time, Effective Half-Life, and Internal Dosimetry Before Radioiodine Therapy

Radioiodine therapy has been widely used for ablation of remnant tissue after surgical treatment of differentiated thyroid carcinoma (DTC). Internal dosimetry provides a new approach to choosing the administered activity-an approach that considers the distribution and retention of 131I individually per patient. This study used clinical techniques of internal dosimetry to assess the accumulated activity, internal bone marrow dosimetry, and effective half-life in patients undergoing treatment for DTC. Methods: This was a quantitative, retrospective study analyzing diagnostic documents and images. The internal dosimetry method calculated the dose absorbed by the bone marrow per administered activity of 131I. Calculation of the absorbed dose took into account the accumulated activity, which was obtained through measurements of whole-body images acquired at 4 intervals over 5 d. Results: The median dose absorbed by the bone marrow per administered activity was 0.117 mGy/MBq (range, 0.043-0.152 mGy/MBq). The median whole-body residence time was 22.0 h (range, 12.6-39.4 h). The median effective half-life was 15.6 h (range, 7.6-28.2 h). Conclusion: Internal dosimetry provides information relevant to safe dose limits for DTC radioiodine therapy, especially in advanced cases of the disease for which greater activities may be necessary.

Initial Testing of an Approximated, Fast Calculation Procedure for Personalized Dosimetry in Radionuclide Therapy Based on Planar Whole-Body Scan and Monte-Carlo Specific Dose Rates from the OpenDose Project

Individualized dosimetry in nuclear medicine is currently at least advisable in order to obtain the best risk–benefit balance in terms of the maximal dose to lesions and under-threshold doses to radiosensitive organs. This article aims to propose a procedure for fast dosimetric calculations based on planar whole-body scintigraphy (WBS) images and developed to be employed in everyday clinical practice. Methods: For simplicity and legacy reasons, the method is based on planar imaging dosimetry, complemented with some assumptions on the radiopharmaceutical kinetics empirically derived from single-photon emission tomography/computed tomography (SPECT/CT) image analysis. The idea is to exploit a rough estimate of the time-integrated activity as has been suggested for SPECT/CT dosimetry but using planar images. The resulting further reduction in dose estimation accuracy is moderated by the use of a high-precision Monte-Carlo S-factor, such as those available within the OpenDose project. Results: We moved the problem of individualized dosimetry to a transformed space where comparing doses was imparted to the ICRP Average Male/Female computational phantom, resulting from an activity distribution related to patient’s pharmaceutical uptake. This is a fast method for the personalized dosimetric evaluation of radionuclide therapy, bearing in mind that the resulting doses are meaningful in comparison with thresholds calculated in the same framework. Conclusion: The simplified scheme proposed here can help the community, or even the single physician, establish a quantitative guide-for-the-eye approach to individualized dosimetry.

Radionuclides for Targeted Therapy: Physical Properties

A search in PubMed revealed that 72 radionuclides have been considered for molecular or functional targeted radionuclide therapy. As radionuclide therapies increase in number and variations, it is important to understand the role of the radionuclide and the various characteristics that can render it either useful or useless. This review focuses on the physical characteristics of radionuclides that are relevant for radionuclide therapy, such as linear energy transfer, relative biological effectiveness, range, half-life, imaging properties, and radiation protection considerations. All these properties vary considerably between radionuclides and can be optimised for specific targets. Properties that are advantageous for some applications can sometimes be drawbacks for others; for instance, radionuclides that enable easy imaging can introduce more radiation protection concerns than others. Similarly, a long radiation range is beneficial in targets with heterogeneous uptake, but it also increases the radiation dose to tissues surrounding the target, and, hence, a shorter range is likely more beneficial with homogeneous uptake. While one cannot select a collection of characteristics as each radionuclide comes with an unchangeable set, all the 72 radionuclides investigated for therapy-and many more that have not yet been investigated-provide numerous sets to choose between.

Personalized Dosimetry in the Context of Radioiodine Therapy for Differentiated Thyroid Cancer

The most frequent thyroid cancer is Differentiated Thyroid Cancer (DTC) representing more than 95% of cases. A suitable choice for the treatment of DTC is the systemic administration of 131-sodium or potassium iodide. It is an effective tool used for the irradiation of thyroid remnants, microscopic DTC, other nonresectable or incompletely resectable DTC, or all the cited purposes. Dosimetry represents a valid tool that permits a tailored therapy to be obtained, sparing healthy tissue and so minimizing potential damages to at-risk organs. Absorbed dose represents a reliable indicator of biological response due to its correlation to tissue irradiation effects. The present paper aims to focus attention on iodine therapy for DTC treatment and has developed due to the urgent need for standardization in procedures, since no unique approaches are available. This review aims to summarize new proposals for a dosimetry-based therapy and so explore new alternatives that could provide the possibility to achieve more tailored therapies, minimizing the possible side effects of radioiodine therapy for Differentiated Thyroid Cancer.

Second primary malignancies induced by radioactive iodine treatment of differentiated thyroid carcinoma - a critical review and evaluation of the existing evidence

PURPOSE

Concern is growing about long-term side effects of differentiated thyroid cancer treatment, most notably radioactive iodine (RAI) therapy. However, published studies on the subject have had heterogeneous cohorts and conflicting results. This review seeks to provide an updated evaluation of published evidence, and to elucidate the risk of second primary malignancies (SPMs), especially secondary hematologic malignancies (SHMs), attributable to RAI therapy.

METHODS

An extensive literature search was performed in Ovid MEDLINE, Ovid MEDLINE and In-Process & Other Non-Indexed Citations, Ovid MEDLINE Epub Ahead of Print, Cochrane Central Register of Controlled Trials (CENTRAL) and PubMed. Studies regarding RAI-induced SPMs or a dose-response relationship between RAI therapy and SPMs were identified, 10 of which were eligible for the analysis. We evaluated risk of bias in each study and judged quality of evidence (QOE) across all studies using the Grading of Recommendations, Assessment, Development and Evaluations approach.

RESULTS

For the outcome "SPM", the relative effect (relative risk, hazard ratio, or odds ratio) of RAI vs. no RAI ranged from 1.14 to 1.84 across studies, but most results were not statistically significant. For the outcome "SHM", reported relative effects ranged from 1.30 to 2.50, with 2/3 of the studies presenting statistically significant results. In 7/8 of the studies, increased risk for SPM was shown with increasing cumulative RAI activity. QOE was "very low" regarding SPM after RAI and regarding a dose-response relationship, and "low" for SHM after RAI.

CONCLUSION

Based on low quality evidence, an excess risk for the development of SPM cannot be excluded but is expected to be small.

[Therapy concepts for thyroid carcinoma]

Theranostics via the sodium iodide symporter (NIS) offer a unique option in differentiated thyroid carcinoma. The diagnostic and therapeutic nuclides have similar uptake and kinetics, making the NIS the most important theranostic target in this disease. Radioiodine refractory thyroid carcinomas (RRTC) are characterised by reduced/absent NIS expression, thus eliminating this structure as a theranostic target. Also due to limited therapeutic options, there are approaches to generate new theranostic targets in RRTC, via the expression of somatostatin receptors (SSTR) or the prostate-specific membrane antigen (PSMA), but the current evidence does not yet allow a final evaluation of the prospects of success.

Analysis of the Correlation between the Radioactive Iodine Activity and Neutrophil-to-Lymphocyte Ratio in Patients with Differentiated Thyroid Cancer

Publications investigating the effect of radioactive iodine (131I) therapy on the circulating peripheral blood cells in patients with differentiated thyroid cancer (DTC) are limited to blood samples collected more than 92 h after 131I. Studies conducted on blood samples collected up to 92 h are rare due to the radioactive contamination risk. This research aimed to assess the relationship between the prescribed 131I activity, human whole blood activity, and peripheral blood cells at many time points (6, 22, 46, 69, and 92 h after 131I). The study enrolled 50 female patients with DTC who received a 131I median activity of 90.54 mCi (3.35 GBq). The neutrophil-to-lymphocyte ratio (NLR) was measured as an inflammatory marker. 131I uptake in the residual thyroid tissue peaked after 46 h. Blood activity decreased in the first 46 h and increased 69 h after the 131I intake. Blood activity was associated with the absolute lymphocyte count and the NLR at 69 h (r = −0.49 and r = 0.52, p < 0.001). Our results demonstrate that the time interval between 46 and 69 h should be associated with the release of hematological inflammatory mediators, such as neutrophils and lymphocytes, to eradicate tumor cells in response to 131I therapy.

Is there an added value for whole body scan combined with stimulated thyroglobulin testing for follow-up of differentiated thyroid cancer patients?

BACKGROUND

Whole-body scan (WBS) is indicated for selected patients in the follow-up of differentiated thyroid cancer (DTC).

AIM

The aim of this study was to evaluate the incidence of positive WBS in patients with negative stimulated thyroglobulin (sTg), to define the clinical characteristics of this group, and the association with disease outcome.

METHODS

DTC patients who underwent surveillance with simultaneous sTg and WBS were included.

RESULTS

Two hundred seventy-two patients were included. Age at diagnosis was 46.5 ± 15.2 years, 79% were female. Mean duration of follow-up was 11.6 ± 6.8 years. Patients were categorised according to stimulation test results: sTg(-)/WBS(-) in 192/272 (70.6%); sTg(+) regardless of WBS results in 33/272 (12.1%); and sTg(-)/WBS(+) in 47/272 (17.3%) subjects. sTg > 10 mg/dl was considered positive. The three groups had similar demographic and pathologic characteristics. During follow-up, additional treatment was given in 77 patients (28.3%). Twelve (4.4%) developed distant metastases; 16 patients (5.8%) died. No deaths were disease-related. There was no difference in mortality rate between categories (P = 0.182). On multivariate analysis, additional treatment was associated with male gender (P = 0.046) and positive stimulation test results, either sTg (P < 0.001) or WBS (P < 0.001). Of the 47 WBS(+)/sTg(-) patients, 7(15%) were treated due to positive WBS results, including two who underwent additional surgery.

CONCLUSION

A substantial proportion of stimulation test results were discordant. There was a significant association between WBS results and administration of additional treatment. Routine WBS had additional value for a small proportion of patients with no other evidence for disease and no indication for WBS.

Could urinary iodine be an effective predictive factor for thyroid cancer after high dose radioactive iodine therapy?

OBJECTIVE

The present study was to investigate the possibility of using the results of UIC and UICR measurement as a marker for the curative effect of radioactive iodine (RAI) therapy.

METHODS

A total of 337 patients who underwent RAI therapy from May 2018 and March 2020 were recruited. According to levels of UIC or UICR, patients were divided into six groups: [A] UIC levels <100 μg/L; [B] 100 μg/L ≤ UIC levels < 200 μg/L; [C] UIC levels ≥ 200 μg/L; [D] UICR level <100 μg/g; [E] 100 μg/g ≤ UICR levels < 200 μg/g; [F] UICR levels ≥ 200 μg/g. Treatment and follow-up were defined according to criteria used in the 2015 ATA guidelines.

RESULTS

When dividing the 337 patients into 3 groups according to UIC levels, the A, B, C group were found in 50.7%, 22.6%, 26.7%, respectively. Based on UICR levels, the D, E, F group were identified in 58.1%, 29.4%, 12.5%. A significant positive correlation was demonstrated between UIC and UICR values and I-131 uptake rates (P<0.001). The ER rate also not significantly different between each group (P=0.997, P=0.634). In logistic regression analysis, UIC and UICR levels were not confirmed to be independent factors predicting the excellent response status, but age ≥ 55 year (OR=0.373, P=0.007); Tg levels ≥ 10 ng/mL (OR=18.972, P=0.001) were confirmed to be independent factors predicting the ER status at the end of follow-up.

CONCLUSIONS

The UIC or UICR levels before RAI therapy did not compromise the therapeutic response to I-131.

Prognostic factors in children and adolescents with differentiated thyroid carcinoma treated with total thyroidectomy and RAI: a real-life multicentric study

PURPOSE

This multicentric study aimed to investigate the main prognostic factors associated with treatment response at 1 year after radioactive iodine therapy (RAIT) and the last disease status in pediatric patients affected by differentiated thyroid carcinoma (DTC).

MATERIALS AND METHODS

In the period 1990-2020, all consecutive patients ≤ 18 years from six different centers were retrospectively included. Patients were classified as low, intermediate, and high risk for persistence/recurrence. The response to RAIT was evaluated and scored 1 year later according to 2015 ATA guidelines. Moreover, at the last follow-up, the disease status was evaluated and dichotomized as no evidence of disease (NED) or persistent disease.

RESULTS

Two hundred and eighty-five patients (197 female, 88 male; mean age 14.4 years) were recruited. All, except nine, underwent near-total thyroidectomy followed by RAIT. One-year after first RAIT, 146/276 (53%) patients had excellent response, 37/276 (14%) indeterminate response, and 91/276 (33%) incomplete response. One-year after RAIT, children with excellent response had significantly lower stimulated thyroglobulin (sTg) compared to not excellent group (median sTg 4.4 ng/ml vs 52.5 ng/ml, p < 0.001). ROC curve showed sTg higher than 27.2 ng/ml as the most accurate to predict 1-year treatment response. After a median follow-up of 133 months, NED was present in 241 cases (87%) while persistent disease in 35 (13%). At multivariate analysis, sTg and 1-year treatment response categories were both significantly associated with the last disease status (p value 0.023 and < 0.001).

CONCLUSIONS

In pediatric DTC, sTg is significantly associated with 1-year treatment response and final outcome. However, 1-year response is the principal prognostic factor able to predict pediatric DTCs outcome.

Psycho-Oncological Intervention Through Counseling in Patients With Differentiated Thyroid Cancer in Treatment With Radioiodine (COUNTHY, NCT05054634): A Non-randomized Controlled Study

Background

Diagnosis and treatment of differentiated thyroid carcinomas (DTC) cause anxiety and depression. Additionally, these patients suffer hormonal alterations that are associated with psychological symptoms (e.g., changes in mood, emotional instability, and memory loss). This study aims to evaluate the effectiveness of a psycho-oncological intervention based on counseling to reduce anxiety and depression related to the treatment in patients with DTC.

Methods

A non-randomized controlled study, with two groups [experimental group (EG), n = 37, and control group (CG), n = 38] and baseline and posttreatment measures, was designed. Patients in the EG received a psycho-oncological intervention based on counseling in addition to the standard treatment. The independent variable was the assigned group and the dependent one was the evolution of anxiety and depression, which were analyzed separately, and both were evaluated using the Hospital Anxiety and Depression Scale. Other relevant covariables related to the quality of life (QoL) were also analyzed using Short Form-36 Health Survey and Psychological General Wellbeing Index scales.

Results

The difference of the posttreatment-baseline variation showed a statistically significant reduction in anxiety and depression in the EG in relation to the CG (p &lt; 0.001). The mean of the Psychological General Wellbeing Index scales score increased significantly in the EG (p &lt; 0.001) and decreased significantly in the CG (p &lt; 0.001). All the baseline and the posttreatment scores of the variables evaluated showed a statistically significant improvement in the EG vs. the CG.

Conclusion

This study demonstrates significant benefits of psycho-oncological intervention based on counseling in anxiety, depression, QoL, and wellbeing of the patient with differentiated thyroid carcinomas.

Comparison between Two Different Scanners for the Evaluation of the Role of 18F-FDG PET/CT Semiquantitative Parameters and Radiomics Features in the Prediction of Final Diagnosis of Thyroid Incidentalomas

The aim of this study was to compare two different tomographs for the evaluation of the role of semiquantitative PET/CT parameters and radiomics features (RF) in the prediction of thyroid incidentalomas (TIs) at ¹⁸F-FDG imaging. A total of 221 patients with the presence of TIs were retrospectively included. After volumetric segmentation of each TI, semiquantitative parameters and RF were extracted. All of the features were tested for significant differences between the two PET scanners. The performances of all of the features in predicting the nature of TIs were analyzed by testing three classes of final logistic regression predictive models, one for each tomograph and one with both scanners together. Some RF resulted significantly different between the two scanners. PET/CT semiquantitative parameters were not able to predict the final diagnosis of TIs while GLCM-related RF (in particular GLCM entropy_log2 e GLCM entropy_log10) together with some GLRLM-related and GLZLM-related features presented the best predictive performances. In particular, GLCM entropy_log2, GLCM entropy_log10, GLZLM SZHGE, GLRLM HGRE and GLRLM HGZE resulted the RF with best performances. Our study enabled the selection of some RF able to predict the final nature of TIs discovered at ¹⁸F-FDG PET/CT imaging. Classic semiquantitative and volumetric PET/CT parameters did not reveal these abilities. Furthermore, a good overlap in the extraction of RF between the two scanners was underlined.

Shared Decision Making for Radioiodine Therapy and the Actual Pattern of Care in Intermediate-Risk Differentiated Thyroid Carcinoma

Radioiodine therapy (RAI) is usually a standard procedure performed after thyroidectomy in differentiated thyroid cancer (DTC). While the indication for RAI in high-risk patients has been established in various national and international guidelines, there is an ongoing discussion with regard to intermediate-risk patients. In addition to the inconsistent definition of this risk category, the absence of large multinational prospective randomized controlled trials forms the basis of the debate. In this context, the actual pattern of care and national guidelines in the country where the patient is living plays an important role with respect to regional iodine supply and goiter prevalence, preoperative diagnostics (fine needle aspiration biopsy), and corresponding surgical strategies. Participatory decision-making between physician and informed patient, which is demanded in principle today anyway, is of particular importance in this situation. This article will discuss the approach of shared decision making for radioiodine therapy in intermediate-risk DTC.

Low-Iodine Diet of 4 Days Is Sufficient Preparation for 131I Therapy in Differentiated Thyroid Cancer Patients

CONTEXT

No consensus exists about the optimal duration of the low-iodine diet (LID) in the preparation of 131I therapy in differentiated thyroid cancer (DTC) patients.

OBJECTIVE

This work aimed to investigate if a LID of 4 days is enough to achieve adequate iodine depletion in preparation for 131I therapy. In addition, the nutritional status of the LID was evaluated.

METHODS

In this prospective study, 65 DTC patients treated at 2 university medical centers were included between 2018 and 2021. The patients collected 24-hour urine on days 4 and 7 of the LID and kept a food diary before and during the LID. The primary outcome was the difference between the 24-hour urinary iodine excretion (UIE) on both days.

RESULTS

The median 24-hour UIE on days 4 and 7 of the LID were not significantly different (36.1 mcg [interquartile range, 25.4-51.2 mcg] and 36.5 mcg [interquartile range, 23.9-47.7 mcg], respectively, P = .43). On day 4 of the LID, 72.1% of the DTC patients were adequately prepared (24-hour UIE < 50 mcg), and 82.0% of the DTC patients on day 7 (P = .18). Compared to the self-reported regular diet, DTC patients showed a significantly (P < .01) lower percentage of nutrient intake (calories, protein, calcium, iodine, and water) during the LID.

CONCLUSION

The 24-hour UIE on day 4 of the LID did not differ from day 7, and therefore shortening the LID from 7 to 4 days seems justified to prepare DTC patients for 131I therapy in areas with sufficient iodine intake and may be beneficial to maintain a sufficient nutritional intake during DTC treatment.

Dosing Therapeutic Radiopharmaceuticals in Obese Patients

The prevalence of obesity has increased dramatically in the Western population. Obesity is known to influence not only the proportion of adipose tissue but also physiological processes that could alter drug pharmacokinetics. Yet, there are no specific dosing recommendations for radiopharmaceuticals in this patient population. This could potentially lead to underdosing and thus suboptimal treatment in obese patients, while it could also lead to drug toxicity due to high levels of radioactivity. In this review, relevant literature is summarized on radiopharmaceutical dosing and pharmacokinetic properties, and we aimed to translate these data into practical guidelines for dosing of radiopharmaceuticals in obese patients. For radium-223, dosing in obese patients is well established. Furthermore, for samarium-153-ethylenediaminetetramethylene (EDTMP), dose-escalation studies show that the maximum tolerated dose will probably not be reached in obese patients when dosing on MBq/kg. On the other hand, there is insufficient evidence to support dose recommendations in obese patients for rhenium-168-hydroxyethylidene diphosphonate (HEDP), sodium iodide-131, iodide 131-metaiodobenzylguanidine (MIBG), lutetium-177-dotatate, and lutetium-177-prostate-specific membrane antigen (PSMA). From a pharmacokinetic perspective, fixed dosing may be appropriate for these drugs. More research into obese patient populations is needed, especially in the light of increasing prevalence of obesity worldwide.

Comparing High and Low-Dose Radio-Iodine Therapy in Thyroid Remnant Ablation Among Intermediate and Low-Risk Papillary Thyroid Carcinoma Patients-Single Centre Experience

The role of Iodine-131 therapy is well established as an adjuvant therapy and for thyroid remnant ablation in differentiated thyroid cancer (DTC); however controversy still exists regarding its appropriate dose. Purpose of this study was to compare the effectiveness of low-dose and high-dose Iodine-131 ablation therapies in low- and intermediate-risk PTC patients. Eighty-four patients were divided equally into Group I: Ablated with high dose of Iodine-131 and Group II: Ablated with low dose of Iodine-131. Iodine-131 WBS, serum TG levels and USG neck of all patients were performed at first presentation, 6 months, 1 year, and 2 years follow up. Results are as follows: Group I: 64%, 72%, and 76% intermediate-risk patients were disease free at the follow up intervals of 6 months, 1 year, and 2 years, respectively. Similarly 70%, 82%, and 82% low-risk patients were disease free at above mentioned intervals. Group II: 56%, 60%, and 64% were disease free among intermediate-risk patients while percentage of disease free low-risk patients was 70%, 76%, and 76% at follow up intervals. Low dose of radioactive Iodine-131 was found as effective as high dose in thyroid remnant ablation of PTC patients.

Alterations in Oral Microbiota of Differentiated Thyroid Carcinoma Patients With Xerostomia After Radioiodine Therapy

BACKGROUND AND AIMS

Oral xerostomia remains one of the most common complications of differentiated thyroid carcinoma patients (DTC) after radioiodine therapy (RAI). Environmental factors in the etiology of xerostomia are largely unknown. We aimed to characterize the oral microbiota signatures and related biological functions associated with xerostomia and identify environmental factors affecting them.

METHODS

Saliva was collected from 30 DTC patients with xerostomia (XAs), 32 patients without xerostomia (indicated as non-XAs) following RAI after total thyroidectomy, and 40 healthy people (HCs) for 16S rRNA sequencing analysis.

RESULTS

The oral microbiota of XAs and non-XAs exhibited significant differences in α and β diversities and bacterial taxa. The abundance of porphyromonas, fusobacterium, and treponema_2 were significantly higher in XAs, while the abundance of the streptococcus was lower in the microbiota of non-XAs. Fusobacterium, and porphyromonas were negatively correlated with unstimulated/stimulated whole salivary secretion (USW)/(SWS), while fusobacterium, porphyromonas, and treponema_2 genera levels were positively associated with cumulative radioiodine dose. PICRUSt2 and BugBase suggested a significant difference in the expression of potentially_pathogenic, anaerobic, gram_negative, the arachidonic acid metabolism, and lipopolysaccharide (LPS) biosynthesis between XAs and non-XAs, possibly interdependent on radioiodine-induced inflammation. NetShift analysis revealed that porphyromonas genus might play as a key driver during the process of xerostomia. Five genera effectively distinguished XAs from non-XAs (AUC = 0.87).

CONCLUSION

Our study suggests for the first time that DTC patients with xerostomia after RAI display microbiota profiles and associated functional changes that may promote a pro-inflammatory environment. Dysbiosis of the oral microbiota may contribute to exacerbating the severity of xerostomia. Our results provide a research direction of the interaction mechanism between oral microbiota alteration and the progress of xerostomia.

Radioactive Iodine for Papillary Thyroid Carcinoma

Radioactive iodine is given after total thyroidectomy for remnant ablation or treatment of residual/metastatic disease. The decision and dose of radioactive iodine should be in a personalized and patient-specific approach, taking account the clinical-pathological features, risk stratification, patient's preference, and facilities of the institutions. We review the principles and use of radioactive iodine in differentiated thyroid cancer.

Pregnancy Outcomes in Thyroid Cancer Survivors: A Propensity Score-Matched Cohort Study

BACKGROUND

Some female thyroid cancer survivors wish to become pregnant following their cancer treatment. Current studies have shown inconsistent results on pregnancy outcomes in these survivors; however, detailed information on the pathological type, treatment, and gestational thyroid function of these patients are not yet well documented, making the refined assessment of the influence of a history of thyroid cancer and related treatments on pregnancy outcomes challenging.

OBJECTIVE

To investigate the risk of adverse pregnancy outcomes in thyroid cancer survivors.

METHODS

This was a retrospective cohort study. We included all women aged between 19 and 45 years old who delivered between January 2019 and June 2020 in West China Second University Hospital of Sichuan University. Women with tumors other than thyroid cancer or other thyroid diseases were excluded. The included women were divided into survivors of thyroid cancer (survivors) and women without any history of thyroid disease (controls). Propensity score matching and logistic regression were used to control confounding variables.

RESULTS

All 18,332 women who met the inclusion criteria were included in the study (96 survivors of papillary thyroid cancer and 18,236 controls). After propensity score matching, 96 survivors and 192 controls were included. The survivors had higher levels of free thyroxine (15.47 [13.61-17.67] vs. 14.38 [13.20-15.81] pmol/mL; P<0.001) and higher levels of thyroid peroxidase antibodies (TPOAb) (43.55 [31.43-71.43] vs. 35.95 [28.00-48.03] U/mL; P=0.008) but similar levels of thyroid stimulating hormone (1.46 [0.56-3.15] vs. 1.36 [0.81-1.92] mIU/mL; P=0.142) than the controls. There were no significant differences in adverse pregnancy outcomes between survivors and controls. Fetal macrosomia was lower among survivors (OR: 0.077, 95% CI: 0.009-0.668. P=0.020) than controls. Additionally, survivors had reduced weight gain during pregnancy (13.0 [10.0-15.0] vs. 14.00 [11.00-16.00] kg, P=0.005) and reduced placental weight (563.0 [514.5-620.0] vs. 572.0 [520.0-650.0] g, P=0.019), albeit with small absolute differences. Thyroidectomy or radioiodine therapy did not adversely affect pregnancy outcomes.

CONCLUSION

A history of treated papillary thyroid cancer was not associated with adverse pregnancy outcomes.

A semiquantitative study of the optimal whole-body imaging time after 131I therapy for differentiated thyroid cancer

OBJECTIVE

We compared the efficacy of post-therapy whole-body scintigraphy (Tx-WBS) in terms of detecting lesions in patients with differentiated thyroid cancer (DTC) on days 3, 7, and 10 after ¹³¹I treatment, and we determined the optimal imaging time.

METHODS

Clinical data from 161 DTC patients treated with ¹³¹I were collected. All patients underwent day 3 imaging, but only 98 patients underwent day 3 and day 7 imaging, and 63 patients underwent day 3 and day 10 imaging at the same time. And the thyroid bed uptake was visually graded. The radioactivity ratios of the thyroid bed, neck lymph nodes, lungs, and liver (to the background) were calculated to allow a semiquantitative analysis.

RESULTS

Visual analysis showed that delayed imaging revealed more lymph node and lung radioactivity, early imaging showed more residual thyroid tissue, and significant differences in uptake were apparent at days 3, 7, and 10 (P < 0.001). Semiquantitative analysis revealed significant differences in the target-to-background ratios of the residual thyroid bed, lungs, and liver at days 3, 7, and 10. On these days, the imaging sensitivities in terms of detecting metastatic lymph nodes were 29.58%, 39.02%, and 19.35%, and the specificities were 75.56%, 75.86%, and 75% (P = 0.465, 0.154, and 0.763, respectively). In terms of lung metastasis detection, the sensitivities were 29.58%, 38.46%, and 13.33% respectively, and the specificities were 98.33%, 100%, and 95.83% (P < 0.001, < 0.001, and P=0.238).

CONCLUSION

More residual thyroid tissue can be detected by imaging on day 3; imaging on day 7 more effectively detects lung metastases than does imaging on day 3 or 10.

Prevention of salivary gland dysfunction in patients treated with radioiodine for differentiated thyroid cancer: A systematic review of randomized controlled trials

INTRODUCTION

Salivary gland dysfunction (e.g., sialadenitis and xerostomia) is the most common complication of radioactive iodine (RAI) therapy for differentiated thyroid cancer (DTC). Several methods have been used to reduce/prevent this adverse effect. We aimed to systematically review the effectiveness of non-pharmacological and pharmacological interventions in preventing RAI-induced salivary gland dysfunction in patients with DTC.

METHODS

A systematic review was conducted, according to PRISMA guidelines. The protocol was registered (PROSPERO: CRD42022295229). PubMed, Embase, Scopus, and the Cochrane Library electronic databases were searched from inception to November 2021. Inclusion criteria were randomized controlled trials of DTC patients who were older than 18 years and underwent RAI after thyroidectomy in which at least one studied group received an intervention to prevent salivary gland dysfunction.

RESULTS

Twelve studies (a total of 667 participants) were included. Among DTC patients who were treated with RAI, nonpharmacological treatment such as parotid gland massage and aromatherapy ameliorated salivary gland dysfunction. Antioxidants such as vitamin E and selenium demonstrated radioprotective effects on the salivary gland, while other antioxidants did not show radioprotective benefits. Vitamin C showed no significant effects on preventing salivary gland dysfunction. Amifostine had inconsistent outcomes among studies. Among cholinergic agonists, pilocarpine did not demonstrate the radioprotective effect on parotid glands, while bethanechol lowered salivary gland dysfunction. However, the negative results from pilocarpine may be explained by the strong sialorrheic effect of the Cincinnati regimen in both study arms.

CONCLUSION

Among non-pharmacological and pharmacological methods, parotid gland massage, aromatherapy, vitamin E, selenium, amifostine, and bethanechol may have benefits in minimizing RAI-induced salivary gland dysfunction in patients with DTC. The results are limited by a small number of patients and should be confirmed in future larger randomized controlled trials.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=295229, PROSPERO, identifier CRD42022295229.

Global Hotspots and Prospects of I-131 Therapy in Thyroid Carcinoma via Bibliometric Analysis

Background

Hundreds of studies have reported the application of iodine-131 (I-131) in thyroid carcinoma (THCA) in past years. However, the status of research in the field and other related topics have not been investigated. This study aimed to identify the cooperation of authors, countries, and institutions, as well as explore the hot topics and prospects regarding I-131 therapy in THCA based on previous studies.

Methods

Publications from 2010 to 2020 were retrieved from Web of Science Core Collection according to research strategy. Bibliometric analyses were performed using VOSviewer 1.6.15 and CiteSpace 5.7.3 to evaluate and visualize the cooperation network, hot topic, and research frontier.

Results

The number of publications showed a trend of fluctuation between 2010 and 2020. We identified 1387 publications related to I-131 therapy in THCA, which were published by 1628 institutions from 82 countries. The largest proportion of publications were emanated from the USA, and the majority of papers were published by Thyroid. Shanghai Jiao Tong University of China contributed the most papers. Although many authors participated in the research of this field, high-yield authors were few. Co-occurrence analysis classified keywords into five clusters, including assessment, efficacy measurement, monitoring, hormone regulation, and guidelines of I-131 therapy. The terms “bone marrow dosimetry and time” were among the latest hotspots. The research frontier topic in I-131 therapy focused on the “P53 and anti-Müllerian hormone”.

Conclusion

The attention to I-131 therapy in THCA should be increased considerably. It was necessary to construct active co-operations between authors, countries, and institutions to promote the development of this field. Recent researches referred to the timing and dose assessment of I-131 therapy in THCA. Future studies likely focused on targeted therapy and adverse effects evaluation were worthy of research as well.

Expanding Theranostic Radiopharmaceuticals for Tumor Diagnosis and Therapy

Radioligand theranostics (RT) in oncology use cancer-type specific biomarkers and molecular imaging (MI), including positron emission tomography (PET), single-photon emission computed tomography (SPECT) and planar scintigraphy, for patient diagnosis, therapy, and personalized management. While the definition of theranostics was initially restricted to a single compound allowing visualization and therapy simultaneously, the concept has been widened with the development of theranostic pairs and the combination of nuclear medicine with different types of cancer therapies. Here, we review the clinical applications of different theranostic radiopharmaceuticals in managing different tumor types (differentiated thyroid, neuroendocrine prostate, and breast cancer) that support the combination of innovative oncological therapies such as gene and cell-based therapies with RT.

Radiation Safety and Accidental Radiation Exposures in Nuclear Medicine

Medical radiation accidents and unintended events may lead to accidental or unintended medical exposure of patients and exposure of staff or the public. Most unintended exposures in nuclear medicine will lead to a small increase in risk; nevertheless, these require investigation and a clinical and dosimetric assessment. Nuclear medicine staff are exposed to radiation emitted directly by radiopharmaceuticals and by patients after administration of radiopharmaceuticals. This is particularly relevant in PET, due to the penetrating 511 keV γ-rays. Dose constraints should be set for planning the exposure of individuals. Staff body doses of 1-25 µSv/GBq are reported for PET imaging, the largest component being from the injection. The preparation and administration of radiopharmaceuticals can lead to high doses to the hands, challenging dose limits for radionuclides such as ⁹⁰Y and even ¹⁸F. The risks of contamination can be minimized by basic precautions, such as carrying out manipulations in purpose-built facilities, wearing protective clothing, especially gloves, and removing contaminated gloves or any skin contamination as quickly as possible. Airborne contamination is a potential problem when handling radioisotopes of iodine or administering radioaerosols. Manipulating radiopharmaceuticals in laminar air flow cabinets, and appropriate premises ventilation are necessary to improve safety levels. Ensuring patient safety and minimizing the risk of incidents require efficient overall quality management. Critical aspects include: the booking process, particularly if qualified medical supervision is not present; administration of radiopharmaceuticals to patients, with the risk of misadministration or extravasation; management of patients' data and images by information technology systems, considering the possibility of misalignment between patient personal data and clinical information. Prevention of possible mistakes in patient identification or in the management of patients with similar names requires particular attention. Appropriate management of pregnant or breast-feeding patients is another important aspect of radiation safety. In radiopharmacy activities, strict quality assurance should be implemented at all operational levels, in addition to adherence to national and international regulations and guidelines. This includes not only administrative aspects, like checking the request/prescription, patient's data and the details of the requested procedure, but also quantitative tests according to national/international pharmacopoeias, and measuring the dispensed activity with a calibrated activity meter prior to administration. In therapy with radionuclides, skin tissue reactions can occur following extravasation, which can result in localized doses of tens of Grays. Other relevant incidents include confusion of products for patients administered at the same time or malfunction of administration devices. Furthermore, errors in internal radiation dosimetry calculations for treatment planning may lead to under or over-treatment. According to literature, proper instructions are fundamental to keep effective dose to caregivers and family members after patient discharge below the Dose constraints. The IAEA Basic Safety Standards require measures to minimize the likelihood of any unintended or accidental medical exposures and reporting any radiation incident. The relative complexity of nuclear medicine practice presents many possibilities for errors. It is therefore important that all activities are performed according to well established procedures, and that all actions are supported by regular quality assurance/QC procedures.

Dosimetry of nuclear medicine therapies: current controversies and impact on treatment optimization

Nuclear medicine therapeutic procedures have considerably expanded over the last few years, and their number is expected to grow exponentially in the future. Internal dosimetry has significantly developed as well, but has not yet been uniformly accepted as a valuable tool for prediction of therapeutic efficacy and toxicity. In this paper, we briefly summarize some of the arguments about the implementation of internal dosimetry in clinical practice. In addition, we provide a few examples of radionuclide anticancer therapies for which internal dosimetry demonstrated a significant impact on treatment optimization and patient outcome.

Myeloid Toxicity of Radionuclide Cancer Therapy

Emergent genomic analytic techniques in patients with cancer offer the potential to define the risk of myelo dysplastic syndrome (MDS) and acute leukemia (AL) manifesting following targeted radionuclide therapy of metastatic lymphoma, neuroendocrine tumors (NETs), and prostate cancer. Characterization of the genetic profile will allow risk stratification of patients before theranostic radionuclide management of advanced cancers and offers the opportunity to minimize toxicity while preserving optimal individualized efficacy in the practice of personalized precision nuclear oncology. Our review of a single-center experience of prospective radionuclide theranostic management of metastatic non-Hodgkin lymphoma (NHL), NETs, and castration-resistant prostate cancer (metastatic castrate-resistant prostate cancer [mCRPC]) over the past decade, and comparison with published studies, shows that while the risk of significant myelotoxicity is generally low, at <3%, the consequences in the small minority of patients who develop MDS or AL are substantial, and survival is poor. Timely identification of patients at heightened risk of hematologic toxic complication, using novel genomic technology before institution of radionuclide therapy, will facilitate amelioration of myelotoxicity. In current clinical practice, the minimal hematological toxicity of chemo-free theranostic management of advanced cancer is significantly less compared with newly adopted chemotherapy -immunotherapy regimens, and the financial toxicity associated with these novel agents is avoided.

Radioiodine therapy in patient of differentiated thyroid cancer with end-stage renal disease on maintenance hemodialysis: case report with review of literature

Surgical resection followed by radioactive-iodine (¹³¹I) therapy constitutes a standard treatment for differentiated thyroid cancer (DTC). ¹³¹I is normally excreted through kidneys and treatment of patients with end stage renal disease (ESRD) on hemodialysis requires special attention for dosage of ¹³¹I, timing of dialysis and radiation safety. We present a case of a post-thyroidectomy patient with ESRD on haemodialysis who required radioactive iodine ablation with review of literature.

Review of extremity dosimetry in nuclear medicine

The exposure of the fingers is one of the major radiation protection concerns in nuclear medicine (NM). The purpose of this paper is to provide an overview of the exposure, dosimetry and protection of the extremities in NM. A wide range of reported finger doses were found in the literature. Historically, the highest finger doses are found at the fingertip in the preparation and dispensing of¹⁸F for diagnostic procedures and⁹⁰Y for therapeutic procedures. Doses can be significantly reduced by following recommendations on source shielding, increasing distance and training. Additionally, important trends contributing to a lower dose to the fingers are the use of automated procedures (especially for positron emission tomography (PET)) and the use of prefilled syringes. On the other hand, the workload of PET procedures has substantially increased during the last ten years. In many cases, the accuracy of dose assessment is limited by the location of the dosimeter at the base of the finger and the maximum dose at the fingertip is underestimated (typical dose ratios between 1.4 and 7). It should also be noted that not all dosimeters are sensitive to low-energy beta particles and there is a risk for underestimation of the finger dose when the detector or its filter is too thick. While substantial information has been published on the most common procedures (using^99mTc,¹⁸F and⁹⁰Y), less information is available for more recent applications, such as the use of⁶⁸Ga for PET imaging. Also, there is a need for continuous awareness with respect to contamination of the fingers, as this factor can contribute substantially to the finger dose.

Use of Salivary Iodine Concentrations to Estimate the Iodine Status of Adults in Clinical Practice

BACKGROUND

Measurement of the 24-h urinary iodine concentration or urinary iodine excretion (UIE) is the gold standard to determine iodine status; however, this method is inconvenient. The use of salivary iodine could be a possible alternative since salivary glands express the sodium-iodine symporter.

OBJECTIVES

We aimed to establish the correlation between the salivary iodine secretion and UIE, to evaluate the clinical applicability of the iodine saliva measurement.

METHODS

We collected 24-h urine and saliva samples from 40 participants ≥18 y: 20 healthy volunteers with no specific diet (group 1), 10 patients with differentiated thyroid cancer with a low dietary intake (<50 μg/d, group 2), and 10 patients with a high iodine status as the result of the use of amiodarone (group 3). Urinary and salivary iodine were measured using a validated inductively coupled plasma MS method. To correct for differences in water content, the salivary iodine concentration (SIC) was corrected for salivary protein and urea concentrations (SI/SP and SI/SU, respectively). The intra- and inter-individual CVs were calculated, and the Kruskal-Wallis test and Spearman's correlation were used.

RESULTS

The intra-individual CVs for SIC, SI/SP, and SI/SU were 63.8%, 37.7%, and 26.9%, respectively. The inter-individual CVs for SIC, SI/SP, and SI/SU were 77.5%, 41.6% and 47.0%, respectively. We found significant differences (P < 0.01) in urinary and salivary iodine concentrations between all groups [the 24-h UIE values were 176 μg/d (IQR, 96.1-213 μg/d), 26.0 μg/d (IQR, 22.0-37.0 μg/d), and 10.0*103 μg/d (IQR, 7.57*103-11.4*103 μg/d) in groups 1-3, respectively; the SIC values were 136 μg/L (IQR, 86.3-308 μg/L), 71.5 μg/L (IQR, 29.5-94.5 μg/L), and 14.3*103 μg/L (IQR, 10.6*103-25.6*103 μg/L) in groups 1-3, respectively]. Correlations between the 24-h UIE and SIC, SI/SP, and SI/SU values were strong (ρ = 0.80, ρ = 0.90, and ρ = 0.86, respectively; P < 0.01).

CONCLUSIONS

Strong correlations were found between salivary and urinary iodine in adults with different daily iodine intakes. A salivary iodine measurement can be performed to assess the total iodine body pool, with the recommendation to correct for salivary protein or urea.

Sialadenitis as a complication of radioiodine therapy in patients with thyroid cancer: where do we stand?

PURPOSE

This study aims to elaborate on the current knowledge concerning the mechanism, frequency, clinical manifestations, diagnostic procedures, prevention, and management of radioactive iodine (RAI)-induced sialadenitis in patients receiving treatment for differentiated thyroid cancer (DTC).

METHODS

A review of the literature was carried out through the " www.ncbi.nlm.nih.gov/pubmed " database focusing on the results of the past decade.

RESULTS

The high concentration of RAI in the salivary glands results in high beta radiation exposure of the striated duct cells and stem cells. This exposure leads to acute and/or chronic sialadenitis with obstructive symptoms and progressive loss of salivary gland function and xerostomia, with severe impact on patients' quality of life. No standard diagnostic method has been established. As far as prevention is concerned, many approaches have been proposed, such as sialogogues, local massage, vitamin E, and amifostine administration. Although there is no unanimity as to their effectiveness, the use of sialogogues is recommended. Treatment includes conservative drug therapy and sialendoscopy when necessary.

CONCLUSION

RAI-induced sialadenitis has a major impact on patients' quality of life. Due to the good prognosis of DTC, the reduction of sialadenitis and its prognosis, prevention, and treatment constitute a priority for the overall treatment of these patients. Further studies that will establish a coherent treatment protocol for this condition are necessary.

Clinical Management of End-Stage Renal Disease Patients on Dialysis Receiving Radioactive Iodine Treatment

PURPOSE

Radioactive iodine (RAI) is used to treat thyroid cancer patients with a clear paradigm for most patients. End-stage renal disease (ESRD) patients pose several challenges when undergoing RAI treatment, primarily due to the lack of renal clearance. We retrospectively report our experience with RAI treatment in a cohort of patients with ESRD and provide a set of recommendations on aspects such as the need for adjusted dose activity, balancing scheduling between RAI therapy and dialysis, and radiation safety precautions.

PATIENTS AND METHODS

In this study, we report on 5 patients (6 cases), with ESRD on dialysis, treated with RAI for thyroid cancer. Retention measurements to determine individual biological clearance of RAI from the patient's body before and after dialysis sessions were assessed using external exposure dose rates measured at 1 m.

RESULTS

Delayed biological clearance of RAI, after the first hemodialysis session, resulted in a longer RAI effective half-life as a consequence of longer retention periods, consistent with observations reported in scientific literature. To achieve a much closer radiation exposure compared with a nondialysis patient, one would recommend administering ~20%-30% of the dose activity normally administered to a thyroid cancer patient based on their medical history, histopathology, and uptake with the appropriate dialysis schedule.

CONCLUSIONS

Special precautions should be taken with the administration of RAI in ESRD patients by adjusting the prescribed dose activity, dialysis sessions, and paying special attention to wastes. Pooling data from multiple centers may be useful to build a consensus and substantiated recommendations.

Prognostic Role of 2-[18F]FDG PET/CT Metabolic Volume Parameters in Patients Affected by Differentiated Thyroid Carcinoma with High Thyroglobulin Level, Negative 131I WBS and Positive 2-[18F]-FDG PET/CT

The clinical and prognostic role of 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (2-[¹⁸F]FDG PET/CT) in the study of patients affected by differentiated thyroid carcinoma (DTC) with positive serum thyroglobulin (Tg) level and negative [¹³¹I] whole-body scan ([¹³¹I]WBS) has already been demonstrated. However, the potential prognostic role of semi-quantitative PET metabolic volume features, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), has not yet been clearly investigated. The aim of this retrospective study was to investigate whether the main metabolic PET/CT parameters may predict the prognosis. We retrospectively included 122 patients with a positive 2-[¹⁸F]FDG PET/CT for DTC disease after a negative [¹³¹I]WBS with Tg > 10 ng/mL. The maximum and mean standardized uptake value (SUVmax and SUVmean), MTV and TLG of the hypermetabolic lesion, total MTV (tMTV) and total TLG (tTLG) were measured for each scan. Progression-free survival (PFS) and overall survival (OS) curves were plotted according to the Kaplan-Meier analysis. After a median follow up of 53 months, relapse/progression of disease occurred in 87 patients and death in 42. The median PFS and OS were 19 months (range 1-132 months) and 46 months (range 1-145 months). tMTV and tTLG were the only independent prognostic factors for OS. No variables were significantly correlated with PFS. The best thresholds derived in our sample were 6.6 cm³ for MTV and 119.4 for TLG. In patients with negative WBS and Tg > 10 ng/mL, 2-[¹⁸F]FDG PET/CT metabolic volume parameters (tMTV and tTLG) may help to predict OS.

Radiation exposure to allied health personnel handling blood specimens from patients receiving radioactive iodine-131 and recombinant human TSH (thyrogen®) stimulation

With increasing use of recombinant human TSH (rhTSH) stimulation protocol in radioactive iodine-131 treatment of thyroidectomised differentiated thyroid carcinoma (DTC), there is increasing concern regarding radiation safety during collection and processing of radioactive blood samples. Our study aims to quantify this radiation exposure in the context of current radiation guidelines to provide a practical safety framework. We analysed 45 patients prospectively referred to a tertiary centre in Singapore, who had histologically proven DTC, and who were thyroidectomised and planned for I-131 with rhTSH stimulation. Each patient received rhTSH for two consecutive days, with I-131 administered 24 h after, and a stimulated Thyroglobulin blood sample collected and processed 72 h after the last rhTSH dose. We measured radiation exposures with dosimeters. Based on the average and maximum exposure rates calculated, we extrapolated and derived the number of radioactive blood samples that could be safely collected and processed. Mean hand and body radiation exposures during venepuncture and blood processing were generally significantly higher than background radiation. Based on average exposure rates, the permissible number of blood samples that can be collected and processed is 9.09 × 10³per year (24 per day) and 8.70 × 10⁴per year (238 per day), respectively. This is the first study to date to extrapolate permissible thresholds that can serve as a practical guideline to the number of radioactive blood samples which can be safely collected and processed, following radioactive iodine therapy, within the limits of current radiation guidelines. Once validated, generalisations to other radioactive therapies may be considered.

The role of Tg kinetics in predicting 2-[18F]-FDG PET/CT results and overall survival in patients affected by differentiated thyroid carcinoma with detectable Tg and negative 131I-scan

PURPOSE

The aim of this study was to assess the potential role of thyroglobulin (Tg) kinetics in predicting 2-[¹⁸F]-FDG-PET/CT results and overall survival (OS) in patients affected by differentiated thyroid carcinoma (DTC) and suspected recurrence.

METHODS

On hundred and thirty-nine patients were retrospectively included. All patients underwent 2-[¹⁸F]-FDG-PET/CT due to detectable Tg levels and negative [¹³¹I] whole-body scan. The last two consecutive serum Tg measurements before PET/CT were used for Tg-doubling time (TgDT) and Tg-velocity (Tg-vel) calculation. Receiver operating characteristic (ROC) curves were used to determine the optimal cutoff points for Tg, TgDT and Tg-vel for predicting PET/CT results.

RESULTS

One hundred and fifteen (83%) patients had positive PET/CT for DTC recurrence, while the remaining 24 (17%) negative. Stimulated Tg before PET and Tg-vel were significantly higher in patients with a positive PET/CT scan than negative scan (average Tg 190 vs 14 ng/mL, p = 0.006; average Tg-vel 4.2 vs 1.7 ng/mL/y, p < 0.001). Instead, TgDT was significantly shorter in positive scan (average TgDT 1.4 vs 4.4 years, p < 0.001). ROC curve analysis revealed the best Tg, TgDT and Tg-vel cutoff of 18 ng/mL,1.36 years and 1.95 ng/mL/y. In patients with Tg<18 ng/mL, the PET/CT detection rate was significantly lower in patients with low Tg-vel (p = 0.018) and with long TgDT (p = 0.001). ATA class risk, PET/CT results and Tg before PET were confirmed to be independent prognostic variables for OS.

CONCLUSIONS

Tg kinetics may help to predict 2-[¹⁸F]-FDG-PET/CT results in DTC patients with negative [¹³¹I]WBS and detectable Tg, especially in case of low-moderate Tg.

Ferroptosis-related gene model to predict overall survival of papillary thyroid carcinoma

BACKGROUND

Ferroptosis is a form of programmed cell death that is closely associated with the development of various tumors. However, the correlation between ferroptosis and papillary thyroid carcinoma (PTC) is unclear. This study was performed to investigate the expression and prognostic value of ferroptosis-related genes (FRG) in PTC.

METHODS

mRNA expression profiles and corresponding clinical data of patients with PTC were analyzed to identify factors affecting prognosis. Independent risk factors were used to establish a predictive receiver operating characteristic model. Single-sample gene set enrichment analysis (ssGSEA) was used to evaluate the correlation between ferroptosis and immune cells.

RESULTS

Most genes related to FRG (78.8%) were differentially expressed between the tumor and adjacent normal tissues. In univariate Cox regression analysis, 12 differentially expressed genes were associated with prognostic survival. We constructed a prognostic model of eight FRG, including DPP4, GPX4, GSS, ISCU, MIOX, PGD, TF, and TFRC, and divided patients into two groups: high and low risk. The high-risk group exhibited a significantly reduced overall survival rate. In multivariate Cox regression analysis, the risk score was used as an independent prognostic factor. ssGSEA showed that immune cell types and their expression in the high- and low-risk groups were significant.

CONCLUSION

This study constructed a prognostic model of ferroptosis-related genes and determined its usefulness as an independent prognostic factor, providing a reference for the treatment and prognosis of patients with PTC.

Development and validation of a three-immune-related gene signature prognostic risk model in papillary thyroid carcinoma

PURPOSE

Increasing evidence indicates that there is a correlation between papillary thyroid carcinoma (PTC) prognosis and the immune signature. Our goal was to construct a new prognostic tool based on immune genes to achieve more accurate prognosis predictions and earlier diagnoses of PTC.

METHODS

The 493 PTCs samples and 58 tumor-adjacent normal tissues were obtained from The Cancer Genome Atlas database (TCGA). Immune genes were obtained from the ImmPort database. First, this cohort was randomly divided into training cohort and testing cohort. Second, the differentially expressed (DE) immune genes from the training set were used to construct the prognostic model. Then, the testing and entire data cohorts were used to validate the model, and the data were analyzed to determine the correlation of the clinical prognostic model with immune cell infiltration and expression profiles of human leukocyte antigen (HLA) genes. Finally, an analysis of the gene ontology (GO) annotation was performed.

RESULTS

A total of 189 upregulated and 128 downregulated DE immune genes were identified. We developed and validated a three-immune gene model for PTC that includes Hsp70, NOX5, and FGF23. This model was demonstrated to be an independent prognostic variable. In addition, the overall immune activity of the high-risk group was higher than that of the low-risk group.

CONCLUSIONS

We developed and validated a three-immune gene model for PTC that includes HSPA1A, NOX5, and FGF23. This model can be used as a validated tool to predict outcomes in PTC.

Post-Surgical Ablative or Adjuvant Radioiodine Therapy Has No Impact on Outcome in 1-4 cm Differentiated Thyroid Cancers without Extrathyroidal Extension

Whether to conduct remnant ablation or adjuvant radioactive iodine (RAI) therapy in patients with intrathyroidal differentiated thyroid carcinoma (DTC), sized 1.1-4 cm, is debated. We evaluated the impact of RAI on outcome in this category of DTCs. We retrospectively enrolled 308 patients submitted to total thyroidectomy: 198 had tumors sized 1.1-2 cm (Group 1) and 110 of 2.1-4 cm (Group 2). Both groups were divided into patients receiving and not receiving RAI after surgery. RAI+ and RAI- patients did not significantly differ, regarding several clinical and pathological features. Final outcome was defined according to dynamic risk stratification. Remission was observed in the majority of Group 1 and Group 2 patients and outcome did not significantly differ between RAI+ and RAI- patients: respectively, 95.8% vs. 93.7% in Group 1, and 87.7% vs. 86.5% in Group 2. The majority of persistent cases, either RAI+ or RAI-, received therapeutic RAI administration, and about 50% of RAI- cases had an excellent response at final follow up, whereas no RAI+ persistent patients had a beneficial effect. Our findings demonstrate that patients with an intrathyroidal DTC sized 1.1-4 cm do not benefit from RAI. The outcome of these patients remains favorable, and the few patients with persistent diseases can be treated with RAI during follow up.

The effect of eating on the uptake of PSMA ligands in the salivary glands

Rationale

PSMA-directed therapy for metastatic prostate cancer is gaining adoption as a treatment option. However, accumulation of ¹⁷⁷Lu/²²⁵Ac-PSMA in the salivary glands remains a problem, with risk of dose-limiting xerostomia and potentially severe effect on the quality of life. Gustatory stimulation is an approach that has commonly been used in radioactive iodine therapy to reduce accumulation in the salivary glands. However, based on theoretical differences in biodistribution, it was hypothesized that this could potentially lead to adverse increased toxicity for PSMA-ligand therapy. The primary objective of this work was to determine if gustatory stimulation by eating an assortment of sweet/fatty/acidic foods during the biodistribution phase of [¹⁸F]DCFPyl could result in a clinically relevant (> 30%) change in the uptake of the tracer in the salivary glands.

Methods

10 patients who already received a whole-body [¹⁸F]DCFPyl PET/CT scan for evaluation of prostate cancer, underwent a repeat (intervention) PET/CT scan within a month of the first (control) scan. During the intervention scan, patients chose from an assortment of sweet/fatty/acidic foods, which they then chewed and swallowed for a period of time starting 1 min before tracer administration to 10 min thereafter. Data from both scans were analyzed by placing VOIs on the major salivary glands and segmenting them using relative thresholds.

Results

A slight increase in PSMA uptake in the parotid glands was observed on the intervention scan when compared to the baseline scan (+ 7.1% SUL_mean and + 9.2% SUL_max, p < 0.05). No significant difference in PSMA uptake in the submandibular glands was seen.

Conclusions

Eating only slightly increases uptake of [¹⁸F]DCFPyl in the parotid glands. We nonetheless recommend refraining from gustatory stimulation during the administration and early biodistribution phase of radionuclide therapy with PSMA-ligands to reduce the risk of avoidable additional toxicity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00838-y.

Advances in Functional Imaging of Differentiated Thyroid Cancer

Simple Summary

Since the 1940s, radioactive iodine has been used for functional imaging and for treating patients with differentiated thyroid cancer (DTC). During this long-lasting experience, the use of iodine isotopes evolved, especially during the last years due to improved knowledge of thyroid cancer biology and improved performances of imaging tools. The present review summarizes recent advances in the field of functional imaging and theragnostic approach of DTC.

Abstract

The present review provides a description of recent advances in the field of functional imaging that takes advantage of the functional characteristics of thyroid neoplastic cells (such as radioiodine uptake and FDG uptake) and theragnostic approach of differentiated thyroid cancer (DTC). Physical and biological characteristics of available radiopharmaceuticals and their use with state-of-the-art technologies for diagnosis, treatment, and follow-up of DTC patients are depicted. Radioactive iodine is used mostly with a therapeutic intent, while PET/CT with ¹⁸F-FDG emerges as a useful tool in the diagnostic management and complements the use of radioactive iodine. Beyond ¹⁸F-FDG PET/CT, other tracers including ¹²⁴I, ¹⁸F-TFB and ⁶⁸Ga-PSMA, and new methods such as PET/MR, might offer new opportunities in selecting patients with DTC for specific imaging modalities or treatments.

Effect of TSH stimulation protocols on adequacy of low-iodine diet for radioiodine administration

Low-iodine diet (LID) is a crucial preparation for radioactive iodine (RAI) treatment or scan in thyroid cancer. The aim of this study is to analyze the influence of thyroid stimulating hormone (TSH) stimulation protocols and other clinical factors on LID adequacy. Thyroid cancer patients who underwent LID for RAI scan or treatment were retrospectively analyzed. Patients were guided to have LID for 2 weeks before RAI administration and urine iodine/creatinine ratio (UICR, μg/g Cr) was measured. TSH stimulation was conducted using either thyroid hormone withdrawal (THW) or recombinant human TSH (rhTSH) injection. Adequacy of LID was classified by UICR as ‘excellent (< 50)’, ‘adequate (50–100)’, ‘inadequate (101–250)’ and ‘poor (> 250)’. A total of 1715 UICR measurements from 1054 patients were analyzed. UICR was significantly higher in case of rhTSH use than THW (72.4 ± 48.1 vs. 29.9 ± 45.8 μg/g Cr, P < 0.001). In patients who underwent LID twice using both TSH stimulation protocols alternately, UICR was higher in case of rhTSH than THW regardless of the order of method. Among clinical factors, female, old-age, and the first LID were significant factors to show higher UICR. Although the adequacy of LID was ‘adequate’ or ‘excellent’ in most patients, multivariate analysis demonstrated that THW method, male, young age, and prior LID-experience were significant determinants for achieving ‘excellent’ adequacy of LID. In conclusion, UICR was higher and the proportion of ‘excellent’ LID adequacy was lower with rhTSH than with THW. UICR was higher also in women, old-age, and LID-naïve patients. Further researches are required to suggest effective methods to reduce body iodine pool in case of rhTSH use and to validate the efficacy of such methods on outcomes of RAI treatment.

Silicon-photomultiplier-based PET/CT reduces the minimum detectable activity of iodine-124

The radioiodine isotope pair 124I/131I is used in a theranostic approach for patient-specific treatment of differentiated thyroid cancer. Lesion detectability is notably higher for 124I PET (positron emission tomography) than for 131I gamma camera imaging but can be limited for small and low uptake lesions. The recently introduced silicon-photomultiplier-based (SiPM-based) PET/CT (computed tomography) systems outperform previous-generation systems in detector sensitivity, coincidence time resolution, and spatial resolution. Hence, SiPM-based PET/CT shows an improved detectability, particularly for small lesions. In this study, we compare the size-dependant minimum detectable 124I activity (MDA) between the SiPM-based Biograph Vision and the previous-generation Biograph mCT PET/CT systems and we attempt to predict the response to 131I radioiodine therapy of lesions additionally identified on the SiPM-based system. A tumour phantom mimicking challenging conditions (derived from published patient data) was used; i.e., 6 small spheres (diameter of 3.7-9.7 mm), 9 low activity concentrations (0.25-25 kBq/mL), and a very low signal-to-background ratio (20:1). List-mode emission data (single-bed position) were divided into frames of 4, 8, 16, and 30 min. Images were reconstructed with ordinary Poisson ordered-subsets expectation maximization (OSEM), additional time-of-flight (OSEM-TOF) or TOF and point spread function modelling (OSEM-TOF+PSF). The signal-to-noise ratio and the MDA were determined. Absorbed dose estimations were performed to assess possible treatment response to high-activity 131I radioiodine therapy. The signal-to-noise ratio and the MDA were improved from the mCT to the Vision, from OSEM to OSEM-TOF and from OSEM-TOF to OSEM-TOF+PSF reconstructed images, and from shorter to longer emission times. The overall mean MDA ratio of the Vision to the mCT was 0.52 ± 0.18. The absorbed dose estimations indicate that lesions ≥ 6.5 mm with expected response to radioiodine therapy would be detectable on both systems at 4-min emission time. Additional smaller lesions of therapeutic relevance could be detected when using a SiPM-based PET system at clinically reasonable emission times. This study demonstrates that additional lesions with predicted response to 131I radioiodine therapy can be detected. Further clinical evaluation is warranted to evaluate if negative 124I PET scans on a SiPM-based system can be sufficient to preclude patients from blind radioiodine therapy.

Safe use of radiopharmaceuticals in patients with chronic kidney disease: a systematic review

BACKGROUND

Patients with chronic kidney disease (CKD) may need to have their radiopharmaceutical dosage adjusted to prevent adverse effects and poor outcomes, but there are few recommendations on radiopharmaceutical dosing for this group of patients. The aim of this study is to provide an overview of the available information on radiopharmaceutical dose recommendations for patients with CKD.

METHODS

We performed a systematic literature review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We conducted a literature search in the MEDLINE (PubMed) and Embase databases and screened potentially relevant studies using inclusion and exclusion criteria. We independently assessed the included observational studies' methodologies and extracted relevant data.

RESULTS

Of the 5795 studies first identified, 34 were included in this systematic review. These studies described three radiopharmaceuticals: [131I]sodium iodine, [18F]fludeoxyglucose, and [131I]iobenguane. Twenty-nine studies (85.3%) reported data on patients with CKD stage 5, while only three studies mentioned CKD patients in other stages (8.8%).

CONCLUSION

We found no consistent recommendations for radiopharmaceutical dosing in patients with CKD. Although some studies do mention dosing difficulties in patients with CKD, information is available for only a few radiopharmaceuticals, and recommendations are sometimes contradictory. Further research on radiopharmaceutical dosing in patients with CKD is needed to determine whether these patients require specific dosing, especially for therapeutic radiopharmaceuticals where a non-optimised dose may lead to an increased risk of toxicity for non-targeted organs. Including patients with CKD in studies and providing specific information about dosing in these patients should be a priority for the radiopharmaceutical community.

MANAGEMENT OF DIFFERENTIATED THYROID CANCER: THE STANDARD OF CARE

In the past decade the management of differentiated thyroid cancer (DTC) underwent a paradigm shift towards the use of risk-stratification with the goal of maximizing benefit and minimizing morbidity of radioiodine (¹³¹I) therapy. ¹³¹I therapy is guided by information derived from surgical histopathology, molecular markers, postoperative diagnostic radioiodine scintigraphy and thyroglobulin (Tg) levels. ¹³¹I is used for diagnostic imaging and therapy of DTC based on physiologic sodium-iodine symporter expression in normal and neoplastic thyroid tissue. We summarize the essential information at the core of multidisciplinary DTC management, which emphasizes individualization of ¹³¹I therapy according to the patient's risk for tumor recurrence.

Urinary iodine concentration and radioactive iodine therapeutic response in patients with differentiated thyroid cancer

Aim: Urinary iodine concentration (UIC) may assess radioactive iodine ablation. Materials & methods: According the 2015 American Thyroid Association guidelines, patients were categorized into low- to intermediate-risk or high-risk groups. The iodine concentration in the morning urine specimens was measured by the ceric ion-arsenious acid method. Results: In the low- to intermediate-risk group (113 cases), nonexcellent response (non-ER) was associated with higher UIC, higher UIC subgroups (p < 0.05), higher pre-ablative stimulated thyroglobulin levels (p < 0.01). In the high-risk group (68 cases), the non-ER rate was higher in the higher pre-ablative stimulated thyroglobulin group (p < 0.01), but not significantly different between the UIC and UIC subgroups (p > 0.05). Conclusion: The non-ER rate was related to UIC in the low- to intermediate-risk group; however, UIC did not affect the non-ER rate in the high-risk group.

Dosimetry during adjuvant 131I therapy in patients with differentiated thyroid cancer-clinical implications

The activity of radioiodine (¹³¹I) used in adjuvant therapy for thyroid cancer ranges between 30 mCi (1.1 GBq) and 150 mCi (5.5 GBq). Dosimetry based on Marinelli's formula, taking into consideration the absorbed dose in the postoperative tumour bed (D) should systematise the determination of ¹³¹I activity. Retrospective analysis of 57 patients with differentiated thyroid cancer (DTC) after thyreidectomy and adjuvant ¹³¹I therapy with the fixed activity of 3.7 GBq. In order to calculate D from Marinelli's formula, the authors took into account, among other things, repeated dosimetry measurements (after 6, 24, and 72 h) made during scintigraphy and after administration of the therapeutic activity or radioiodine. In 75% of the patients, the values of D were > 300 Gy (i.e. above the value recommended by current guidelines). In just 16% of the patients, the obtained values fell between 250 and 300 Gy, whereas in 9% of the patients, the value of D was < 250 Gy. The therapy was successful for all the patients (stimulated Tg < 1 ng/ml and ¹³¹I uptake < 0.1% in the thyroid bed in follow-up examination). Dosimetry during adjuvant ¹³¹I therapy makes it possible to diversify the therapeutic activities of ¹³¹I in order to obtain a uniform value of D.