The changing role of radioiodine in the management of differentiated thyroid cancer

Advanced esophageal cancer with bone metastases: Prognostic biomarkers and palliative treatment

Esophageal cancer (EC) is a common and devastating tumor of the upper digestive tract. Unfortunately, by the time any symptoms have manifested, the disease has often progressed to an advanced stage and is accompanied by macro- and micrometastases, including in the bones. The treatment of esophageal cancer with bone metastases remains clinically challenging, given the poor prognosis associated with this condition. Effective prognostic biomarkers can help medical staff choose the appropriate operation and treatment plan, that is for most beneficial for making patients. Current treatments for esophageal cancer with bone metastases include pain-relieving drugs, surgical therapy, radiotherapy (RT), chemotherapy (CT, including molecular-targeted drug therapy), endocrine therapy (ET), bisphosphonates (BPs) and interventional therapy. Of these robust measures, radiotherapy has emerged as a particularly promising therapy for bone metastases from esophageal cancer. Substantial progress has been made in radiation therapy techniques since the discovery of X-rays by Roentgen in 1895. In its palliative capacity, the key goals of radiotherapy are to relieve the patients' bone pain and debilitate effects, including relieving spinal cord compression, correcting the spinal deformity and restoring spinal stability. However, it is worth mentioning that RT for esophageal cancer has various side effects. Currently, the available studies focused exclusively on radiotherapy for ECBM are too small to draw any definitive conclusions, and each of these studies has significant limitations. In this review, in addition to the epidemiology described at the beginning, we will explore the current prognostic biomarkers and radiotherapy for esophageal cancer, with a particular focus on those with bone metastases.

Radiopharmaceuticals: A New Vista for Diagnosis and Treatment of Thyroid Cancer

Radiopharmaceuticals are in the diagnosis and treatment of cancerous and noncancerous diseases, and a hope for optimistic effort in the field of nuclear medicine. They play a crucial role in clinical nuclear medicine by providing a tool to comprehend human disease and create efficient treatments. A detailed analysis is provided regarding the crux of molecular imaging including PET and SPECT overview for the detection of cancers. For a specified understanding of radiation therapy, topics include ranging from the selection of radionuclide to its development and manufacture, and dosage requirements to establishing the importance of I- 131 Radiotherapy in thyroid cancer. In this review, we also discussed the current state of the art of nuclear medicine in thyroid cancer, including the role of radioiodine (RAI) therapeutic scans in the diagnosis of differentiated thyroid cancer. In addition, we established a brief outlook into the current status of the research in thyroid cancer and discussed the future directions in this field.

Thyroid stunning in radioiodine-131 therapy of benign thyroid diseases

PURPOSE

Existence and cause of thyroid stunning was controversially discussed for decades but the underlying mechanism remains unclear. Numerous studies describe thyroid stunning in radioiodine-131 therapy (RIT) of differentiated thyroid carcinoma. However, there are no studies evaluating thyroid stunning in benign thyroid diseases caused by the radioiodine uptake test (RIUT). Therefore, the influence of pre-therapeutic tracer radiation dose on therapeutic iodine-131 uptake was evaluated retrospectively.

METHODS

A total of 914 RIT patients were included. Exclusion criteria were anti-thyroid drugs, pre- and/or intra-therapeutic effective half-lives (EHL) beyond 8.04 days and externally performed RIUT or 24 h RIUT. All patients received RIUT 1 week before RIT. Thyroid volume was estimated via ultrasound. Tracer radiation dose to the thyroid was calculated retrospectively. The dependence of changes in the pre-therapeutic to the therapeutic extrapolated-maximum-¹³¹I-uptake (EMU) from the dose in RIUT was evaluated statistically.

RESULTS

EMU in RIUT ranged from 0.10 to 0.82 (median: 0.35) and EMU in RIT ranged from 0.10 to 0.74 (median: 0.33). Averaged over the whole cohort the therapeutic EMU decreased significantly (2.3% per Gray intra-thyroidal tracer radiation dose). A disease-specific evaluation showed dose-dependent thyroid stunning from 1.2% per Gray in solitary toxic nodules (n = 327) to 21% per Gray in goiters (n = 135) which was significant for the subgroups of disseminated autonomies (n = 114), multifocal autonomies (n = 178) and goiters (p < 0.05) but not for Graves' diseases (n = 160) and solitary toxic nodules (p > 0.05).

CONCLUSIONS

The presented data indicate for the first time a significant dependence of pre-therapeutic radiation dose on thyroid stunning in goiter and disseminated and multifocal autonomy. To achieve the desired intra-thyroidal radiation dose, RIT activity should be adapted depending on the dose in RIUT.

A Clinical Trial of Optimal Time Interval Between Ablation and Diagnostic Activity When a Pretherapy RAI Scanning Is Performed on Patients With Differentiated Thyroid Carcinoma

This article investigates the association of the time interval between the diagnostic dose and ablation with the stunning effect, when a 74 MBq I pretherapy scanning was performed on patients with differentiated thyroid carcinoma (DTC); the patients who were diagnosed as DTC and would be performed radioiodine (RAI) ablation of thyroid remnants or metastases were recruited during January 2011 and May 2012 in our hospital.Thirty-seven patients with DTC who had the RAI ablation of thyroid remnants or metastases for the first time were recruited. All the patients received a dose of 1850 to 7400 MBq of I for ablation and a diagnostic scan was performed 24 hours after the administration of 74 MBq I before ablation. A posttherapy scan was performed 2 to 7 days after the ablation. The patients were broken down into 3 groups (G1, G2, and G3) according to the interval time between the diagnostic dose and therapy (1-3, 4-7, and >7 days). The fractional concentrations of I in remnants or functional metastases were quantified and expressed as therapeutic/diagnostic (Rx/Dx). The level of significance was set at 0.05.Sixty-seven foci were found both on pretherapy and posttherapy scans, the mean ratio of Rx/Dx was 0.43 ± 0.29, and the ratio of 49 foci (73.13%) was <0.6. The ratios in G1, G2, and G3 were 0.46 ± 0.29, 0.29 ± 0.18, and 0.55 ± 0.33, respectively. The differences between G1 and G2, and G2 and G3 were statistically significant (t = 2.40, P = 0.021 and t = 3.28, P = 0.002), whereas the difference between G1 and G3 was not significant (t = 1.01, P = 0.319).By a diagnostic scan of 74 MBq I, stunning prominently occurs with a time of 4 to 7 days between the diagnostic dose and ablation. We recommend that for less stunning effect, RAI ablation should be performed within 3 days or postponed until 1 week after the diagnostic dose administrated.

Laparoscopic partial nephrectomy of thyroid cancer metastasis: case report and review of the literature

Background

Follicular cell thyroid carcinoma is a quite aggressive form of thyroid cancer. About 10% of follicular thyroid carcinoma shows multiple metastases: lung and bone are the most common sites of metastasis. Renal involvement from thyroid primary cancer is very rare with incidence of 4.5%–5.9%.

Purpose

We report the first laparoscopic conservative treatment of renal metastasis from thyroid cancer. This is a new and useful approach in order to delay malignant disease progression and to reduce the surgical discomfort of the patient.

Patients and methods

We present the case of a 67-year-old woman, undergoing total thyroidectomy for follicular thyroid cancer with bone and lung metastasis. During adjuvant radiometabolic treatment, renal metastasis was diagnosed. Renal metastasis showed high metabolic activity, reducing the effectiveness of radioiodine therapy for secondary lesions. For this reason, we performed a laparoscopic simple enucleation of the single renal metastasis using extraperitoneal access and a clampless procedure.

Results

The excision of the renal lesion improved the effectiveness of adjuvant radioiodine therapy: two months after surgery, the patient underwent adjuvant radiometabolic treatment with iodine-131 (150 mCi) and the following whole body scan showed only a small uptaking area at the level of the vertebral metastasis. The lung micrometastases were not detectable. At 36 months follow-up, malignant disease was clinically stable and well controlled.

Conclusion

Minimally invasive renal surgery with preservation of renal function and rapid recovery contributed to the success of radioiodine therapy and delayed the progression of the disease.

An individualized approach to the child with thyroid cancer

Children with differentiated thyroid cancer (DTC) often present with extensive disease that inclined clinicians in prior decades toward aggressive treatment including total thyroidectomy, radical neck dissection and universal prescription of radioactive iodine (RAI). Recent series with 40 years of follow-up have shown that fewer than 2% of children ultimately die from DTC, but they may have increased all-cause mortality from second malignancies that might be related to previous radiation exposure. In this article, we review data to support the notion that an individualized, risk-stratified approach to therapy should be used for children with DTC. Ideally this will provide aggressive therapy for those in whom aggressive treatment is warranted, but withhold aggressive and risk-associated therapy from those who are not likely to benefit.

DNA double-strand breaks induced by decay of (123)I-labeled Hoechst 33342: role of DNA topology

PURPOSE

To determine double-strand-break (DSB) yields produced by decay of minor-groove-bound (123)I-labeled Hoechst 33342 ((123)IEH) in supercoiled (SC) and linear (L) forms of pUC19 DNA, to compare strand-break efficiency of (123)IEH with that of (125)IEH, and to examine the role of DNA topology in DSB induction by these Auger electron emitters.

MATERIALS AND METHODS

Tritium-labeled SC and L pUC19 DNA were incubated with (123)IEH (0-10.9 MBq) at 4 degrees C. After (123)I had completely decayed (10 days), samples were analyzed on agarose gel, and single-strand-break (SSB) and DSB yields were measured.

RESULTS

Each (123)I decay in SC DNA produces a DSB yield of 0.18 +/- 0.01. On the basis of DSB yields for (125)IEH (0.52 +/- 0.02 for SC and 1.62 +/- 0.07 for L, reported previously) and dosimetric expectations, a DSB yield of approximately 0.5 (3 x 0.18) per (123)I decay is expected for L DNA. However, no DSB are observed for the L form, even after approximately 2 x 10(11) decays of (123)I per microg DNA, whereas a similar number of (125)I decays produces DSB in approximately 40% of L DNA.

CONCLUSION

(123)IEH-induced DSB yield for SC but not L DNA is consistent with the dosimetric expectations for Auger electron emitters. These studies highlight the role of DNA topology in DSB production by Auger emitters and underscore the failure of current theoretical dosimetric methods per se to predict the magnitude of DSB.

Utility of a low-iodide diet in (131)I whole body scanning of patients with differentiated thyroid cancer

INTRODUCTION

(131)I whole body scanning (WBS) is useful in the follow-up of patients with differentiated thyroid carcinoma (DTC). The need to follow a low-iodide diet (LID) to optimize WBS is widely recognized but there are few reports that justify this practice. The aim of this study was to assess levels of urinary iodide in patients who underwent WBS in our service and the possible impact of some changes to the diet on these levels.

PATIENTS AND METHOD

Between January 2004 and December 2005, we measured iodide levels in 12-h urine samples by paired-ion-reversed-phase HPLC with electrochemical detection (sensitivity, 0.1 μg/dl) in 371 patients with DTC referred to our service for ablation or follow-up. The patients were divided into 2 groups: patients on hormone withdrawal and strict LID (group A) and those on hormone withdrawal and generic LID (group B). Urinary iodide excretion below 10 μg/dl was considered low. Data were analyzed by ANOVA and χ(2) tests.

RESULTS

The mean±standard deviation urinary iodide excretion was 4.3±3 μg/dl in group A and 5.8±3.2 μg/dl in group B. The mean urinary iodide excretion in A group was significantly lower than that in group B (p<0.05).

CONCLUSIONS

Following a strict LID significantly decreased urinary iodide excretion in patients undergoing WBS.

Evaluation of the Cell Death Pathway and Apoptosis-Stunning Effect Relationship After Low- and High-Dose I-131 Administrations in Rat Thyroid Tissue

OBJECTIVES

This study had two aims; (1) to describe the cell death pathway (apoptosis or necrosis) induced by a low and high dose of radioiodine (I-131) in rat thyroid tissue in in vivo conditions and (2) to determine the role of apoptosis in the development of "stunning effect" in the thyroid tissue with low and high doses of I-131 application.

DESIGN

The experimental group consisted of 18 rats; low and high I- 131 doses with a 1-week interval were administered to this group. At first, low doses were injected intraperitoneally (i.p.) (net injected dose was 51.54 +/- 8.6 microCi). After 1 week of the low-dose injection, high doses were also injected (net injected dose was 934.9 +/- 211.8 microCi). Thyroidal I-131 uptakes for both low- and high-dose applications were calculated by using a gamma camera after 24 hours of injections. Immediately after the uptake calculation, thyroid tissues were resected. A control group of 10 rats was also included in the study; in this group, I-131 was not administered. Thyroid tissues of this group rats were also resected. DNA was extracted from thyroid tissues, and damage was examined with the "DNA ladder by agaroz gel electrophoresis."

RESULTS

Thyroidal I-131 uptakes were calculated as 11.3% +/- 3.6% and 9.8% +/- 5.3% at the 24th hour after low- and high-dose I-131 applications, respectively. When the low- and high-dose uptake values were compared for each rat; a significant relationship was not found between thyroidal uptakes and injected low and high doses of I-131. When the chromosome images were examined, there was healthy DNA appearance in 1 rat; in 4 rats, only necrotic hyperfragmentations were observed; in 9 rats, both apoptotic specific fragmentations and necrotic hyperfragmentations were observed; and in 4 rats, apoptosis, necrosis, and healthy DNA appearances were seen together. In none of the rats, specific fragmentations concordant only with apoptosis was found. When the thyroidal uptake alterations were taken into consideration, significant difference was not found between first and second uptake calculations (p = 0.28). No significant relationship was also observed between thyroidal uptake alterations and apoptosis-necrosis-healthy DNA findings. Additionally, when we take into consideration the DNA results of only 13 of the rats that had reduced thyroidal uptake, a significant relationship could also not be observed between reduced uptake and apoptotic, necrotic, or healthy tissue findings. Interestingly, apoptotic and necrotic tissue or only necrotic, tissue findings were observed in the other 5 rats which had increased thyroidal uptake.

CONCLUSIONS

Following I-131 administration, two types of cell death--both apoptosis and necrosis findings--have been observed in most of the rats. We think that the decreased uptake values are because of the probable stunning effect in thyroid tissue. We also investigated whether the stunning effect is related to apoptosis. According to our results, it can be concluded that the stunning effect is not related to tissue damage, cell decrease, or cell death. Alternatively, we think that this can be related to a radiation-induced reduction of iodine uptake/metabolism or a modified iodine transport mechanism. For further in vivo studies, this experimental model using normal rat thyroid tissue may be useful in investigating the cell death pathways induced by I-131 and its probable roles in the development of the stunning phenomenon.

Evaluation of the p53 tumor suppressor gene mutation in normal rat salivary gland tissue after radioiodine application: an experimental study

In this experimental study, investigators explored p53 tumor suppressor gene mutation induced by low and high doses of iodine-131 sodium iodide (I-131) in salivary gland tissue in rats. Group 1 consisted of 10 rats; low and high I-131 doses were applied at a 1-wk interval. First,low doses of I-131 were injected. (The net injected dose was 47.5-/+9.2 microCi.) After 1 wk, high doses of I-131 were also injected. (The net injected dose was 1007.2-/+53 microCi.) Group 2 consisted of 5 rats, and only a low I-131 dose was applied. (The net injected dose was 52.7-/+5.5 microCi.) The Control Group consisted of 5 rats that did not receive I-131. Thyroidal I-131 uptakes were calculated for Groups 1 and 2 with the use of a gamma camera after 24 h of injections. Immediately after uptake was calculated, salivary glands were resected in all groups and DNA was extracted for genotyping. Genomic DNA of the p53 gene exon 5 was examined by polymerase chain reaction single-strand conformational polymorphism. In Group 1, thyroidal I-131 uptakes were calculated as 12.45%-/+4.14% and 9.66%-/+6.73% after low-dose and high-dose I-131 applications, respectively. In Group 2, thyroidal I-131 uptake was calculated as 13.12%-/+3.04%. In Group 1, p53 gene abnormality was seen in the salivary gland of only 1 of the rats. Double- and single-strand gene profiles showed that both alleles of this rat have a mutated single-strand conformational polymorphism profile of point mutation in the p53 gene exon 5. This rat received the highest low dose and the second highest total dose of I-131; its thyroidal uptakes were the second highest. In the other rats in Group 1, and in Group 2 and the Control Group, p53 gene abnormalities were not observed. In Groups 1 and 2, a significant relationship could not be discerned between thyroidal uptake of I-131 and p53 gene mutation in the salivary gland. No significant relationship was observed between thyroidal uptake alterations and p53 gene mutations in salivary glands in Group 1. A point mutation in the p53 gene exon 5 that was seen in only 1 of the rats in Group 1 seems related to the high-dose application of I-131, although coincidental occurrences could not be excluded. We believe that this topic is open to additional in vivo studies.

Adrenal and renal metastases from follicular thyroid cancer

Patients with differentiated thyroid cancer may have asymptomatic involvement of renal and/or adrenal gland, particularly if they are elderly and have associated metastases to other organs, which may remain undetected if these patients are not subjected to radioiodine treatment. Our experience also emphasises the role of routine post-radioiodine therapy whole body scan with high degree of clinical suspicion, which may reveal lesions otherwise not discernable in low dose whole body scan. All suspicious lesions should be subjected to structural imaging like ultrasound, CT or MRI for confirmation. In this setting, the role of radioiodine therapy is primarily aimed at palliation that might prolong their survival, probably reduce further spread and thus overall improve the quality of life.

I-131 therapy for thyroglobulin positive patients without anatomical evidence of persistent disease

OBJECTIVE

the aim of this retrospective study was to evaluate the diagnostic relevance of I-131 whole body scan (WBS) performed after second empirical therapeutic doses of iodine-131 (I-131) in thyroglobulin (Tg)-positive thyroid cancer patients without evidence of local and distant metastasis. We also evaluated the efficacy of second empirical therapeutic doses of I-131 in these patients.

METHODS

we retrospectively compared the results of diagnostic I-131 WBS and post-therapy scans of second therapeutic doses of I-131 in 38 patients with detectable Tg while off T4 therapy (TSH>25 mlU/ml). All patients underwent a near-total or total thyroidectomy and I-131 ablation with 75-125 mCi. All of the reported subjects had no prior evidence for detectable disease before second high dose empirical I-131 therapy.

RESULTS

there was almost complete concordance in uptake between diagnostic I-131 WBS and final scans carried out after second I-131 therapy in 22 out of 38 patients. Whereas abnormal foci of new uptake was detected in all of the remaining 16 patients, seven of them were found to have negative diagnostic WBS results. Distant metastases were observed in 3 of 16 subjects and mediastinal uptake was found in 2 of 16 patients in post-therapy scan. During the subsequent follow-up, extending from 8-46 months, 6 out of 16 patients showed normalization of serum Tg levels while off T4. Serum Tg levels were normalized in 3 out of 7 patients who had negative WBS results, increased in one and unchanged in the remaining 3. None of the patients with distant metastases had normalization of Tg levels. Totally, 6 out of 38 showed normalization of Tg levels while off T4 therapy.

CONCLUSION

the empirical therapeutic doses of 1-131 may help in localization of the disease in Tg positive patients without anatomical evidence of persistent disease, but the effect of I-131 therapy on long-term survival is not obvious.

Cognitive changes in short-term hypothyroidism assessed with event-related brain potentials

Hypothyroidism is a common clinical problem during (131)Iodine-therapy of thyroid cancer. In the present investigation, possible cognitive dysfunction during hypothyroid state was assessed by means of neuropsychological tests and the recording of event-related brain potentials (ERPs). Fifteen patients undergoing therapy for thyroid cancer were examined twice: (1) substituted with thyroid hormones, (2) during hypothyroid state immediately prior to treatment. Standard neuropsychological tests were applied during both sessions and subjects showed a mild-to-moderate impairment in their hypothyroid state. In addition, ERPs were recorded from 19 scalp sites while subjects performed two visual search tasks. The serial task required the effortful one-by-one scanning of several items within a visual array, while the parallel task allowed processing of all stimulus items in parallel and automatically. ERPs showed a marked amplitude decrement and delay of the P3 component known to index the speed of stimulus evaluation and the amount of available processing resources. This effect was present only for the serial search task, while no changes were seen in the parallel search task. These data show that hypothyroidism during (131)Iodine-therapy is associated with clinically relevant cognitive dysfunctions, especially with effortful attention demanding tasks.

131I Therapeutic Efficacy Is Not Influenced by Stunning after Diagnostic Whole-Body Scanning

PURPOSE

To determine if stunning can be seen with a 185-MBq (5-mCi) dose of iodine 131 (131I) at diagnostic whole-body scanning and, if stunning is seen, determine if there is any 131I therapeutic efficacy.

MATERIALS AND METHODS

A retrospective review of findings involving 166 patients who underwent thyroidectomy for differentiated thyroid carcinoma was performed. Diagnostic 131I scans were compared with postablation scans for evidence of stunning. Stunning was defined when the diagnostic scan showed activity that was subsequently decreased on the postablation scan. The sample population was divided into two groups: group NS, patients with no stunning, and group S, patients with stunning. Patients were considered successfully treated if no functioning thyroid tissue and/or metastases were seen on follow-up diagnostic scans. Fisher exact and Student t tests were used to evaluate the statistical significance of therapy success rates, clinical characteristics, and scanning parameters between the two groups.

RESULTS

Group NS included 135 (81.3%) of 166 patients, with 36 (26.7%) of 135 lost to follow-up. Group S included 31 (18.7%) of 166 patients, with eight (26%) of 31 patients lost to follow-up. There was no significant difference (P =.61) in treatment success rates between group NS (87 of 99, 88%) and group S (21 of 23, 91%). The treatment success rates for thyroid remnants were 87% (48 of 55) for group NS and 91% (10 of 11) for group S (P =.63). Treatment success rates for metastases (mostly lymph nodes) were 89% (39 of 44) for group NS and 83% (10 of 12) for group S (P =.55).

CONCLUSION

Thyroid stunning can occur with 185 MBq of 131I in diagnostic imaging. However, data did not show any effect of stunning on the efficacy of 131I therapy for differentiated thyroid carcinoma.

In-111 DTPA-octreotide scintigraphy for disease detection in metastatic thyroid cancer: comparison with F-18 FDG positron emission tomography and extensive conventional radiographic imaging

PURPOSE

The utility of In-111 DTPA octreotide scintigraphy (SRS) for disease detection in patients with metastatic thyroid carcinoma (TCA) remains controversial. The authors compared the sensitivity of In-111-based SRS, F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET), and extensive conventional radiographic imaging (CRI) in this type of cancer.

METHODS

SRS, FDG PET, and CRI were performed concurrently in 21 patients (age, 56.4 +/- 12.9 years) who had aggressive TCA. Concordance rates % of lesion positivity among pairs of different techniques (A and B) were calculated as the ratio of the number of lesions positive with both techniques divided by the sum of the total number of lesions positive with technique A + total number of lesions positive with technique B, which was then multiplied by 200.

RESULTS

The combined use of CRI, FDG PET, and SRS resulted in the detection of 105 lesions, presumed to be due to metastatic deposits. Sensitivities for SRS and FDG-PET imaging were 49.5% and 67.6%, respectively. The lesion detection concordance rates were as follows: CRI versus FDG PET, 80.8%; CRI versus SRS, 74.2%; and FDG-PET versus SRS, 58.6%. Importantly, SRS detected five unexpected lesions, which were negative by both CRI and FDG-PET imaging. In two representative patients, a positive correlation (Spearman's rank = 0.71; = 0.0576) existed between the percentage of lesional In-111 DTPA octreotide uptake and the standard uptake value in eight concordant lesions.

CONCLUSION

Although SRS has only moderate sensitivity for disease detection in metastatic TCA, sometimes it can reveal lesions that otherwise would be undetectable by either CRI or FDG-PET imaging.

Current controversies in the management of pediatric patients with well-differentiated nonmedullary thyroid cancer: a review

Current treatment strategies for pediatric patients with nonmedullary, well-differentiated thyroid carcinoma (WDTC) are derived from single-institution clinical cohorts, reports of extensive personal experience, and extrapolation of several common therapeutic practices for this tumor in adults. Because pediatric WDTC is an uncommon malignancy, the issues of its optimal initial and subsequent long-term treatment and follow-up remain controversial. Pediatric patients with WDTC can be divided into two groups: children younger than 10 years of age and teenagers/adolescents between 10 and 18 years of age because these groups have different recurrence and mortality rates. We hereby present our views and interpret them in the light of the pertinent literature. Our recommendations on treatment strategies are more relevant for younger children. After midpuberty, optimal treatment is adequately addressed in the relevant literature on adults. For the majority of patients, total/near-total thyroidectomy is currently recommended as the standard initial therapy for WDTC. This is commonly followed by administration of radioiodine (RAI; (131)I) therapy to destroy residual normal thyroid tissue (remnant). Routine (131)I remnant ablation has been shown to: (1). decrease the risk of local recurrences, (2) increase the sensitivity of subsequent diagnostic RAI whole-body scanning (WBS), and (3) render serum thyroglobulin (Tg) a highly sensitive marker for recurrent/residual disease during long-term follow-up. We recognize that the above practices are not universally adhered to in children and adolescents, because the risk stratification and intensity of applied therapeutic measures are influenced by institutional traditions and personal experience. In our view, aggressive initial management, followed by evaluations at regular intervals after thyroidectomy and (131)I remnant ablation, in conjunction with long-term thyroid hormone suppressive therapy (THST), result in decreased recurrence rates in pediatric patients with WDTC. Follow-up examinations should include a diagnostic RAI ((131)I or (123)I) WBS and measurement of serum Tg, both performed under conditions of TSH stimulation, as well as neck ultrasonography (US). Our strategy is corroborated by data from retrospective clinical cohort studies. In this malignancy, no evidence of disease (NED) status can be defined as the combination of a negative diagnostic WBS and the presence of undetectable or low serum Tg levels, both tested under TSH stimulation. These findings should be accompanied by the absence of anatomically definable disease by standard imaging modalities, e.g., neck US or chest computed tomography (CT). Although the long-term survival rates are good overall in this disease, selected patients may require further surgery or (131)I therapy for the eradication or clinical control of metastases. Finally, and importantly, because the duration of follow-up is lifelong, the care of children with prior diagnosis of WDTC should be transferred to an adult endocrinologist after they reach adulthood, even if they have achieved NED status by that time.

Lack of impact of radioiodine therapy in tg-positive, diagnostic whole-body scan-negative patients with follicular cell-derived thyroid cancer

Several reports have suggested a benefit from radioactive iodine (RAI) therapy in Tg-positive, whole-body scan-negative patients with follicular cell-derived thyroid cancer, who were said to have high rates of visualization of uptake in metastases after therapeutic doses of RAI. We sought to evaluate the rate of visualization of RAI uptake in these patients and determine the effect of such therapy on tumor progression and Tg levels. We studied 24 consecutive patients who had been treated with high-dose RAI, four of whom had no evidence of metastasis or persistent cancer. Our results showed that four patients had some uptake in posttherapy scans: in the neck, lung, and mediastinal metastases in one patient, in the thyroid remnant in two, and in a possible neck microrecurrence in one. In 13 patients with macrometastases-tumors 1 cm or greater-tumors progressed and serum Tg increased; five have died of thyroid cancer. The disease remained stable in the seven patients with micrometastases. We concluded that in high-risk patients with follicular cell-derived thyroid cancer with high Tg levels and negative diagnostic whole-body scans, only a small number showed meaningful uptake after high doses of RAI. Therefore, widespread use of empiric RAI therapy for such patients who have a large tumor burden should not be encouraged.

Dosimetrically determined doses of radioiodine for the treatment of metastatic thyroid carcinoma

In the absence of definitive studies relating radioiodine dose to outcomes, selection of a dose of radioiodine to treat metastatic thyroid carcinoma is problematic, and several approaches have been used. These include empiric fixed doses and doses used on dosimetric approaches specific for each patient. This paper is a review of the rationale and technique for dosimetrically-determined doses of radioiodine for the treatment of metastatic thyroid carcinoma. This review (1) discusses the alternatives for selection of a dose, (2) discusses the two major approaches for determining radioiodine doses dosimetrically, (3) briefly reviews several modifications of these approaches, (4) reviews the literature regarding the results, (5) discusses the side effects of these different approaches, and (6) concludes with recommendations for patient management and future research. This review does not address use of dosimetrically-determined doses of radioiodine for the initial ablation of thyroid tissue postoperatively.

Avaliação experimental do atordoamento da tireóide em camundongos

OBJETIVO: O atordoamento do tecido tireoidiano após doses diagnósticas de iodo-131 é descrito como causa de baixa captação e resposta insatisfatória a doses terapêuticas subseqüentes. O objetivo do presente trabalho foi desenvolver um modelo experimental do atordoamento tireoidiano pós-actínico. MATERIAIS E MÉTODOS: Um total de 63 camundongos recebeu dose equivalente de 45 Sv na tireóide, mediante irradiação com iodo-123. Esta dose é similar à estimada para os remanescentes tireoidianos após administração de 185 MBq (5 mCi) de iodo-131 para pesquisa de corpo inteiro. As medidas de captação tireoidiana de uma dose traçadora de iodo-131 foram efetuadas em subgrupos de nove animais, 2, 3, 5, 7, 12 e 26 dias após a irradiação. A captação nestes subgrupos foi correlacionada à de um grupo controle de nove animais não irradiados. RESULTADOS: A captação de iodo no grupo controle foi de 9,26%. Não foi observada variação significativa do valor médio de captação no período de tempo estudado. Houve aumento da variância das medidas efetuadas cinco dias após a irradiação, quando quatro dos nove animais apresentaram captação menor que 60% da média do grupo controle. CONCLUSÃO: Não houve queda sistemática da captação nos animais submetidos à dose de 45 Sv, notando-se, entretanto, tendência a maior flutuação na captação cinco dias após a irradiação. Estes achados podem ser decorrentes de diferenças interespécies ou podem indicar que o atordoamento com doses nesta faixa dependa de características individuais ou anormalidades funcionais prévias, que se somam ao efeito da radiação.

Renal metastases from thyroid papillary carcinoma: study of sodium iodide symporter expression

Kidney metastases from thyroid cancer are rare. We report two such patients and demonstrate that the in vivo 131I uptake by the kidney metastasis is associated with high levels of sodium iodide (Na+/I-) symporter (NIS) expression in the first case. Case 1: A 61-year-old woman with papillary thyroid carcinoma-follicular variant (PTC-FV) presented with scapular metastasis. After thyroidectomy and scapulectomy, a 131I posttherapy scan showed left upper quadrant uptake. A 3.0-cm metastatic PTC-FV deposit was removed by partial nephrectomy. Case 2: A 53-year-old woman presented with back pain. A computed tomography (CT) scan showed a 3.5-cm renal mass, a multinodular goiter, and lung metastases thought secondary to a renal cell carcinoma. A unilateral nephrectomy revealed metastatic PTC-FV. After thyroidectomy, a 131I posttherapy scan showed lung and skeletal metastases. NIS immunoreactivity in tumoral tissue was strongly positive in the primary tumor, shoulder, and kidney metastasis in case 1, as well as in the primary tumor in case 2. Spotty, low-level NIS expression was observed in the kidney metastasis in case 2. In conclusion, kidney metastases of PTC-FV may occasionally retain adequate levels of NIS expression, enabling their detection during life. Thus, intense uptake in the abdomen during 131I imaging should not be assumed to be physiological gastrointestinal tract residual radionuclide activity.

Evaluation of the patient with a suspected thyroid disorder

The principal types of thyroid disorders described herein can be recognized and evaluated clinically and biochemically by the obstetrician/gynecologist. Most patients with diffuse goiter should be referred for further evaluation and an RAI scan arranged while this consultation is awaited. Patients with solitary thyroid nodules should be referred for FNAB. Primary hypothyroidism without significant goiter can be treated without specialist referral, except in patients at high risk for ischemic coronary disease or arrhythmia. Primary hyperthyroidism, apart from subacute and postpartum thyroiditis, should be referred for specialist evaluation and definitive therapy. An RAI scan and uptake should be ordered, and beta-blocker therapy can be initiated as interim therapy in symptomatic patients. Patients with secondary (i.e., hypothalamic- or pituitary-based) thyroid dysfunction should always be referred for evaluation and treatment of the primary intracranial cause. There are several causes of abnormal thyroid function tests in apparently euthyroid patients, and the clinical context often provides important evidence of their nature. Clinical judgment is an important factor in knowing when to arrange specialist consultation.

Value of protein-bound radioactive iodine measurements in the management of differentiated thyroid cancer treated with (131)I

Measurement of the protein-bound radioactive iodine level (PBI(131)) in the plasma of patients following (131)I-iodide administration for thyroid cancer has been re-examined in a retrospective study of 171 patient episodes. It is shown that whereas the previously used threshold value for the measurement at 6 days does not correlate well with the 3-day whole body scan, there is good agreement between the scan and the temporal changes in PBI(131) from 1-6 days: an increasing PBI(131) correlates with a positive scan, and a decreasing PBI(131) with a negative scan. The area under the curve (AUC) for the PBI(131)-time curve is related to the absorbed dose for the tumour. For a small group of 11 patients, dosimetry estimates were made from serial scans, quantified with phantoms; these absorbed doses correlated with the AUC and the 6-day PBI(131). Therefore, it is suggested that these parameters may be useful in predicting absorbed radiation dose in these patients.

Failure of TSH rise prior to radio-iodine therapy for thyroid cancer: implications for treatment

We describe three patients with well-differentiated thyroid carcinoma in whom no rise in serum thyroid-stimulating hormone (TSH) was observed after the discontinuation of thyroid hormone. In one patient, TSH deficiency was due to panhypopituitarism secondary to the empty sella syndrome. This patient initially failed to respond to (131)I but was subsequently given purified porcine TSH prior to further (131)I therapy. This resulted in a significant fall in the thyroglobulin level. In two further patients, TSH levels were suppressed by functioning follicular thyroid cancer. There was an unexpectedly good (131)I uptake by metastases and they responded clinically. The failure of TSH levels to rise after thyroid hormone withdrawal should prompt investigation of the pituitary-thyroid axis. In patients with hypopituitarism, exogenous TSH is recommended, to increase the (131)I uptake. In contrast, when TSH is suppressed by functioning tumour, radio-iodine treatment may still be effective.

[Diagnostic performance of serum thyroglobin and iodide-131 Na scan according to the type of recurrence in differentiated thyroid carcinoma]

BACKGROUND

There is no consensus about the best follow-up protocol in differentiated thyroid carcinoma (DTC). The aim of this study is to evaluate the usefulness and prognostic value of serum thyroglobulin (Tg) and the iodide-131 whole body scan (WBS) in DTC recurrences as a whole and according to the type of recurrence (local recurrence or distant metastases).

PATIENTS AND METHODS

Thirty-four patients with recurrent DTC recruited in our institution over 15 years, with a minimum 5 years of follow-up and without either distant metastases at time of diagnosis nor detectable anti-Tg antibodies were included in the study. All patients were submitted to total or near-total thyroidectomy and 131INa ablation of postsurgical thyroid remnants. The follow-up included Tg measurement and WBS performed in hypothyroid state.

RESULTS

Serum Tg was increased in the 67.4% of the patients and the WBS was positive in the 82.3%. In the isolated local recurrences the sensitivity of WBS was higher than Tg measurement (93.7 vs 43.7%; p < 0.05), but patients with positive Tg had a worse prognostic. By contrast, in patients with distant metastases the sensitivity of Tg was higher than WBS (83.3 vs 58.3%; p = NS). In 14 patients (41.2%) the results of WBS and Tg were in disagreement. In these cases a worse prognosis was observed when Tg was positive and WBS negative.

CONCLUSIONS

The sensitivity of Tg and WBS is different depending on the type of recurrence. Therefore, both tests complement each other and it is not recommended to omit one of them in the follow-up of DTC.

Treating the patient with differentiated thyroid cancer with thyroglobulin-positive iodine-131 diagnostic scan-negative metastases: including comments on the role of serum thyroglobulin monitoring in tumor surveillance

Differentiated thyroid cancer (DTC) patients, especially the 10% to 15% at high risk of cancer-related death, should have long-term monitoring for detection of recurrence or metastasis. Conventional radiologic and ultrasonographic imaging is useful for localization of recurrent or persistent disease. For patients who have had ablation of residual thyroid tissue, measurement of serum thyroglobulin (Tg) levels and radioactive iodine (RAI) imaging provide highly sensitive tools for early detection. Serum Tg is reliable only in the absence of Tg autoantibodies. Sensitivity increases with TSH stimulation, either by withdrawal of thyroxine (T4) therapy, or administration of recombinant TSH (rTSH). In some patients, serum Tg levels are positive but the RAI whole body scan (WBS) is negative. In these patients, either the recurrent tumor is too small and below the sensitivity of the diagnostic scan, or there is a dissociation between Tg synthesis and the iodine-trapping mechanism. Recent literature suggests that empiric high-dose RAI therapy of Tg-positive diagnostic scan-negative patients may result in a high rate of visualization of uptake in posttherapy scans (PTS). Evidence for subsequent improvement of parameters of disease activity has also been presented. Almost all such reported cases had micrometastases that were not visualized by conventional imaging. In our experience, aggressive macrometastases with negative diagnostic WBS do not show significant uptake after therapeutic doses of RAI. The small size of micrometastases in the first group of patients and a possible defect of the iodine-trapping mechanism in the second group may explain this apparent discrepancy. Based on presently available information, a generalized recommendation for RAI therapy of Tg-positive, diagnostic scan-negative patients should await further studies. Meanwhile, in some high-risk patients, in the absence of alternative therapies, empiric RAI therapy is justified.