Radioactive iodine and the salivary glands

Radioiodine therapy in benign thyroid diseases: effects, side effects, and factors affecting therapeutic outcome

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

Micro-single-photon emission computed tomography image acquisition and quantification of sodium-iodide symporter-mediated radionuclide accumulation in mouse thyroid and salivary glands

BACKGROUND

Micro-single-photon emission computed tomography (SPECT) provides a noninvasive way to evaluate the effects of genetic and/or pharmacological modulation on sodium-iodide symporter (NIS)-mediated radionuclide accumulation in mouse thyroid and salivary glands. However, parameters affecting image acquisition and analysis of mouse thyroids and salivary glands have not been thoroughly investigated. In this study, we investigated the effects of region-of-interest (ROI) selection, collimation, scan time, and imaging orbit on image acquisition and quantification of thyroidal and salivary radionuclide accumulation in mice.

METHODS

The effects of data window minima and maxima on thyroidal and salivary ROI selection using a visual boundary method were examined in SPECT images acquired from mice injected with (123)I NaI. The effects of collimation, scan time, and imaging orbit on counting linearity and signal intensity were investigated using phantoms filled with various activities of (123)I NaI or Tc-99m pertechnetate. Spatial resolution of target organs in whole-animal images was compared between circular orbit with parallel-hole collimation and spiral orbit with five-pinhole collimation. Lastly, the inter-experimental variability of the same mouse scanned multiple times was compared with the intra-experimental variability among different mice scanned at the same time.

RESULTS

Thyroid ROI was separated from salivary glands by empirically increasing the data window maxima. Counting linearity within the range of 0.5-14.2 μCi was validated by phantom imaging using single- or multiple-pinhole collimators with circular or spiral imaging orbit. Scanning time could be shortened to 15 minutes per mouse without compromising counting linearity despite proportionally decreased signal intensity. Whole-animal imaging using a spiral orbit with five-pinhole collimators achieved a high spatial resolution and counting linearity. Finally, the extent of inter-experimental variability of NIS-mediated radionuclide accumulation in the thyroid and salivary glands by SPECT imaging in the same mouse was less than the magnitude of variability among the littermates.

CONCLUSIONS

The impacts of multiple variables and experimental designs on micro-SPECT imaging and quantification of radionuclide accumulation in mouse thyroid and salivary glands can be minimized. This platform will serve as an invaluable tool to screen for pharmacologic reagents that differentially modulate thyroidal and salivary radioiodine accumulation in preclinical mouse models.

Effect of parotid gland massage on parotid gland Tc-99m pertechnetate uptake

BACKGROUND

Salivary dysfunction is the most common side effect associated with (131)I therapy in patients with differentiated thyroid cancer. The purpose of this study was to evaluate the effect of parotid gland (PG) massage on radioisotope accumulation in the salivary gland.

METHODS

Sixty patients were included in this study. Using Tc-99m pertechnetate, two salivary scans were performed in all patients. In 30 patients, PG massage was performed between the two salivary gland scans, whereas in the other 30 patients no massage was performed between the two scans. Total counts of both PGs and accumulation ratios were calculated.

RESULTS

In the patients who received massage, no difference was observed between the mean PG counts of first and second images (8556.9±3333.4 count vs. 8598.3±3341.3 count, p=0.39). In the patients who did not receive massage, the mean PG count on second images was significantly higher than that on first images (8581.2±3618.0 count vs. 9096.4±3654.0 count, p<0.01). Mean accumulation ratio in the patients who received massage was significantly lower than in the patients who did not receive massage (0.5%±3.3% vs. 6.8%±3.8%, p<0.01). Further, among the patients who received massage there was a higher percentage of patients with a negative accumulation ratio than among the patients who did not receive massage (43.3% vs. 0%, p<0.01).

CONCLUSIONS

PG massage can reduce Tc-99m pertechnetate accumulation in the PG, and thus, should be helpful to prevent salivary damage associated with (131)I therapy.

Strategies of radioiodine ablation in patients with low-risk thyroid cancer

BACKGROUND

It is not clear whether the administration of radioiodine provides any benefit to patients with low-risk thyroid cancer after a complete surgical resection. The administration of the smallest possible amount of radioiodine would improve care.

METHODS

In our randomized, phase 3 trial, we compared two thyrotropin-stimulation methods (thyroid hormone withdrawal and use of recombinant human thyrotropin) and two radioiodine ((131)I) doses (i.e., administered activities) (1.1 GBq and 3.7 GBq) in a 2-by-2 design. Inclusion criteria were an age of 18 years or older; total thyroidectomy for differentiated thyroid carcinoma; tumor-node-metastasis (TNM) stage, ascertained on pathological examination (p) of a surgical specimen, of pT1 (with tumor diameter ≤1 cm) and N1 or Nx, pT1 (with tumor diameter >1 to 2 cm) and any N stage, or pT2N0; absence of distant metastasis; and no iodine contamination. Thyroid ablation was assessed 8 months after radioiodine administration by neck ultrasonography and measurement of recombinant human thyrotropin-stimulated thyroglobulin. Comparisons were based on an equivalence framework.

RESULTS

There were 752 patients enrolled between 2007 and 2010; 92% had papillary cancer. There were no unexpected serious adverse events. In the 684 patients with data that could be evaluated, ultrasonography of the neck was normal in 652 (95%), and the stimulated thyroglobulin level was 1.0 ng per milliliter or less in 621 of the 652 patients (95%) without detectable thyroglobulin antibodies. Thyroid ablation was complete in 631 of the 684 patients (92%). The ablation rate was equivalent between the (131)I doses and between the thyrotropin-stimulation methods.

CONCLUSIONS

The use of recombinant human thyrotropin and low-dose (1.1 GBq) postoperative radioiodine ablation may be sufficient for the management of low-risk thyroid cancer. (Funded by the French National Cancer Institute [INCa] and the French Ministry of Health; ClinicalTrials.gov number, NCT00435851; INCa number, RECF0447.).

Assessment of salivary gland dysfunction after radioiodine therapy for thyroid carcinoma using non-contrast-enhanced CT: the significance of changes in volume and attenuation of the glands

BACKGROUND AND PURPOSE

Although radiation induced damage to the salivary gland is a known complication of radioactive iodine ((131)I) therapy for thyroid carcinoma, prediction of the severity and reversibility of sialoadenitis is difficult. Our aim was to correlate the extent of salivary dysfunction assessed by salivary gland scintigraphy with changes in the volume and attenuation of salivary glands on nonenhanced CT in postoperative patients with thyroid cancer treated with RIT.

MATERIALS AND METHODS

Forty patients with thyroid carcinoma, 13 men (age range, 21-80 years) and 27 women (age range, 28-75 years) who underwent a total thyroidectomy and were treated with RIT were assessed retrospectively. On CT, the percentage of volume reduction and the difference in attenuation of the parotid and submandibular glands after RIT were determined and correlated with the extent of radiation-induced salivary dysfunction on scintigraphy.

RESULTS

The salivary gland volume significantly decreased with an increase in the dysfunction grade on scintigraphy for both the parotid and submandibular glands (P < .001). The attenuation significantly increased with an increase in the dysfunction grade on scintigraphy for the parotid gland (P < .001), but not for the submandibular gland. The cutoff value of volume reduction to diagnose severe gland dysfunction was 19.5% (sensitivity, 86.0%; specificity, 100%) for the parotid gland and 31.0% (sensitivity, 100%; specificity, 97.0%) for the submandibular gland, and that of the attenuation change was 9.8 HU (sensitivity, 81.0%; specificity, 95%) for the parotid gland.

CONCLUSIONS

The reduction in volume of the parotid and submandibular glands and the increase in attenuation of the parotid gland on nonenhanced CT can be indicators of the grade of RIT-induced salivary dysfunction.

Long-term outcomes of distant metastasis from differentiated thyroid carcinoma

BACKGROUND

  The aim of this study was to identify the prognostic factors of long-term survival and optimal therapeutic protocol for patients with distant metastasis secondary to differentiated thyroid carcinoma (DTC).

METHODS

  A retrospective review of 1665 patients with DTC treated at a regional tertiary hospital in Taiwan between 1986 and 2010 was performed. Among them, 207 patients were found to have distant metastasis. For a long-term outcome survey, 126 patients that had received at least 5 years (mean 9·6 ± 5·2 years) of follow-up after the diagnosis of distant metastasis were analysed for this study. Prognostic factor analysis included age, sex, histology, disease stage, type of surgical procedure, site of metastatic foci, (131) I avidity of tumour, thyroglobulin (Tg) level and accumulated therapeutic dose of radioiodine (RAI).

RESULTS

  The mean age at diagnosis of distant metastasis was 46·4 ± 17·2 years. The female-to-male ratio was 2·1:1. The 10- and 15-year survival rates were 70·6% and 64·9%, respectively. The independent predictors of survival were younger age, surgical dissection of neck lymph nodes (LNs) and low TSH-stimulated Tg level (<400 μg/l) at the discovery of metastasis. Most cases of resolved (131) I-avid disease (79·2%) and disease-free remission (87·5%) received a cumulative dose no >600 mCi of (131) I. The mean cumulative doses of (131) I in both deceased and living patients were similar.

CONCLUSION

  The prognosis of patients with distant metastasis from DTC within this study was found to be favourable. Survival may be improved by surgical dissection of neck LNs, but repeated (131) I therapy >600 mCi is not advised unless there is a high probability that it would benefit the patient.

Changes in TNM stage, reoperation and 131-I ablation rate during the use of newer methods for the preoperative diagnosis of differentiated thyroid carcinoma

OBJECTIVE

To define and discuss the changes of important risk factors and TNM staging over the last 40 years in patients operated on for differentiated thyroid carcinoma (DTC), resulting from the introduction of newer sensitive diagnostic procedures in the preoperative evaluation of thyroid nodules.

PATIENTS

We reviewed the medical records of 1251 patients with postoperative diagnosis of DTC who had undergone initial diagnosis, before surgery, at our unit, between 1971 and 2010. According to the period of diagnosis, the patients were divided into four groups (I, II, III, IV) corresponding to the four decades.

RESULTS

The mean age at diagnosis was unchanged over time for both papillary (PTC) and follicular thyroid cancer (FTC). A decrease in the proportion of FTC (group I vs group IV P < 0·01) and a concomitant increase in PTC/FTC ratio was observed particularly in group IV. The significant decrease in the proportion of tumour size of PTC (group I vs group IV, P < 0·01), the increase in the proportion of microcarcinomas, from 22·4% in group I to 53·0% in group IV, P < 0·001, and the decrease in the number of cases with features of aggressiveness have changed the TNM stage towards stages I and II. The overall frequency of patients at high risk was significantly decreased, from 8·0% in group I to 1·8% in group IV. The number of patients who underwent reoperation for the completion of tumour resection and/or radioiodine therapy significantly decreased over time.

CONCLUSIONS

The evaluation of thyroid nodules using the newer diagnostic methods was useful in identifying DTC early. Consequently, the reoperation and thyroid remnant ablation rates were reduced.

Taste evaluation in adolescents and pediatric patients with benign migratory glossitis

OBJECTIVE

Benign migratory glossitis (BMG) is a disease that affects the tongue and is considered an inflammatory disorder well recognized. It is characterized by the appearance of erosive areas on the dorsum and lateral border of the tongue that can be isolated or multiple. The aim of this study was to assess whether the perception of taste to the four basic tastes is altered due to the presence of BMG.

METHODS

Forty individuals of both sexes with a mean age of 12.1 years were divided into two groups (20 BMG patients and 20 healthy controls) and had their taste function assessed in relation to four basic tastes: bitter, sour, sweet, and salty.

RESULTS

All participants in the case group exhibited lesions over the dorsum, edges and tip of the tongue with a possible extension to the surface below. No statistic difference was observed between BMG patients and controls for the taste scores (Mann-Whitney U test: P=0.0955). The percentage of correctly identified taste strips for the highest concentrations was 100% for all tastes. For the lowest concentrations it was 85% for sweet, 50% for sour, 95% for salty, and 95% for bitter. Three patients with BMG and three control subjects showed hypogeusia.

CONCLUSION

This study revealed that BMG is not able to change the perception of taste for salty, sweet, sour and bitter.

Rising incidence of second cancers in patients with low-risk (T1N0) thyroid cancer who receive radioactive iodine therapy

BACKGROUND

American Thyroid Association guidelines currently recommend the selective use of radioactive iodine (RAI) therapy in patients with well differentiated thyroid cancer (WDTC). Despite these guidelines, RAI ablation has been used routinely in all but the very lowest risk patients with thyroid cancer over the last 30 years. The objective of this study was to evaluate patterns of RAI use and elevated risk of secondary primary malignancies (SPM) in patients with low-risk (T1N0) WDTC.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was used to analyze trends in RAI use over time in the United States. To determine the excess risk of SPM, the standardized incidence ratio (SIR) and excess absolute risk (EAR) of various cancers were calculated in the 2 cohorts. Between 1973 and 2007, 37,176 patients with WDTC were followed in the SEER Program, equating to 408,750 person-years at risk (PYR). In total, 14,589 patients received RAI, and SPMs were observed in 3223 patients.

RESULTS

During the study period, the rate of RAI use in patients with low-risk (T1N0) WDTC increased from 3.3% to 38.1%. For low-risk patients, the SIR of SPM was 1.21 (95% confidence interval [CI], 0.93-1.54), and the EAR was 4.6 excess cases per 10,000 PYR. SPM with significantly elevated risk because of RAI were salivary gland malignancies (SIR = 11.13; 95% CI, 1.35-40.2) and leukemia (SIR = 5.68; 95% CI, 2.09-12.37). The excess risk of leukemia was significantly greater in patients aged <45 years (SIR = 5.32; 95% CI, 2.75-9.30) compared with the excess risk in older patients (SIR = 2.26; 95% CI, 1.43-3.39).

CONCLUSIONS

The increased risk of a SPM in patients with low-risk (T1N0) WDTC, along with a lack of data demonstrating improved survival outcomes with adjuvant RAI, provide a compelling argument in favor of rationing the use of RAI in this patient population.

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.

Salivary gland disorders

Salivary gland abnormalities and salivary dysfunction are important orofacial disorders. Patients with such problems are usually seen in the dental office for evaluation and therapy, and the dental practitioner is required to make a diagnosis and institute care. Therefore, it is necessary for the dentist to be knowledgeable regarding the more common pathologic entities that involve the salivary apparatus, and also be familiar with the diagnostic and therapeutic tools that are available. Successful diagnosis is dependent on the organized integration of the information derived from past history, clinical examination, salivary volume study, imaging, serology, and histopathologic examination. This article discusses the most common disorders seen in the Salivary Gland Center and indicates the current approaches to diagnosis. Improvement in diagnostic skills will avoid serious complications and lead to specific and effective therapy.

Radiopharmacokinetics of radioiodine in the parotid glands after the administration of lemon juice

BACKGROUND

The ability of sialagogues to increase or decrease radiation induced-sialoadenitis and/or xerostomia after therapeutic administration of ¹³¹I is controversial. To evaluate this we measured the radiopharmacokinetics of ¹²³I in the parotid glands (PGs) after its administration of lemon juice (LJ).

METHODS

A retrospective review was performed on all patients who had a salivary gland scan performed before ¹³¹I therapy between July 2008 and April 2009 at the Washington Hospital Center. Two hours after ¹²³I was given orally, dynamic scintigraphy was initiated. Five milliliters of LJ was given 5 minutes later. Then, the patient was imaged for 1 hour (phase 1) at which point the sequence was repeated (phase 2). Twenty-three patients were studied. For each PG, the presence or absence of uptake was assessed, and based on background corrected counts, the mean, range, and standard deviation were determined for multiple radiopharmacokinetic parameters such as (i) percent radioiodine washout, (ii) time from LJ administration to re-accumulation of radioiodine to pre-LJ activity, and (iii) percent reduction in radiation absorbed dose to the PGs if LJ had been re-administered at the time the radioiodine activity re-accumulated to the pre-LJ activity.

RESULTS

The mean  ± one standard deviation and range for percent washout were 84%  ± 18% (35%-100%) and 83%  ±  21% (37%-100%) in phase 1 and 2, respectively. The times from LJ to re-accumulation of the radioiodine to the pre-LJ activity were 21  ± 10 minutes (4-45 minutes) and 40  ± 14 minutes (12-62 minutes) for phase 1 and 2, respectively. The estimated percent reduction in radiation absorbed dose to the PGs following the first and second administration of LJ was 37%  ± 14% (13%-93%) and 47% ± 16% (21%-97%), respectively.

CONCLUSIONS

The washout of radioiodine from the PGs is rapid but transient. Early repeat administration may result in continued and cumulative reduction of radiation absorbed dose in the PGs.

Inhibition of uPAR and uPA reduces invasion in papillary thyroid carcinoma cells

OBJECTIVES/HYPOTHESIS

We analyzed the expression of urokinase plasminogen activator (uPA) and its receptor (uPAR) in papillary thyroid carcinoma (PTC) and normal thyroid tissue and examined in vitro how uPA and uPAR contribute to an invasive/metastatic phenotype, and the functional consequences of inhibiting this system.

STUDY DESIGN

Retrospective chart review of PTC patients, followed by prospective study using previously obtained patient tissue and PTC cellular models.

METHODS

uPA and uPAR RNA and protein levels were analyzed in PTC patient tissue samples, PTC and normal thyroid tissue culture cells, and conditioned media (CM) using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and/or Western blotting. The plasminogen-activating ability of CM was examined using dark-quenched casein fluorimetry and casein-plasminogen gel zymography. The invasive potentials of the PTC and normal thyroid epithelial cell lines were assessed using an in vitro cellular invasion/migration system.

RESULTS

uPA and uPAR RNA and protein levels were increased in PTC patient samples and PTC cells relative to controls. uPA and uPAR RNA were also significantly higher in patients with metastatic disease. Casein-plasminogen zymography and Western blotting demonstrated increased active uPA secreted by PTC cells compared with normal thyroid cells. Fluorimetric assays revealed that the PTC cells' CM was able to activate plasminogen, resulting in measurable casein hydrolysis. This casein hydrolysis was prevented by the addition of several specific uPA inhibitors. Finally, the in vitro invasion phenotypes of PTC cells were augmented by the addition of plasminogen, and this augmentation was reversed by inhibitory anti-uPA and anti-uPAR antibodies.

CONCLUSIONS

These data provide new functional evidence of the uPA/uPAR system's role in PTC invasion/metastasis and demonstrate the attractiveness of uPA and uPAR as molecular biomarkers and therapeutic targets.

Salivary gland malignancy and radioiodine therapy for thyroid cancer

BACKGROUND

The risk of second primary malignancies in patients with well-differentiated thyroid cancer is of special interest because of the common use of radioactive iodine (RAI) ablation and/or treatment of these patients and the theoretical risk of subsequent nonthyroid malignancies associated with the radiation exposure. This brief report focuses specifically on the occurrence of second primary malignancies of the salivary glands. RAI residency within salivary tissues is known to have both acute and chronic consequences on salivary function, but secondary neoplasia is quite unusual.

SUMMARY

We present a very rare case of a patient with papillary thyroid cancer treated with 600 mCi of RAI, who subsequently developed salivary gland cancer.

CONCLUSIONS

We recommend salivary gland protection to diminish potential side effects after the exposure to radioiodine. On the basis of our experience we suggest administration of sialogogues (such as lemon juice) continuously, every 30-60 minutes for 24 hours, after RAI administration.

Neonatal hyperthyroidism associated with isolated submandibular sialadenitis: is it just a coincidence?

Isolated submandibular sialadenitis is extremely rare in the neonatal period. All reported cases had predisposing factors such as prematurity, dehydration, anatomic deformities, calculi, and long-term oro-gastric tube feeding. Here, we present a case of neonatal isolated submandibular sialadenitis without any known risk factors and who was diagnosed later with hyperthyroidism secondary to maternal Graves' disease. Both sialadenitis and hyperthyroidism resolved with appropriate treatment. While both conditions are rare and important in neonatal emergency care, the possibility of neonatal hyperthyroidism should be explored in cases with isolated sialadenitis if there is no other risk factor. Possible mechanisms for this uncommon association are discussed.

Does amifostine have radioprotective effects on salivary glands in high-dose radioactive iodine-treated differentiated thyroid cancer

OBJECTIVES

To assess the effects of amifostine on salivary glands in radioactive iodine-treated differentiated thyroid cancer.

METHODS

We searched the MEDLINE, EMBASE and the Cochrane Library for randomized controlled clinical trials which compared the effects of amifostine with those of placebo or acid-stimulating agents.

RESULTS

Two randomized controlled clinical trials with a total of 130 patients were included. Both studies had a low risk of bias. There were no statistically significant differences between the effects of amifostine and acid-stimulating agents on the incidence of xerostomia (RR 0.24, 95% CI 0.01 to 9.52), the decrease of scintigraphically measured uptake of (99m)Tc by the parotid (RR 0.30, 95% CI -2.28 to 2.88) or submandibular glands (RR 1.90, 95% CI -1.46 to 5.26) at 12 months, or the reduction in blood pressure (RR 5.00, 95% CI 0.25 to 99.16). Neither of the included trials investigated death from any cause, morbidity, health-related quality of life or costs.

CONCLUSION

The results of two randomized controlled clinical trials suggest that amifostine has no significant radioprotective effects on salivary glands in radioactive iodine treatment of differentiated thyroid cancer. The use of acid-stimulating agents to increase salivation should remain the first choice during radioactive iodine treatment of differentiated thyroid cancer. Patients should also be well informed of the importance of hydration and acid stimulation.

Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the publication of the American Thyroid Association's guidelines for the management of these disorders was published in 2006, a large amount of new information has become available, prompting a revision of the guidelines.

METHODS

Relevant articles through December 2008 were reviewed by the task force and categorized by topic and level of evidence according to a modified schema used by the United States Preventative Services Task Force.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to optimal surgical management, radioiodine remnant ablation, and suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using ultrasound and serum thyroglobulin as well as those related to management of recurrent and metastatic disease.

CONCLUSIONS

We created evidence-based recommendations in response to our appointment as an independent task force by the American Thyroid Association to assist in the clinical management of patients with thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Amifostine for salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer

BACKGROUND

Radioactive iodine treatment for differentiated thyroid cancer possibly results in xerostomia. Amifostine has been used to prevent the effects of irradiation to salivary glands. To date, the effects of amifostine on salivary glands in radioactive iodine treated differentiated thyroid cancer remain uncertain.

OBJECTIVES

To assess the effects of amifostine on salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer.

SEARCH STRATEGY

Studies were obtained from computerized searches of MEDLINE, EMBASE, The Cochrane Library and paper collections of conferences held in Chinese.

SELECTION CRITERIA

Randomised controlled clinical trials and quasi-randomised controlled clinical trials comparing the effects of amifostine on salivary glands after radioactive iodine treatment for differentiated thyroid cancer with placebo and a duration of follow up of at least three months.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data.

MAIN RESULTS

Two trials with 130 patients (67 and 63 patients randomised to intervention versus control) were included. Both studies had a low risk of bias. Amifostine versus placebo showed no statistically significant differences in the incidence of xerostomia (130 patients, two studies), the decrease of scintigraphically measured uptake of technetium-99m by salivary or submandibular glands at twelve months (80 patients, one study), and the reduction of blood pressure (130 patients, two studies). Two patients in one study collapsed after initiation of amifostine therapy and had to be treated by withdrawing the infusion and volume substitution. Both patients recovered without sequelae. Meta-analysis was not performed on the function of salivary glands measured by technetium-99m scintigraphy at three months after high dose radioactive iodine treatment due to the highly inconsistent findings across studies (I(2) statistic 99%). None of the included trials investigated death from any cause, morbidity, health-related quality of life or costs.

AUTHORS' CONCLUSIONS

Results from two randomised controlled clinical trials suggest that the amifostine has no significant radioprotective effects on salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer patients. Moreover, no health-related quality of life and other patient-oriented outcomes were evaluated in the two included trials. Randomised controlled clinical trials with low risk of bias investigating patient-oriented outcomes are needed to guide treatment choice.

Mild decreases in white blood cell and platelet counts are present one year after radioactive iodine remnant ablation

BACKGROUND

Bone marrow suppression after multiple, high-dose radioactive iodine (RAI) therapies is well described. However, changes in the peripheral complete blood count (CBC) that may occur after a single treatment of RAI such as that commonly used for routine remnant ablation is much less well studied. In this retrospective trial, we examined the rate of persistent anemia, leukopenia, and thrombocytopenia 1 year after a single RAI administration.

METHODS

Peripheral blood counts at baseline were compared to those obtained 1 year after RAI remnant ablation in 206 consecutive thyroid cancer patients. Analyses were performed to determine the potential impact of both the method of preparation (recombinant human thyroid stimulating hormone [rhTSH] vs. thyroid hormone withdrawal) and administered activity of (131)I on hemoglobin, white blood cell (WBC), and platelet counts.

RESULTS

Comparison of the baseline CBC before RAI ablation (median administered activity of approximately 3700 MBq or 100 mCi) with the follow-up CBC done 1 year later demonstrated a statistically significant decline in total WBC (6.7 +/- 2.1 x 10(9) vs. 6.0 +/- 1.8 x 10(9)/L, p < 0.001; 9.7% below the reference range at 1-year follow-up) and platelet (272 +/- 67 vs. 250 +/- 65 x 10(9)/L, p < 0.001; 5.8% below the reference range at 1-year follow-up) with no significant change in hemoglobin (1.40 +/- 0.14 vs. 1.40 +/- 0.14 g/L or 14.0 +/- 1.4 vs. 14.0 +/- 1.4 g/dL; 1.5% below the reference range at 1-year follow-up). There were no significant clinical complications observed during the 1-year follow-up period. The changes in total WBC and platelets were not related to the method of preparation or the administered activity of RAI.

CONCLUSION

A single RAI treatment of approximately 3700 MBq (100 mCi) after thyroidectomy is associated with a statistically significant, mild decline in WBC and platelet counts that persists for at least 1 year after ablation. Given the small magnitude of the changes and the lack of clinically significant adverse events, these observations should not decrease the use of RAI ablation in moderate to high-risk patients in whom the benefits of ablation are likely to outweigh these minor risks.

On approaches to the functional restoration of salivary glands damaged by radiation therapy for head and neck cancer, with a review of related aspects of salivary gland morphology and development

Radiation therapy for cancer of the head and neck can devastate the salivary glands and partially devitalize the mandible and maxilla. As a result, saliva production is drastically reduced and its quality adversely altered. Without diligent home and professional care, the teeth are subject to rapid destruction by caries, necessitating extractions with attendant high risk of necrosis of the supporting bone. Innovative techniques in delivery of radiation therapy and administration of drugs that selectively protect normal tissues can reduce significantly the radiation effects on salivary glands. Nonetheless, many patients still suffer severe oral dryness. I review here the functional morphology and development of salivary glands as these relate to approaches to preventing and restoring radiation-induced loss of salivary function. The acinar cells are responsible for most of the fluid and organic material in saliva, while the larger ducts influence the inorganic content. A central theme of this review is the extent to which the several types of epithelial cells in salivary glands may be pluripotential and the circumstances that may influence their ability to replace cells that have been lost or functionally inactivated due to the effects of radiation. The evidence suggests that the highly differentiated cells of the acini and large ducts of mature glands can replace themselves except when the respective pools of available cells are greatly diminished via apoptosis or necrosis owing to severely stressful events. Under the latter circumstances, relatively undifferentiated cells in the intercalated ducts proliferate and redifferentiate as may be required to replenish the depleted pools. It is likely that some, if not many, acinar cells may de-differentiate into intercalated duct-like cells and thus add to the pool of progenitor cells in such situations. If the stress is heavy doses of radiation, however, the result is not only the death of acinar cells, but also a marked decline in functional differentiation and proliferative capacity of all of the surviving cells, including those with progenitor capability. Restoration of gland function, therefore, seems to require increasing the secretory capacity of the surviving cells, or replacing the acinar cells and their progenitors either in the existing gland remnants or with artificial glands.

Thyroid cancer in young adults

The incidence of thyroid cancer in young adults is rising. Differentiated carcinoma (ie, papillary, follicular, and their variants) and medullary thyroid carcinoma (MTC) represent the two most common subtypes, with differing etiologies, prognoses, and management strategies. Ultrasound (US)-guided fine needle aspiration (FNA) is the best initial test for evaluating a nodule or mass suspicious for malignancy. Tumor histology, in addition to radiographic findings and clinical presentation, guides surgical management, the need for adjuvant therapies, and the optimal approach to long-term follow-up. Radioactive iodine (RAI) is used to reduce recurrence and improve survival for differentiated thyroid carcinomas (DTCs). Emerging systemic therapies provide options for patients with progressive metastatic MTC or radio-resistant DTC. Overall, the prognosis for the most common thyroid malignancy, papillary thyroid carcinoma (PTC), is excellent. The treatment of young adult thyroid cancer patients occurs optimally as part of a multidisciplinary coordination of care.

Guidelines for radioiodine therapy of differentiated thyroid cancer

INTRODUCTION

The purpose of the present guidelines on the radioiodine therapy (RAIT) of differentiated thyroid cancer (DTC) formulated by the European Association of Nuclear Medicine (EANM) Therapy Committee is to provide advice to nuclear medicine clinicians and other members of the DTC-treating community on how to ablate thyroid remnant or treat inoperable advanced DTC or both employing large 131-iodine ((131)I) activities.

DISCUSSION

For this purpose, recommendations have been formulated based on recent literature and expert opinion regarding the rationale, indications and contraindications for these procedures, as well as the radioiodine activities and the administration and patient preparation techniques to be used. Recommendations also are provided on pre-RAIT history and examinations, patient counselling and precautions that should be associated with (131)I iodine ablation and treatment. Furthermore, potential side effects of radioiodine therapy and alternate or additional treatments to this modality are reviewed. Appendices furnish information on dosimetry and post-therapy scintigraphy.

Recombinant human thyroid stimulating hormone in 2008: focus on thyroid cancer management

Radioiodine (RAI) ablation following thyroidectomy is standard of care treatment for patients with intermediate or high risk differentiated thyroid cancer. Traditionally, this has been achieved by forgoing thyroid hormone replacement postoperatively, allowing endogenous thyroid stimulating hormone (TSH) levels to rise. This rise in TSH provides the stimulus for RAI uptake by the thyroid remnant, but is associated with clinical hypothyroidism and its associated morbidities. Recombinant human TSH (rhTSH, thyrotropin alfa [Thyrogen^®], Genzyme Corporation, Cambridge, MA, USA) was developed to provide TSH stimulation without withdrawal of thyroid hormone and clinical hypothyroidism. Phase III studies reported equivalent detection of recurrent or residual disease when rhTSH was used compared with thyroid hormone withdrawal (THW). These trials led to its approval as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without RAI imaging in the surveillance of patients with differentiated thyroid cancer. Recently, rhTSH was given an indication for adjunctive preparation for thyroid remnant ablation after phase III studies demonstrated comparable outcomes for rhTSH preparation when compared with THW. Importantly, rhTSH stimulation has been found to be safe, well tolerated, and to result in improved quality of life. Here, we review the efficacy and tolerability studies leading to the approval for the use of rhTSH in well-differentiated thyroid cancer management.

Evaluation of the radioprotective effect of turmeric extract and vitamin E in mice exposed to therapeutic dose of radioiodine

The aim of this study was to evaluate the radioprotective effect of turmeric extract (40 mg/kg body weight) and vitamin E (α- tocopherol acetate, 400 IU/kg body weight) supplementation on lipid peroxidation, reduced glutathione and antioxidant defense enzymes in various organs like liver, kidney and salivary glands at 24 h in adult Swiss mice. (131)Iodine exposure significantly increased lipid peroxidation in kidney and salivary glands in comparison to control animals. Pre supplementation with turmeric extract for 15 days showed significant lowering of lipid peroxidation in kidney. On the other hand vitamin E pre supplementation showed marked reduction in lipid peroxidation in salivary glands. Reduced glutathione levels decreased significantly in liver after radiation exposure. However, pre supplementation with turmeric extract and vitamin E did not improve glutathione levels in liver. In conclusion, we have observed differential radioprotective effect of turmeric extract and vitamin E in kidney and salivary glands. However, Vitamin E seems to offer better radioprotection for salivary glands which is known to be the major site of cellular destruction after radioiodine therapy in patients.

The Slc26a4 transporter functions as an electroneutral Cl-/I-/HCO3- exchanger: role of Slc26a4 and Slc26a6 in I- and HCO3- secretion and in regulation of CFTR in the parotid duct

Transcellular Cl(-) and HCO(3)(-) transport is a vital function of secretory epithelia and exit across the luminal membrane is mediated by members of the SLC26 transporters in conjunction with cystic fibrosis transmembrane conductance regulator (CFTR) channel. Typically, secretory epithelia express several SLC26 transporters in the same tissue; however, how their specific function is determined in vivo is not known. In the present work we used the parotid gland duct which expressed Slc26a4 and Slc26a6 and the model systems of Slc26a4(-/-) and Slc26a6(-/-) mice to study the role and regulation of these SLC26 transporters. We examined the transport modes of SLC26A4 expressed in Xenopus oocytes and report that SLC26A4 functions as a coupled, electroneutral I(-)/Cl(-), I(-)/HCO(3)(-) and Cl(-)/HCO(3)(-) exchanger with 1: 1 stoichiometry, with I(-) as the preferred anion. In the duct, Slc26a4 is expressed in the luminal membrane and mainly mediates I(-) secretion with minimal role in luminal HCO(3)(-) transport. By contrast, Slc26a6 mediates luminal Cl(-)/HCO(3)(-) exchange activity with minimal role in I(-) secretion. Furthermore, silencing of CFTR altered Cl(-)/HCO(3)(-) exchange by Slc26a6, but had no effect on I(-) secretion by Slc26a4. Accordingly, deletion of Slc26a6, but not deletion of Slc26a4, results in dysregulation of CFTR. These findings provide the first evidence for a selective role of the SLC26 transporters expressed in the same tissue in epithelial anion transport and suggest that transport specificity is achieved by both the properties of the transporters and the composition of the complexes they form.

131I effective half-life and dosimetry in thyroid cancer patients

(131)I treatment in thyroid cancer patients may induce side effects, including extrathyroidal cancer and leukemia. There are still some uncertainties concerning parameters that may influence the effective half-life of (131)I and the absorbed doses by extrathyroidal organs.

METHODS

Whole-body retention of radioiodine was measured in 254 patients, and repeated quantitative whole-body scans and measurements of the urinary excretion of (131)I were performed on 30 of these patients.

RESULTS

The mean effective half-life (10.5 h) was shorter by 31%, with little difference between patients, in the 36 patients who received recombinant human thyroid-stimulating hormone than in the 218 patients who underwent thyroid hormone withdrawal (15.7 h). The residence times in the stomach and in the rest of the body were significantly shorter in patients who received recombinant human thyroid-stimulating hormone than in patients who underwent withdrawal, but the residence times were similar in the colon and bladder.

CONCLUSION

In patients who undergo thyroid hormone withdrawal, the longer mean effective half-life is mainly due to delayed renal excretion of (131)I and results in dose estimates higher than the data in report 53 of the International Commission on Radiological Protection, which were obtained from healthy, euthyroid subjects.

Transient sialoadenitis: a complication of 131I-metaiodobenzylguanidine therapy

Radioiodinated metaiodobenzylguanidine [(131)I-MIBG] is commonly used to treat resistant neuroblastoma or metastatic pheochromocytoma [MP] with little non-hematopoietic toxicity. We describe here transient sialoadenitis, a previously unreported complication. Ten patients [9 neuroblastoma and 1 MP] received 12-18 mCi/kg of (131)I-MIBG. Five patients had bilateral parotid swelling, two with associated buccal discomfort within 24 hr of injection which subsided within 48 hr. Grade 3 or 4 serum amylase elevation was documented in 8/8 patients tested [median 1,336; range: 576-8,830 U/L] which normalized [25-125 U/L] within 4-14 [median 5.5] days. Serum lipase remained normal. Patients did not develop subsequent dry mouth or dysphagia.

Reducing the incidence of 131I-induced sialadenitis: the role of pilocarpine

The goal of this study was to reduce the salivary symptoms of pain and xerostomia caused by 131I therapy for papillary and follicular thyroid carcinoma.

METHODS

In a single-blind controlled prospective study of 60 patients, we investigated whether pilocarpine, 5 mg orally every 8 h for 1 wk after 131I therapy, would reduce salivary symptoms. All patients received 8 mg of dexamethasone and 100 mg of dolasetron mesylate orally 2 h before therapy and every 12 h for another 5 doses after 131I ingestion. In addition, for a week after therapy all drank 2,400 mL of nondairy liquid per day and had sugar-free gum or candy in their mouths at all times when awake for a week and, for the first 3 nights, every 3 h after retiring. All brushed their mouths out every 3 h while awake and also for the first 3 nights after 131I therapy. Symptoms and signs were followed by frequent telephone calls over the first week and every 8-12 wk thereafter, a physical examination within the first 10 d after therapy, and a clinic visit 6-8 mo after therapy. Statistical comparisons were by chi2 analysis.

RESULTS

The 2 patient groups were not statistically different in age, sex, type of thyroid cancer, or 131I activity administered (P > 0.05). There were no statistical differences between the groups in the prevalence of sialadenitis, stomatitis, xerostomia, or dysgeusia over the next 6 mo (P > 0.05).

CONCLUSION

Under the conditions of the study, pilocarpine did not reduce the occurrence of radiation sialadenitis or stomatitis. The occurrence, however, was lower than had previously been reported in the literature, possibly because of the concurrent stringent application of physiologic sialogogues (candy, gum, fluids), dexamethasone, and dolasetron mesylate, a serotonin receptor antagonist.

Childhood thyroid cancers and radioactive iodine therapy: necessity of precautious radiation health risk management

One of the lessons from Chernobyl's legacy on health impact beyond 20 years is not only how to detect and treat the patients with radiation-associated thyroid cancers but how to follow up those who received radioactive iodine treatment repetitively after surgery in order to monitor any recurrence/worsening and also how to predict the risk of secondary primary cancers for their lifetime period. To evaluate the possibility of second primary tumors after radioactive iodine treatment, we reviewed the reports on risks from both external and internal radiation exposure, especially at high doses during childhood through an internet service of the National Library of Medicine and the National Institutes of Health, PubMed by the end of June, 2007, together with our own experience of Chernobyl childhood thyroid cancers. Children who were internally exposed after Chernobyl accident have a long-term risk of well differentiated thyroid cancers. Once they have disease, ironically radioactive iodine ablation is one of the useful therapies after surgical treatment. Elevated risks of solid cancers and leukemia have been found in radioiodine-treated patients, however, so far precious few reports from Chernobyl thyroid cancer patient were published. To reduce the adverse effects of radioactive iodine therapy on non-target tissues, recombinant human TSH has been applied and proved effective. Period of latency of second primary cancers may be very long. Therefore patients treated with high activities of radioactive iodine, especially children cases, should be carefully followed up during their whole lifespan.