Prognostic implications of radioiodine avidity and serum thyroglobulin in differentiated thyroid carcinoma with distant metastasis

Predictive Factors of Radioactive Iodine Therapy Refractoriness in Patients with Differentiated Thyroid Carcinoma

Aim  Differentiated thyroid carcinoma (DTC) is the most prevalent endocrine malignancy, with radioactive iodine (RAI) therapy being a standard of care. However, RAI refractoriness, occurring in a subset of patients, significantly impacts survival rates. Understanding predictive factors for RAI refractoriness is crucial for optimizing patient management. Methods  This retrospective study analyzed data from 90 DTC patients at Ibn Sina University Hospital, Morocco. Patients were categorized into RAI-refractory (RAIR) and non-RAIR groups based on established criteria. Statistical analyses, including univariate and multivariate logistic regression, were performed to identify predictive factors of RAI refractoriness. Results  Age at the time of diagnosis ≥ 54 years, primary tumor diameter ≥ 29 mm, and distal/nodal metastasis were independent predictors of RAIR-DTC. Additionally, the oncocytic carcinoma histological subtype significantly increased the risk of refractoriness. These findings were consistent with previous studies and underscored the importance of early detection and risk stratification. Conclusion  Recognition of predictive factors for RAI refractoriness, including age, tumor size, distal/nodal metastasis, and histological subtype, facilitates early identification of high-risk patients. This enables timely intervention and personalized treatment strategies, particularly relevant in resource-limited settings. Further prospective studies are warranted to validate these findings and explore additional molecular markers for improved prediction of RAI refractoriness.

Strategies for Radioiodine Treatment: What’s New

Radioiodine treatment (RAI) represents the most widespread and effective therapy for differentiated thyroid cancer (DTC). RAI goals encompass ablative (destruction of thyroid remnants, to enhance thyroglobulin predictive value), adjuvant (destruction of microscopic disease to reduce recurrences), and therapeutic (in case of macroscopic iodine avid lesions) purposes, but its use has evolved over time. Randomized trial results have enabled the refinement of RAI indications, moving from a standardized practice to a tailored approach. In most cases, low-risk patients may safely avoid RAI, but where necessary, a simplified protocol, based on lower iodine activities and human recombinant TSH preparation, proved to be just as effective, reducing overtreatment or useless impairment of quality of life. In pediatric DTC, RAI treatments may allow tumor healing even at the advanced stages. Finally, new challenges have arisen with the advancement in redifferentiation protocols, through which RAI still represents a leading therapy, even in former iodine refractory cases. RAI therapy is usually well-tolerated at low activities rates, but some concerns exist concerning higher cumulative doses and long-term outcomes. Despite these achievements, several issues still need to be addressed in terms of RAI indications and protocols, heading toward the RAI strategy of the future.

Scoring system and a simple nomogram for predicting radioiodine refractory differentiated thyroid cancer: a retrospective study

Background

Differentiated thyroid carcinoma (DTC) originates from abnormal follicular cells and accounts for approximately 90–95% of thyroid malignancies. The diagnosis of radioiodine refractory DTC (RR-DTC) is based on clinical evolution and iodine uptake characteristics rather than pathological characteristics. Thus, it takes a long time to become apparent, and the definition of RR-DTC covers multiple aspects. We aimed to analyze the clinical and molecular imaging characteristics of patients with RR-DTC and identify independent predictors to develop an RR-DTC scoring system and a simple nomogram for predicting the probability of RR-DTC. We reviewed the data of 404 patients with metastatic DTC who underwent both post-RAI WB therapy scintigraphy and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography. Data on the clinical features and molecular characteristics of RR-DTC and non-RR-DTC cases were obtained from medical records. We screened for predictors using univariate analyses, obtained independent predictors through multivariate analyses, and then established a scoring system and a simple nomogram for predicting RR-DTC according to the corresponding odds ratio (OR) values.

Results

Diagnosis at age ≥ 48 years (OR, 1.037; 95% confidence interval [CI], 1.007–1.069), recurrence between the operation and iodine-131 treatment (OR, 7.362; 95% CI 2.388–22.698), uptake of ¹⁸F-FDG (OR, 39.534; 95% CI 18.590–84.076), and the metastasis site (OR, 4.365; 95% CI 1.593–11.965) were highly independently associated with RR-DTC. We established a scoring system for predicting RR-DTC, showing that the area under the receiver operating characteristic curve (AUC) with a cutoff value of 10 points (AUC = 0.898) had a higher discernibility than any other single independent predictor. The risk factors of RR-DTC in nomogram modeling include diagnosis at age ≥ 48 years, recurrence between the operation and iodine-131 treatment, uptake of ¹⁸F-FDG, and the site of metastasis. The concordance index (c-Index) of the nomogram was 0.9.

Conclusions

We demonstrated that a predictive model based on four factors has a good ability to predict RR-DTC. An index score ≥ 10 points was found to be the optimal index point for predicting RR-DTC. Moreover, this nomogram model has good predictive ability and stability. This model may help establish an active surveillance or appropriate treatment strategy for RR-DTC cases.

Bone metastases from differentiated thyroid carcinoma: heterogenous tumor response to radioactive Iodine therapy and overall survival

PURPOSE

Bone metastases (BM) from differentiated thyroid carcinoma (DTC) impact negatively the quality of life and the life expectancy of patients. The aim of the study was (a) to evaluate the overall survival (OS) and prognostic factors of OS and (b) to assess predictive factors of complete BM response (C-BM-R) using radioiodine treatment (RAI) either alone or in association with focal treatment modalities.

METHODS

A total of 178 consecutive DTC patients harbouring BM, treated between 1989 and 2015, were enrolled in this retrospective study conducted in two tertiary referral centers. OS analysis was performed for the whole cohort, and only the 145 considered non-RAI refractory patients at BM diagnosis were evaluated for C-BM-R following RAI.

RESULTS

The median OS from BM diagnosis was 57 months (IQR: 24-93). In multivariate analysis, OS was significantly reduced in the case of T4 stage, ¹⁸FDG uptake by the BM and RAI refractory status. Among the 145 DTC considered non-RAI refractory patients at BM diagnosis, 46 patients (31.7%) achieved a C-BM-R following RAI treatment, either alone in 32 (18%) patients or in association with focal BM treatment modalities in 14. The absence of extra-skeletal distant metastasis and of ¹⁸FDG uptake in BM were predictive for C-BM-R.

CONCLUSIONS

In nearly one-third of DTC patients with RAI avid BM, RAI alone or in combination with BM focal treatment can induce C-BM-R. The presence of ¹⁸FDG uptake in BM is associated with an absence of C-BM-R and with a poor OS. ¹⁸FDG PET-CT should be performed when BM is suspected.

EFFECT OF BRAFV600E AND TERT PROMOTER MUTATIONS ON THYROGLOBULIN RESPONSE IN DISTANT-METASTATIC DIFFERENTIATED THYROID CANCER

OBJECTIVE

To assess the impact of BRAF^V600E and telomerase reverse transcriptase (TERT) promoter mutations in distant-metastatic differentiated thyroid cancer (DM-DTC) patients based on thyroglobulin (Tg) response to radioactive iodine (RAI) therapy.

METHODS

BRAF^V600E and TERT mutations in primary tumors or metastatic lymph nodes of 114 DM-DTC patients were retrospectively examined. RAI avidity was evaluated based on posttreatment ¹³¹I-WBS. Tg response was dynamically assessed with a median follow-up of 56.50 months (interquartile range, 28.43-97.98 months).

RESULTS

BRAF^V600E was detected in 38.6% of cases and TERT mutation in 21.1% of cases, and both BRAF^V600E and TERT mutations were observed in 14.9% of cases. Patients with both mutations tended to be older at diagnosis (P<0.001), less multifocal (P=0.011) and have more aggressive histologic subtypes (P=0.011) and a higher Ki-67 index (P=0.003). Patients with neither mutation tended to be more RAI-avid than those with the BRAF^V600E mutant alone or both mutations (P=0.001, <0.001, respectively). Patients with both mutations presented more unfavorable Tg response than those without both mutations and with the BRAF^V600E mutant alone (P=0.001, 0.013, respectively). Tg progression-free survival (Tg-PFS) was shorter in patients with TERT mutation alone than in those with neither mutation (P=0.021), and it tended to be shorter when BRAF^V600E coexisted (P<0.001); however, no significant difference was observed between BRAF^V600E alone and neither mutation (P=0.890).

CONCLUSIONS

Coexistence of BRAF^V600E and TERT promoter mutations synergistically induce loss of RAI avidity and an undesirable Tg response in DM-DTC. TERT promoter mutation appears to affect Tg response more than the BRAF^V600E mutation.

Pre-Therapeutic Measurements of Iodine Avidity in Papillary and Poorly Differentiated Thyroid Cancer Reveal Associations with Thyroglobulin Expression, Histological Variants and Ki-67 Index

Papillary thyroid cancer (PTC) and poorly differentiated thyroid cancer (PDTC) are treated with radioiodine to reduce recurrence and to treat the spread of disease. Adequate iodine accumulation in cancer tissue, iodine avidity, is important for treatment effect. This study investigated which clinical and histological tumour characteristics correlate with avidity. To quantify avidity in cancer tissue, tracer amounts of iodine-131 were given to 45 patients with cytologically confirmed thyroid cancer. At pathology grossing, representative samples of tumour and lymph nodes were taken and subjected to radioactivity quantification ex vivo to determine avidity. Afterwards, samples underwent extended pathology work-up and analysis. We found that tumoural Tg expression and Ki-67 index were correlated with avidity, whereas tumour size and pT stage were not. The histological variant of thyroid cancer was also correlated with iodine avidity. Variants associated with worse clinical prognoses displayed lower avidity than variants with better prognoses. This work provides new information on which tumours have low iodine avidity. Lower avidity in aggressive histological PTC variants may explain their overall poorer prognoses. Our findings also suggest that radioiodine dosage could be adapted to Tg expression, Ki-67 index or histological variant instead of pT stage, potentially improving the efficacy of radioiodine therapy.

Clinical, Pathological, and Molecular Characteristics Correlating to the Occurrence of Radioiodine Refractory Differentiated Thyroid Carcinoma: A Systematic Review and Meta-Analysis

Background: Recently, radioiodine refractory differentiated thyroid cancer (RR-DTC) has received increasing attention due to its poor prognosis. The roles of clinical, pathological, and molecular features in the development of RR-DTC remain controversial and require additional investigation. This study aimed to evaluate the association between these risk factors and the occurrence of RR-DTC.

Methods: We performed a systematic search for relevant literature following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) in PubMed, EMBASE, Medline, SCOPUS, and Web of Science up to the July 15, 2020. Observational studies that investigated the risk factors for RR-DTC were included. Fixed- or random-effects models were used to calculate pooled odds ratios (ORs) or mean differences (MD) with corresponding 95% confidence intervals.

Results: We included 13 eligible studies incorporating 1,431 cases, of which 603 were patients with RR-DTC. The pooled analysis indicated that four parameters significantly increased the risk of RR-DTC: extrathyroidal extension (ETE) (OR: 2.28, 95% CI: 1.43–3.64, I² = 14%), BRAF^V600E mutation (OR: 3.60, 95% CI: 1.74–7.46, I² = 69%), TERT promoter mutation (OR: 9.84, 95% CI: 3.60–26.89, I² = 61%) and high-risk histological subtype (OR: 1.94, 95% CI: 1.15–3.27, I² = 15%), including tall cell variant papillary thyroid carcinoma (PTC), sclerosing diffuse PTC, hobnail variant PTC, follicular thyroid carcinoma (FTC) (including Hürthle cell), and poorly differentiated thyroid carcinoma (PDTC). However, there was no statistical significance regarding sex, age, tumor size, multifocality, or lateral lymph node metastasis. Subgroup and sensitivity analyses were conducted to further confirm the robustness of the results.

Conclusions: Histological subtype, ETE, BRAF^V600E mutation, and TERT promoter mutation could be considered clinicopathological factors and biomarkers. They could assist in risk stratification, prognostic prediction, and individual therapy options for RR-DTC.

Evaluation of the 2015 ATA Guidelines in Patients With Distant Metastatic Differentiated Thyroid Cancer

CONTEXT

Current American Thyroid Association (ATA) Management Guidelines for the treatment of differentiated thyroid cancer (DTC) stratify patients to decide on additional radioiodine (RAI) therapy after surgery, and to predict recurring/persisting disease. However, studies evaluating the detection of distant metastases and how these guidelines perform in patients with distant metastases are scarce.

OBJECTIVE

To evaluate the 2015 ATA Guidelines in DTC patients with respect to 1) the detection of distant metastases, and 2) the accuracy of its Risk Stratification System in patients with distant metastases.

PATIENTS AND MAIN OUTCOME MEASURES

We retrospectively included 83 DTC patients who were diagnosed with distant metastases around the time of initial therapy, and a control population of 472 patients (312 low-risk, 160 intermediate-risk) who did not have a routine indication for RAI therapy. We used the control group to assess the percentage of distant metastases that would have been missed if no RAI therapy was given.

RESULTS

Two hundred forty-six patients had no routine indication for RAI therapy of which 4 (1.6%) had distant metastases. Furthermore, among the 83 patients with distant metastases, 14 patients (17%) had excellent response, while 55 (67%) had structural disease after a median follow-up of 62 months. None of the 14 patients that achieved an excellent response had a recurrence.

CONCLUSIONS

In patients without a routine indication for RAI therapy according to the 2015 ATA Guidelines, distant metastases would initially have been missed in 1.6% of the patients. Furthermore, in patients with distant metastases upon diagnosis, the 2015 ATA Guidelines are an excellent predictor of both persistent disease and recurrence.

Synergic effects of histology subtype, tumor size, and lymph node metastasis on distant metastasis in differentiated thyroid cancer

Background

Detection of distant metastasis (DM) is important in differentiated thyroid cancer (DTC). This study aimed to investigate the synergic effects of histology subtype, tumor size, and lymph node metastasis (LNM) status on the occurrence of DM in DTC.

Methods

We collected data of 96,788 patients with DTC. Univariate and multivariate analyses were conducted to identify the risk factors of DM. Relative excess risk of synergic effect, attributable proportion of synergic effect, and synergy index were then calculated to assess synergic effects. Further, Kaplan-Meier method using the log-rank test and receiver operating characteristic (ROC) curves were utilized.

Results

Age at diagnosis (P<0.001), sex (P<0.001), race (P<0.01), tumor size (P<0.001), N stage (P < 0.001), histology subtype (P<0.001), and extrathyroidal extension (P<0.001) were risk factors for DM in both univariate and multivariate analyses. We also found a significant additive synergic effect between histology subtype and LNM, and between tumor size and LNM on DM in the DTC patients. In addition, patients with follicular thyroid cancer and N1 stage had the sharpest decline in cancer-specific survival curves (P<0.001) and all-cause survival curves (P<0.001) compared to patients with other combinations of histology subtype and N stage. Similar results were obtained in patients with larger tumors (≥10 mm) and N1 stage. The areas under the curve of histology subtype, tumor size, and LNM status were 0.569, 0.744, and 0.681, respectively.

Conclusions

Age at diagnosis, sex, race, tumor size, N stage, histology subtype, and extrathyroidal extension are risk factors for DM in DTC patients. LNM has a synergic effect with either follicular thyroid histology or larger tumor size for higher risk of DM which is important for diagnosing DM.

miR-222 expression is correlated with the ATA risk stratifications in papillary thyroid carcinomas

BACKGROUND

miR-222 is one of the most consistently overexpressed miRNAs in papillary thyroid carcinoma (PTC). Previous studies demonstrated that miR-222 overexpression conferred high-risk features in PTC patients, suggesting its value in risk-stratification. However, studies in term of miR-222's utility on stratifying PTCs are lacking.

METHODS

One hundred patients including 10 with multinodular goiter and 90 with PTC were enrolled. Formalin-fixed paraffin-embedded samples were exploited for miR-222 quantitative reverse transcriptase- polymerase chain reaction (RT-PCR) analysis. Correlations between miR-222 expression and different clinicopathological features, Tumor-node-metastasis (TNM) staging and ATA risk level were analyzed.

RESULTS

miR-222 expression of the PTC group was significantly higher than that of the goiter group (P < .001). Furthermore, miR-222 expression was significantly higher in PTCs with advanced features like larger tumor, capsular invasion, vascular invasion and lymph nodes metastasis. The majority of patients (61%) were in stage I group (similar to ATA low-risk) by TNM staging system. As to the ATA system, the majority (73%) were in intermediate-risk group (similar to TNM stage II and III roughly). Contrary to previous report, here we found that miR-222 expression was correlated with the ATA risk level (P < .001), but not with the TNM staging (P = .122).

CONCLUSION

In the present study, we demonstrated that miR-222 overexpression was correlated with advanced features like capsular invasion, vascular invasion, larger tumor size and lymph node metastasis in PTCs. Most importantly, miR-222 expression was correlated with ATA risk levels, suggesting its potential value in PTC risk-stratification.

Rare Clinical Entity: Metastatic malignant struma ovarii diagnosed during pregnancy - Lessons for management

Background

Malignant struma ovarii is an ovarian teratoma containing at least 50% thyroid tissue which has the potential to metastasize and produce thyroid hormone. Given its rarity, management strategies are not well-established. We report a case of metastatic malignant struma ovarii discovered during pregnancy with lessons for evaluation and management.

Case presentation

A 30-year-old woman who was two months pregnant was discovered to have struma ovarii with over half of the struma comprised of papillary thyroid cancer. Following tumor resection, delivery, and thyroidectomy, she underwent evaluation with stimulated thyroglobulin testing and diagnostic staging sodium iodide-131 scan (I-131), which revealed the presence of skeletal metastases. Following administration of 320 mCi I-131, post-therapy scan also showed miliary pulmonary metastases with improved ability to localize the bony and pulmonary metastases with concurrent SPECT/CT imaging. A second dosimetry-guided I-131 therapy resulted in complete resolution of pulmonary metastases; however, small foci of residual bone disease persisted. Post-therapy scans demonstrated additional findings not shown on diagnostic I-131 scans obtained prior to both her initial and second I-131 therapy.

Conclusions

SPECT/CT provides accurate anatomic correlation and localization of metastatic foci and can serve as a baseline study to assess interval response to treatment. Post-therapy scans should always be obtained when I-131 treatment is administered, as additional findings may be revealed versus low dose I-131 activity diagnostic scans. This patient had a high metastatic burden that would not have been discovered in a timely fashion with the conservative approach advocated by others. Thyroidectomy followed by a diagnostic staging radioiodine scan and a stimulated thyroglobulin level should be considered in patients with malignant struma ovarii for guiding therapeutic I-131 administration as metastatic risk is difficult to predict based on histopathologic examination.

Quantitative thyroglobulin response to radioactive iodine treatment in predicting radioactive iodine-refractory thyroid cancer with pulmonary metastasis

OBJECTIVE

Current diagnosis of radioactive iodine (RAI)-refractory (RAIR) differentiated thyroid cancer (DTC) is based on the imaging technique, which is of a high cost. Serum thyroglobulin (Tg) is a sensitive and easily obtained biomarker. Hence, we aimed to assess the predicting value of quantitative response of Tg in earlier identifying the RAIR-DTC with pulmonary metastasis.

PATIENTS AND METHODS

Pulmonary metastatic DTC patients who underwent total or near-total thyroidectomy and at least two times of RAI therapy were included in this study. The pre-ablative stimulated Tg at the first and second RAI therapy were defined as pstim-Tg1 and pstim-Tg2, while the suppressed Tg before and after the second RAI therapy were designated sup-Tg1 and sup-Tg2. The predicted value of pstim-Tg2/Tg1 and sup-Tg2/Tg1 ratio were detected using the receiver operating characteristic (ROC) curve and logistic regression analyses.

RESULTS

Totally 115 patients were involved in this study. ROC curves showed a cut-off value of 0.544 for pstim-Tg2/ pstim-Tg1 in detecting RAIR, with a sensitivity of 0.9 and specificity of 0.477, and an area under the curve (AUC) of 0.744. Similarly, the cut-off of sup-Tg2/ sup-Tg1 was 0.972, with a sensitivity of 0.733 and specificity of 0.935, and AUC of 0.898. Univariate analysis illustrated that age, tumor size, pstim-Tg2/Tg1, sup-Tg2/ sup-Tg1 and BRAFV600E mutation were eligible to predict RAIR. While from multivariate analysis, only age, pstim-Tg2/Tg1, sup-Tg2/ sup-Tg1 and BRAFV600E mutation were verified to be the independent predictive factors.

CONCLUSION

The quantitative Tg response was encouraging in identifying RAIR-DTC with pulmonary metastasis. Age, BRAFV600E mutation and Tg response were independent predictors in predicting RAIR-DTC.

Primary Thyroid Carcinoma with Low-Risk Histology and Distant Metastases: Clinicopathologic and Molecular Characteristics

BACKGROUND

Distant metastases (DM) are a rare occurrence in well-differentiated thyroid carcinoma. The aim of this study was to analyze the clinical, pathologic, and molecular features of primary thyroid carcinoma with low-risk histology that develop DM.

METHODS

A detailed clinicopathologic review and targeted next-generation sequencing were performed on a cohort of well-differentiated thyroid carcinoma lacking gross extrathyroidal extension, extensive vascular invasion, or significant lymph node metastases but exhibiting DM.

RESULTS

Primary well-differentiated thyroid carcinoma with low-risk histologic features and DM was a rare occurrence, accounting for only 3% of metastatic non-anaplastic thyroid carcinoma. All 15 cases meeting the inclusion criteria harbored DM at presentation. The majority (11/15) of these tumors were follicular variant of papillary thyroid carcinoma (PTC), especially the encapsulated form (n = 8). The remaining patients harbored encapsulated Hürthle cell carcinoma (n = 2), encapsulated follicular carcinoma (n = 1), and an encapsulated papillary carcinoma classical variant (n = 1). Of the 12 encapsulated carcinomas, 10 had capsular invasion only and no vascular invasion. Ninety-two percent of the tumors exhibited extensive intra-tumoral fibrosis. Among the eight tumors that were subjected to next-generation sequencing analysis, a RAS mutation was the main driver (5/8), and TERT promoter mutation was highly prevalent (6/8). In four cases, TERT promoter mutations were associated with RAS or BRAF mutations. BRAF-mutated classical variant of papillary carcinoma also presented with DM but was less common (1/8). In 11/15 cases, the clinician was able to diagnose distant disease based on the clinical presentation. In 3/4 incidental cases that were genotyped, TERT promoter mutations were found.

CONCLUSIONS

When DM occur in primary thyroid carcinoma with low-risk histology, they are almost always found at presentation. The majority are encapsulated follicular variant of PTC with capsular invasion only. TERT promoter mutations occur at a higher rate than that seen in PTC in general and may help explain the aggressive behavior of these histologically deceptive primary carcinomas.

Early prognostic factors at the time of diagnosis of bone metastasis in patients with bone metastases of differentiated thyroid carcinoma

OBJECTIVE

Bone is the second most common site of distant metastases from differentiated thyroid cancer (DTC). Patients with bone metastases were associated with poor clinical outcomes; however, their clinical courses are heterogeneous. The aim of this study is to evaluate early prognostic factors of patients with bone metastases from DTC at the time of diagnosis of bone metastasis.

METHODS

This retrospective study included 93 patients with bone metastases from DTC. We defined 'Pre-RAIT group' as patients whose bone metastases were detected before initial RAIT. The 'post-RAIT group' was defined as patients whose bone metastases were detected after initial RAIT or during the follow-up period.

RESULTS

Median age was 55.4years, and 55 patients (59%) had papillary thyroid cancer. Patients in the pre-RAIT group (n=32) demonstrated significantly poorer overall survival (OS) (HR=1.86, P=0.04) than those in the post-RAIT group. There was no significant difference in the OS according to the initial RAI avidity among all patients (P=0.18). RAI-avid bone metastases had better OS only in the pre-RAIT group (HR=0.23, P=0.01) but not in the post-RAIT group. In the post-RAIT group, older age (>45years), elevated serum thyroglobulin (Tg) level (>250ng/mL), and the presence of skeletal-related events (SREs) were significantly associated with poor OS. RAI avidity was not a significant prognostic factor in the post-RAIT group (P=0.33).

CONCLUSIONS

Patients whose bone metastases were diagnosed before initial RAIT demonstrate a poorer prognosis. RAI avidity is an early prognostic indicator in the pre-RAIT group. Old age, higher serum Tg levels, and SRE are associated with poor survival outcomes in the post-RAIT group.

Outcomes and Prognostic Factors in Radioiodine Refractory Differentiated Thyroid Carcinomas

BACKGROUND

Outcomes vary among patients with radioiodine refractory (RR) differentiated thyroid cancer (DTC). The prognostic factors for survival are not well-known, resulting in difficulty in selecting patients for new targeted therapies. We assessed overall survival (OS) and cancer-specific survival (CSS) from RR-DTC to identify prognostic factors associated with survival.

PATIENTS AND METHODS

The data on all cases of metastatic RR-DTC treated in our center from 1990 to 2011 were retrospectively reviewed. Survival was estimated using the Kaplan-Meier method; associated prognostic factors were assessed using Cox's model.

RESULTS

Of 153 cases of metastatic DTC, 59% (n = 91) met a criterion for RR: that is, 60% (n = 55) had at least 1 metastasis without (131)I uptake; 21% (n = 19) had progressive disease (PD) despite (131)I; 19% (n = 17) had persistent disease despite a cumulative activity of (131)I of ≥600 mCi. After the diagnosis of RR, median OS was 8.9 years (95% confidence interval [CI]: 5.4-NR); median CSS was 9.6 years (95% CI: 6.01-NR). In multivariate analyses, PD despite (131)I as a criterion for RR disease and the time from initial diagnosis of DTC to diagnosis of RR <3 years were the only independent prognostic factors for poor OS and CSS. Thyroglobulin doubling time (Tg-DT) was assessed in 31 of 91 cases. Among the 11 patients with Tg-DT for <1 year or undetectable Tg, 6 deaths occurred, whereas only 3 died of 20 patients with Tg-DT >1 year or negative Tg-DT.

CONCLUSION

The identification of prognostic factors for decreased survival in RR-DTC may improve the selection of patients for targeted agents.

IMPLICATIONS FOR PRACTICE

This study shows a great heterogeneity in terms of prognosis in radioiodine refractory differentiated thyroid carcinoma. Poorer prognosis is observed in patients with tumor progression or with a diagnosis of radioiodine resistance within 3 years after the initial diagnosis of thyroid cancer. Those findings could lead to improvements in the selection of patients for targeted therapies.

Radioiodine Scan Index: A Simplified, Quantitative Treatment Response Parameter for Metastatic Thyroid Carcinoma

PURPOSE

We aimed to develop and validate a simplified, novel quantification method for radioiodine whole-body scans (WBSs) as a predictor for the treatment response in differentiated thyroid carcinoma (DTC) patients with distant metastasis.

METHODS

We retrospectively reviewed serial WBSs after radioiodine treatment from 2008 to 2011 in patients with metastatic DTC. For standardization of TSH simulation, only a subset of patients whose TSH level was fully enhanced (TSH > 80 mU/l) was enrolled. The radioiodine scan index (RSI) was calculated by the ratio of tumor-to-brain uptake. We compared correlations between the RSI and TSH-stimulated serum thyroglobulin (TSH_s_Tg) level and between the RSI and Tg reduction rate of consecutive radioiodine treatments.

RESULTS

A total of 30 rounds of radioiodine treatment for 15 patients were eligible. Tumor histology was 11 papillary and 4 follicular subtypes. The TSH_s_Tg level was mean 980 ng/ml (range, 0.5-11,244). The Tg reduction rate after treatment was a mean of -7 % (range, -90 %-210 %). Mean RSI was 3.02 (range, 0.40-10.97). RSI was positively correlated with the TSH_s_Tg level (R(2) = 0.3084, p = 0.001) and negatively correlated with the Tg reduction rate (R(2) = 0.2993, p = 0.037). The regression equation to predict treatment response was as follows: Tg reduction rate = -14.581 × RSI + 51.183.

CONCLUSIONS

Use of the radioiodine scan index derived from conventional WBS is feasible to reflect the serum Tg level in patients with metastatic DTC, and it may be useful for predicting the biologic treatment response after radioiodine treatment.

Recurrent thyroid cancers have more peritumoural lymphatic vasculature than nonrecurrent thyroid cancers

BACKGROUND

The goal of the study was to evaluate angiogenesis and lymphangiogenesis in differentiated thyroid cancer and recurrences.

METHODS

Twenty-seven patients with recurrent differentiated thyroid cancer (20 papillary and seven follicular thyroid carcinomas) and 24 nonrecurrent thyroid cancers were included in this study. Additionally, 24 thyroid adenomas were included as benign controls. All thyroid cancer recurrences were operatively managed, and local recurrences in cervical lymph nodes or cervical soft tissue were histologically confirmed. Altogether, a total of 108 samples were evaluated using CD31 and D2-40 immunohistochemical staining and microscopy.

RESULTS

As measured in primary tumours, the median density of CD31-positive vascular structures was 327 vessels (v)/mm(2) for recurrent cancers, 362 v/mm(2) for nonrecurrent cancers and 484 v/mm(2) for thyroid adenomas (P = 0·017). Among the subgroups, the lowest median vascular density of 316 v/mm(2) was found in recurrent papillary cancers and the highest vascular density of 604 v/mm(2) was observed in nonrecurrent follicular cancers (P = 0·018). The median density of D2-40-positive peritumoural lymphatic vessels was 101/mm(2) in recurrent cancers, 56·1/mm(2) in nonrecurrent cancers and 53·9/mm(2) for adenomas (P = 0·015). In the subgroups, peritumoural lymphatic vascular density was 102 v/mm(2) in recurrent papillary cancers and 56·0 v/mm(2) in nonrecurrent papillary cancers (P = 0·044).

CONCLUSIONS

Recurrent thyroid cancers expressed less intratumoural microvessels than thyroid adenomas. A high density of peritumoural lymphatic vessels was found in recurrent papillary cancers. High blood vessel density may be a marker for less aggressive tumours, while high peritumoural lymphatic vasculature is a marker for more aggressive and recurrence-prone tumours.