Does vitamin E protect salivary glands from I-131 radiation damage in patients with thyroid cancer?

Effect of vitamin E and supragingival scaling on salivary gland function in patients with differentiated thyroid cancer treated with 131I

OBJECTIVE

The aim of this study was to evaluate the effect of vitamin E and supragingival scaling with vitamin C on the salivary glands of patients with differentiated thyroid carcinoma after 131I treatment.

METHODS

A total of 89 prospective patients with differentiated thyroid carcinoma were enrolled and randomly divided into the following groups: vitamin E group (n = 30, group A), vitamin C group (n = 30, group B) and supragingival scaling with vitamin C group (n = 29, group C). Using functional indices (e.g. maximum uptake fraction, uptake index, excretion fraction, secretion time and excretion rate), changes in the salivary gland functions before and a month after 131I treatment were assessed by dynamic imaging of salivary gland.

RESULTS

We compared the before and after 131I therapy results of the three groups. In group A (P  < 0.05), the excretion fraction and excretion rate of the left parotid gland were significantly higher, and the uptake index of the bilateral submandibular glands was significantly lower. No significant changes in salivary gland functional parameters were observed in group B (P > 0.05). The uptake index of the bilateral parotid glands and the excretion rate of the left parotid gland were significantly higher in group C (P < 0.05). The degree of serum amylase level reduction decreased significantly in group C (P < 0.05).

CONCLUSION

Vitamin E showed a protective effect on parotid excretion function in patients with differentiated thyroid carcinoma who underwent 131I treatment. Supragingival scaling may be a promising radiation protector because it is associated with a protective effect on the salivary gland functions.

Quantitative Scintigraphy Evaluated the Relationship between 131I Therapy and Salivary Glands Function in DTC Patients: A Retrospective Analysis

Purpose

Quantitative scintigraphy to evaluate salivary gland function changes in patients with differentiated thyroid cancer (DTC) after iodine-131 (¹³¹I) treatment.

Methods

A total of 458 patients with DTC grouped by sex and age were included. Salivary gland scintigraphy was performed to evaluate salivary gland function before and after ¹³¹I treatment. The uptake fraction (UF), uptake index (UI), and excretion fraction (EF) of two pairs of parotid glands and submandibular glands were measured and compared. The Chi-square test was conducted according to function impairment count.

Results

Salivary gland function in different age groups and sexes were quite different, especially for women <55 years old, who had decreased UF, UI, and EF of all four glands without basal injury. The secretion or uptake function of some salivary glands with basic function impairment before ¹³¹I treatment was increased after iodine treatment. Only a small percentage of males showed reduced functional parameters after several treatments. The most significant difference in the count of impairment for the four salivary glands were the first and third examinations, which was more evident in women. The submandibular gland had the most significant reduction in uptake.

Conclusion

Changes in salivary gland function are more common in young females being treated for DTC. Impairment of salivary gland function is correlated with the number of treatments and the cumulative dose of ¹³¹I. Some salivary gland functions impaired before ¹³¹I treatment were enhanced in the early treatment.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

SYSTEMATIC REVIEW REGISTRATION

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

The Vitamin E Isoform α-Tocopherol is Not Effective as a Complementary Treatment in Cancer Treatment: A Systematic Review

The term vitamin E describes tocopherols and tocotrienols, whose chemical variations result in different biological activities including antioxidants. Neuroprotective effects of alpha-tocopherol against different toxins are assumed, therefore, it is discussed as a possible protective factor for adverse effects in cancer treatment. In July 2020, a systematic search was conducted searching five databases (Embase, Cochrane, PsychInfo, Cinahl, Medline) to find studies concerning the impact of α-tocopherol application and its potential harm on cancer patients. From 7546 search results, 22 publications referring to 20 studies with 1941 patients were included. Included patients were diagnosed with various cancer types and stages. Outcome variables were overall survival of cancer, symptom management of mucositis and chemotherapy-induced peripheral neuropathy (CIPN). The studies had different methodological qualities (mainly acceptable) and reported heterogeneous results: some reported significant improvement of mucositis and CIPN while others did not find changes concerning these endpoints. Due to heterogeneous results and methodical limitations of the included studies, a clear statement regarding the effectiveness of α-tocopherol as complementary treatment for cancer patients is not possible. Despite findings regarding reduction of oral side effects, usage of α-tocopherol during therapy must be discouraged because of potential negative influence on survival rates.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

A pretest-posttest pilot study for the development and preliminary validation of a tool for the clinical assessment of radioiodine induced sialadenitis

Objectives:

The clinical assessment of radioiodine-induced sialadenitis is relied on the observer-defined toxicity grading model. However, this model has significant limitations, the major one being the lack of systematic assessment based on objective criteria. The main aim of this study was the development and testing of an assessment tool which could examine the severity of post-irradiation sialadenitis.

Methods:

The development of the Sialadenitis Assessment Tool proceeded through three phases. The first and second phases included a literature review and the development of the tool which derived from the review, respectively. The third phase involved a pilot testing of the Assessment Tool to a sample of 34 patients undergoing I¹³¹ therapy. The assessment was carried out by two independent healthcare professionals, pre- and post-radioiodine therapy. The results of the assessment tool were compared with other scales, including the DIRIX and EORTC H&N35.

Results:

According to the Cohen’s kappa test, the Sialadenitis Assessment Tool is a reliable tool for the assessment of sialadenitis (Cohen’s κ = 1). The concurrent and internal validity tests showed a tendency of association with most variables (p < 0.001) in the DIRIX and EORTC QLQ-HN35 scales.

Conclusion:

Preliminary evidence show that Sialadenitis Assessment Tool is a valid and reliable tool to assess radioiodine-induced sialadenitis in patients undergoing I¹³¹ therapy post-thyroidectomy.

Assessment of early oxidative stress following the use of radiotheranostics agents 177Lu-PSMA for prostate cancer and 177Lu-DOTATATE for neuroendocrine tumors; radioprotective effect of vitamin C

BACKGROUND

We aimed first to evaluate the early oxidative stress following radionuclide therapy (RNT) with 177Lu-PSMA and 177Lu-DOTATATE and second to evaluate the protective effect of vitamin C on oxidative stress.

MATERIALS AND METHODS

Prostate cancer and neuroendocrine tumor (NET) patients referred to therapy with 177Lu-PSMA and 177Lu-DOTATATE, respectively, were enrolled in this study. The patients divided into the control group underwent routine RNT without any intervention and the intervention group was asked to take effervescent tablets (500 mg) of vitamin C for two days prior to the RNT (three tablets per day). To measure oxidative stress, blood samples were taken immediately before treatment and 48 h after treatment, and the serums were separated and frozen. To evaluate oxidative stress, the serum levels of malondialdehyde (MDA) and glutathione (GSH) and the activity of glutathione reductase were measured before and two days after treatment.

RESULTS

In total, 61 RNT cycles were evaluated in 34 patients with age of 65 ± 2.83 (median ± SE) years (range of 27-99); this total included 20 (59%) prostate cancer patients [35 cycles (57.4%)] and 14 patients (41%) with NET [26 cycles (42.6%)]. Of the 61 evaluated cycles, 27 cycles were given in the control group and 34 cycles were given in the intervention group. The serum level of MDA was significantly increased after treatment compared to before treatment (P = 0.02) in the control group, while no significant change in the serum level of MDA was observed in the intervention group (P = 0.52). The serum level of GSH was insignificantly decreased after treatment compared to before treatment in the control group and slightly increased after treatment in the intervention group (P > 0.05). The serum level of glutathione reductase was insignificantly increased in all groups of patients after treatment (P > 0.05).

CONCLUSION

According to the results of this study, RNT with Lu-PSMA and Lu-DOTATATE may induce oxidative stress via the generation of free radicals and reactive oxygen species. Consumption of vitamin C prior to RNT may ameliorate this oxidative stress. These preliminary results have positive implications for clinical practice. Verification of these noteworthy results is needed and can be conducted with larger randomized controlled trials with longer time points.

Salivary and lacrimal dysfunction after radioactive iodine for differentiated thyroid cancer: American Head and Neck Society Endocrine Surgery Section and Salivary Gland Section joint multidisciplinary clinical consensus statement of otolaryngology, ophthalmology, nuclear medicine and endocrinology

BACKGROUND

Postoperative radioactive iodine (RAI) administration is widely utilized in patients with differentiated thyroid cancer. While beneficial in select patients, it is critical to recognize the potential negative sequelae of this treatment. The prevention, diagnosis, and management of the salivary and lacrimal complications of RAI exposure are addressed in this consensus statement.

METHODS

A multidisciplinary panel of experts was convened under the auspices of the American Head and Neck Society Endocrine Surgery and Salivary Gland Sections. Following a comprehensive literature review to assess the current best evidence, this group developed six relevant consensus recommendations.

RESULTS

Consensus recommendations on RAI were made in the areas of patient assessment, optimal utilization, complication prevention, and complication management.

CONCLUSION

Salivary and lacrimal complications secondary to RAI exposure are common and need to be weighed when considering its use. The recommendations included in this statement provide direction for approaches to minimize and manage these complications.

MnTnBuOE-2-PyP treatment protects from radioactive iodine (I-131) treatment-related side effects in thyroid cancer

Treatment of differentiated thyroid cancer often involves administration of radioactive iodine (I-131) for remnant ablation or adjuvant therapy. However, there is morbidity associated with I-131 therapy, which can result in both acute and chronic complications. Currently, there are no approved radioprotectors that can be used in conjunction with I-131 to reduce complications in thyroid cancer therapy. It is well known that the damaging effects of ionizing radiation are mediated, in part, by the formation of reactive oxygen species (ROS). A potent scavenger of ROS, Mn(III)meso-tetrakis(N-n-butoxyethylpyridinium-2-yl)porphyrin (MnTnBuOE-2-PyP), has radioprotective and anti-tumor effects in various cancer models including head and neck, prostate, and brain tumors exposed to external beam radiation therapy. Female C57BL/6 mice were administered I-131 orally at doses of 0.0085-0.01 mCi/g (3.145 × 10⁵ to 3.7 × 10⁵ Bq) of body weight with or without MnTnBuOE-2-PyP. We measured acute external inflammation, blood cell counts, and collected thyroid tissue and salivary glands for histological examination. We found oral administration of I-131 caused an acute decrease in platelets and white blood cells, caused facial swelling, and loss of thyroid and salivary tissues. However, when MnTnBuOE-2-PyP was given during and after I-131 administration, blood cell counts remained in the normal range, less facial inflammation was observed, and the salivary glands were protected from radiation-induced killing. These data indicate that MnTnBuOE-2-PyP may be a potent radioprotector of salivary glands in thyroid cancer patients receiving I-131 therapy.

Effect of External Cooling on 177Lu-PSMA Uptake by the Parotid Glands

Recent years have seen the start of treatment of metastatic castration-resistant prostate cancer with prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (PRLT), especially ¹⁷⁷Lu-PSMA-617. However, PRLT has side effects on the salivary glands that limit the safety of the treatment. The current study aimed to show the effect of external cooling with ice packs on ¹⁷⁷Lu-PSMA-617 uptake by the parotid glands (PGs). Methods: The study included 19 patients (mean age, 72.9 y) with metastatic castration-resistant prostate cancer who had been referred for the first time for ¹⁷⁷Lu-PSMA-617 treatment and underwent pretreatment ⁶⁸Ga-PSMA-11 PET/CT. Before the initiation of PRLT, the SUV_max and SUV_mean of the right and left PGs were measured on ⁶⁸Ga-PSMA PET/CT. Frozen ice packs were then affixed over the right PG of each patient for approximately 5 h; 1 h after they were affixed, PRLT was administered. At 4 h after PRLT, head-and-neck SPECT/CT was performed, and at both 4 and 24 h after PRLT, whole-body planar scintigraphy was performed. Regions and volumes of interest were applied for the right and left PGs, and the counts and volumes were determined. Results: Before PRLT, ⁶⁸Ga-PSMA-11 PET/CT showed no significant difference in SUV_max or SUV_mean between the right and left PGs (P > 0.05). At 4 and 24 h after PRLT, planar imaging showed no significant difference in counts between the cooled and noncooled PGs (P > 0.05). Furthermore, at 4 h after PRLT, SPECT/CT showed no significant difference in counts or volumes between the cooled and noncooled PGs (P > 0.05). Conclusion: External cooling does not reduce uptake of ¹⁷⁷Lu-PSMA-617 by the PGs.

Pilocarpine effect on dose rate of salivary gland in differentiated thyroid carcinoma patients treated with radioiodine

OBJECTIVE

Although different methods have been suggested on reducing salivary gland radiation after radioiodine administration, an effective preventive or therapeutic measure is still up for debate. The aim of this study was to evaluate the effect of pilocarpine, as a sialagogue drug on the radioiodine content of the salivary gland, and radioiodine-induced symptoms of salivary gland dysfunction.

PATIENTS AND METHODS

Patients who were referred for radioiodine therapy were randomized into pilocarpine and placebo groups. The patients as well as the nurse who administered the tablets, and the specialist who analyzed the images, were all unaware of the patients' group. Anterior and posterior planar images including that of both the head and neck were obtained 2, 6, 12, 24, and 48 h after the administration of radioiodine in all patients, and round regions of interest were drawn for both left and right parotid glands, with a rectangular region of interest in the region of the cerebrum as background. All patients were interrogated once, 6 months after radioiodine administration, by a phone call for subjective evaluation of symptoms related to salivary gland damage.

RESULTS

There was no significant difference between the two groups with regard to the mean age, sex, and initial iodine activity. The geometric mean of background-corrected count per administered dose and acquisition time was calculated for the bilateral parotid glands. This normalized parotid count showed a significant reduction in net parotid count in both groups during the first 48 h after radioiodine administration. However, no significant difference was found between the groups according to the amount and pattern of dose reduction in this time period.

CONCLUSION

This study revealed that pilocarpine had no significant effect on the radioiodine content of parotid glands during the first 48 h after radioiodine administration. No significant difference was found in the incidence of symptoms between the two groups treated with placebo and pilocarpine.

The evaluation of protective and mitigating effects of vitamin C against side effects induced by radioiodine therapy

The goal of this study was to evaluate the protective and mitigative effect of vitamin C on oxidative stress in differentiated thyroid cancer (DTC) patients ablated with radioiodine. 58 DTC patients selected for radioactive iodine therapy (RAIT) with 5550 MBq ¹³¹Iodine were divided into four groups. Group 1 (control group) consisted of patients who underwent RAIT routinely. Other patients received 1500 mg vitamin C daily 2 days after (group 2), 2 days before to 2 days after (group 3) and 2 days before RAIT (group 4). Serum oxidative stress markers including malondialdehyde (MDA), glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) were measured immediately before and 2 days after RAIT. A significant increase in MDA after RAIT was observed in all groups (p < 0.05). The concentrations of MDA were significantly higher in the control group compared to the intervention groups (p < 0.05). A significant decrease in the control group (p < 0.05) and increase in group 4 (p < 0.05) were observed in GSH level after RAIT (p < 0.05). Mean variation of GSH was significant between control group with groups 3 (p < 0.01) and 4 (p < 0.01). The results indicate that activity of SOD remained unchanged in all groups (p > 0.05). A significant increase was observed in CAT activity after RAIT in all groups (p < 0.05), which was higher in control group than intervention groups. In groups 3 (p < 0.05) and 4 (p < 0.05), this increase in CAT activity was significantly lower than the control group. RAIT causes serum oxidative stress, which can be ameliorated using vitamin C as an antioxidant. These results indicate that radioprotective effect of vitamin C is preferable to its mitigative effect.

Radioprotective effect of vitamin E on salivary glands after radioiodine therapy for differentiated thyroid cancer: a randomized-controlled trial

OBJECTIVES

This study aimed to examine the radioprotective effect of vitamin E on salivary glands after radioactive iodine (I) therapy in patients with differentiated thyroid cancer.

PATIENTS AND METHODS

Eighty-two patients with differentiated thyroid cancer were enrolled in this study. They were divided randomly into four groups (control group: 22 cases, group A: 23 cases, group B: 22 cases, and group C: 15 cases) before postsurgical ablation therapy with 100 mCi I. The patients in groups A, B, and C received vitamin E 100, 200, and 300 mg/day orally, respectively, for a duration of 1 week before to 4 weeks after I therapy. Salivary gland function was assessed using salivary gland scintigraphy immediately before and 6 months after I therapy. Uptake fraction (UF), uptake index (UI), excretion fraction (EF), and excretion ratio (ER) of each salivary gland were measured and compared.

RESULTS

On comparison between before and after I therapy in the control group, there was a significant decrease in UF of both right and left parotid glands (all P<0.01). In group A, a significant increase in EF of the right parotid gland (P<0.01) and UI of the right submandibular gland (P<0.05) was found. In group B, there was a significant increase in UI of the right parotid gland and both submandibular glands (all P<0.01). In group C, there was a significant increase in UF of the left parotid gland (P<0.05) and the right submandibular gland (P<0.01). Also, there was a statistical increase in UI in both submandibular glands (all P<0.01). However, on comparing the changes in the post-I therapy salivary scintigraphy parameters among the four groups, there was a significant difference in ΔUI of the right parotid gland (P<0.05) and both submandibular glands (all P<0.01), as well as ΔER of the left parotid gland (P<0.05) and ΔUF of the left submandibular gland (P<0.05).

CONCLUSION

Vitamin E exerts significant protective effects on the parotid and submandibular glands after I therapy.

The effect of chewing-gum on dose rate of salivary gland in differentiated thyroid carcinoma patients treated with radioiodine

BACKGROUND

Although, different methods have been suggested on reducing salivary gland radiation after radioiodine administration, an effective preventive or therapeutic measure is still debated. To the best of our knowledge this is the second study that aimed to evaluate the effect of chewing-gum as a sialagogue on the radioiodine content of salivary gland, and radioiodine-induced symptoms of salivary gland dysfunction.

METHODS

Twenty-two patients who were referred to radioiodine therapy were randomized into chewing-gum (group A) and control (group B) groups. Anterior and posterior planar images including both head and neck were obtained 2, 6, 12, 24 and 48 hours after the administration of radioiodine in all patients and round regions of interest (ROI) were drawn for both left and right parotid glands with a rectangular ROI in the region of cerebrum as the background. All patients were followed once, 6 months after radioiodine administration via a phone call for subjective evaluation of symptoms related to salivary gland damage.

RESULTS

There was no significant difference between the two groups regarding the mean age, gender and initial iodine activity. The geometric mean of background-corrected count per administrated dose and acquisition time was calculated for bilateral parotid glands. This normalized parotid count showed a significant reduction in net parotid count in both groups during the first 48 hours after the radioiodine administration. However, no significant difference was found between the groups according to the amount and pattern of dose reduction in this time period.

CONCLUSIONS

This study revealed that chewing-gum had no significant effect on the radioiodine content of parotid glands during the first 48 hours after radioiodine administration. Also, no significant difference was found in the incidence of relevant symptoms after 6 months comparing both groups.

Proton change of parotid glands after gustatory stimulation examined by magnetic resonance imaging

The aim of this study was to investigate proton changes of the parotid gland after gustatory stimulation by semi-quantitative parameters and an empirical mathematical model (EMM) using high-temporal-resolution, double-echo, echo-planar imaging (EPI). Approved by a local institutional review board, this study examined 20 parotid glands from 10 healthy volunteers (male:female = 6: 4; age ± standard deviation =35.1 ± 14.1 years) with written informed consent obtained. All participants underwent 1.5-T, double-echo EPI with gustatory stimulation. Semi-quantitative parameters, including maximal drop ratio (MDR), time to peak (TTP), drop slope (DS), recovery slope (RS) and recovery ratio (RR), were calculated. The effect of temporal resolution on parotid functional parameters was evaluated. An EMM comprising an output function ( Sot=Aoe-kot+B) and an input function ( Sint=Ain1-e-kint) was also applied to fit all dynamic curves. Kruskal-Wallis test, Wilcoxon test, linear regression analysis and goodness of fit were used for statistical analysis. p < 0.05 was considered to be statistically significant. The signal intensity dropped significantly after gustatory stimulation on the proton density (PD) image (p < 0.01). MDR was 8.26% in the PD image. MDR and RR were negatively associated with time interval, whereas DS and TTP were significantly positively associated with time interval (all p < 0.05). EMM parametric values derived from PD-time curves of parotid glands were 12.04 ± 6.81%, 6.43 ± 4.23 min^-1 , 88.73 ± 6.18%, 8.41 ± 4.86 min^-1 and 1.09 ± 1.35 for A_o , k_o , B, A_in and k_in , respectively. Semi-quantitative functional parameters and EMM parameters using high-temporal-resolution, double-echo EPI allow the quantification of parotid proton changes after gustatory stimulation.

Seeking Optimal Management for Radioactive Iodine Therapy-induced Adverse Effects

Radioactive iodine therapy (RAIT) is one of the important treatment modalities in the management of differentiated thyroid cancer (DTC). RAIT with iodine-131 has long been used in the management of DTC for the ablation of residual thyroid or treatment of its metastases. Despite being reasonably safe, radioiodine therapy is not always without side effects. Even relatively low administered activities of RAIT used for remnant ablation have been associated with the more clinically significant side effects of sialadenitis, xerostomia, salivary gland pain and swelling, dry eyes, excessive tearing, or alterations in taste in as many as 25% of patients. Given that there is a lack of comprehensive management of these RAIT-induced adverse effects, this paper explores the use of other nonpharmacological measures and their effectiveness as interventions to minimize salivary gland damage.

Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy

BACKGROUND

Salivary gland dysfunction is an 'umbrella' term for the presence of either xerostomia (subjective sensation of dryness), or salivary gland hypofunction (reduction in saliva production). It is a predictable side effect of radiotherapy to the head and neck region, and is associated with a significant impairment of quality of life. A wide range of pharmacological interventions, with varying mechanisms of action, have been used for the prevention of radiation-induced salivary gland dysfunction.

OBJECTIVES

To assess the effects of pharmacological interventions for the prevention of radiation-induced salivary gland dysfunction.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 14 September 2016); the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 8) in the Cochrane Library (searched 14 September 2016); MEDLINE Ovid (1946 to 14 September 2016); Embase Ovid (1980 to 14 September 2016); CINAHL EBSCO (Cumulative Index to Nursing and Allied Health Literature; 1937 to 14 September 2016); LILACS BIREME Virtual Health Library (Latin American and Caribbean Health Science Information database; 1982 to 14 September 2016); Zetoc Conference Proceedings (1993 to 14 September 2016); and OpenGrey (1997 to 14 September 2016). We searched the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included randomised controlled trials, irrespective of their language of publication or publication status. Trials included participants of all ages, ethnic origin and gender, scheduled to receive radiotherapy on its own or in addition to chemotherapy to the head and neck region. Participants could be outpatients or inpatients. We included trials comparing any pharmacological agent regimen, prescribed prophylactically for salivary gland dysfunction prior to or during radiotherapy, with placebo, no intervention or an alternative pharmacological intervention. Comparisons of radiation techniques were excluded.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 39 studies that randomised 3520 participants; the number of participants analysed varied by outcome and time point. The studies were ordered into 14 separate comparisons with meta-analysis only being possible in three of those.We found low-quality evidence to show that amifostine, when compared to a placebo or no treatment control, might reduce the risk of moderate to severe xerostomia (grade 2 or higher on a 0 to 4 scale) at the end of radiotherapy (risk ratio (RR) 0.35, 95% confidence interval (CI) 0.19 to 0.67; P = 0.001, 3 studies, 119 participants), and up to three months after radiotherapy (RR 0.66, 95% CI 0.48 to 0.92; P = 0.01, 5 studies, 687 participants), but there is insufficient evidence that the effect is sustained up to 12 months after radiotherapy (RR 0.70, 95% CI 0.40 to 1.23; P = 0.21, 7 studies, 682 participants). We found very low-quality evidence that amifostine increased unstimulated salivary flow rate up to 12 months after radiotherapy, both in terms of mg of saliva per 5 minutes (mean difference (MD) 0.32, 95% CI 0.09 to 0.55; P = 0.006, 1 study, 27 participants), and incidence of producing greater than 0.1 g of saliva over 5 minutes (RR 1.45, 95% CI 1.13 to 1.86; P = 0.004, 1 study, 175 participants). However, there was insufficient evidence to show a difference when looking at stimulated salivary flow rates. There was insufficient (very low-quality) evidence to show that amifostine compromised the effects of cancer treatment when looking at survival measures. There was some very low-quality evidence of a small benefit for amifostine in terms of quality of life (10-point scale) at 12 months after radiotherapy (MD 0.70, 95% CI 0.20 to 1.20; P = 0.006, 1 study, 180 participants), but insufficient evidence at the end of and up to three months postradiotherapy. A further study showed no evidence of a difference at 6, 12, 18 and 24 months postradiotherapy. There was low-quality evidence that amifostine is associated with increases in: vomiting (RR 4.90, 95% CI 2.87 to 8.38; P < 0.00001, 5 studies, 601 participants); hypotension (RR 9.20, 95% CI 2.84 to 29.83; P = 0.0002, 3 studies, 376 participants); nausea (RR 2.60, 95% CI 1.81 to 3.74; P < 0.00001, 4 studies, 556 participants); and allergic response (RR 7.51, 95% CI 1.40 to 40.39; P = 0.02, 3 studies, 524 participants).We found insufficient evidence (that was of very low quality) to determine whether or not pilocarpine performed better or worse than a placebo or no treatment control for the outcomes: xerostomia, salivary flow rate, survival, and quality of life. There was some low-quality evidence that pilocarpine was associated with an increase in sweating (RR 2.98, 95% CI 1.43 to 6.22; P = 0.004, 5 studies, 389 participants).We found insufficient evidence to determine whether or not palifermin performed better or worse than placebo for: xerostomia (low quality); survival (moderate quality); and any adverse effects.There was also insufficient evidence to determine the effects of the following interventions: biperiden plus pilocarpine, Chinese medicines, bethanechol, artificial saliva, selenium, antiseptic mouthrinse, antimicrobial lozenge, polaprezinc, azulene rinse, and Venalot Depot (coumarin plus troxerutin).

AUTHORS' CONCLUSIONS

There is some low-quality evidence to suggest that amifostine prevents the feeling of dry mouth in people receiving radiotherapy to the head and neck (with or without chemotherapy) in the short- (end of radiotherapy) to medium-term (three months postradiotherapy). However, it is less clear whether or not this effect is sustained to 12 months postradiotherapy. The benefits of amifostine should be weighed against its high cost and side effects. There was insufficient evidence to show that any other intervention is beneficial.

Effects of first radioiodine ablation on functions of salivary glands in patients with differentiated thyroid cancer

The aim of this study was to evaluate the effects of the first radioactive iodine (I) therapy on functions of salivary glands in patients with differentiated thyroid carcinoma (DTC).There were 36 consented patients with DTC enrolled in this study, who received 3.7 GBq (100mCi) I for ablation after total thyroidectomy. Salivary gland function was assessed using salivary gland scintigraphy in two phases, one 4 hours before and the other 6 months after I therapy (both under thyrotropin stimulation condition). Quantitative parameters including uptake fraction (UF), uptake index (UI), excretion fraction (EF), and excretion ratio (ER) were measured and compared. Blood parameters were also compared. Associations between sex and outcome of the first I therapy as well as individual salivary gland function were measured. Wilcoxon Signed Rank Sum test and χ test were used for statistical analysis.When compared between pre-ablation and post-ablation, UF of bilateral parotid and submandibular glands were significantly increased (all P < .01). UI of both submandibular glands were significantly increased (P < .05). This seemingly increased uptake function after the first I therapy was actually compensatory mechanism of salivary gland, which indicated a possible intermediate state after radiation. But salivary glands' secretory function had not changed significantly except for left submandibular gland; we demonstrated that only left submandibular gland showed significantly decreased ER (P < .05). Thyroglobulin and thyroglobulin antibody significantly decreased after I therapy (P < .05). There were no sex differences on therapeutic outcome and salivary gland dysfunctions after the first I therapy. Salivary gland of both males and females could be affected by I therapy.The first I ablative therapy may impair the salivary uptake and secretory function of patients with DTC. There was no association between sex and salivary gland dysfunction.

Production and Clinical Applications of Radiopharmaceuticals and Medical Radioisotopes in Iran

During past 3 decades, nuclear medicine has flourished as vibrant and independent medical specialty in Iran. Since that time, more than 200 nuclear physicians have been trained and now practicing in nearly 158 centers throughout the country. In the same period, Tc-99m generators and variety of cold kits for conventional nuclear medicine were locally produced for the first time. Local production has continued to mature in robust manner while fulfilling international standards. To meet the ever-growing demand at the national level and with international achievements in mind, work for production of other Tc-99m-based peptides such as ubiquicidin, bombesin, octreotide, and more recently a kit formulation for Tc-99m TRODAT-1 for clinical use was introduced. Other than the Tehran Research Reactor, the oldest facility active in production of medical radioisotopes, there is one commercial and three hospital-based cyclotrons currently operational in the country. I-131 has been one of the oldest radioisotope produced in Iran and traditionally used for treatment of thyrotoxicosis and differentiated thyroid carcinoma. Since 2009, (131)I-meta-iodobenzylguanidine has been locally available for diagnostic applications. Gallium-67 citrate, thallium-201 thallous chloride, and Indium-111 in the form of DTPA and Oxine are among the early cyclotron-produced tracers available in Iran for about 2 decades. Rb-81/Kr-81m generator has been available for pulmonary ventilation studies since 1996. Experimental production of PET radiopharmaceuticals began in 1998. This work has culminated with development and optimization of the high-scale production line of (18)F-FDG shortly after installation of PET/CT scanner in 2012. In the field of therapy, other than the use of old timers such as I-131 and different forms of P-32, there has been quite a significant advancement in production and application of therapeutic radiopharmaceuticals in recent years. Application of (131)I-meta-iodobenzylguanidine for treatment of neuroblastoma, pheochromocytoma, and other neuroendocrine tumors has been steadily increasing in major academic university hospitals. Also (153)Sm-EDTMP, (177)Lu-EDTMP, (90)Y-citrate, (90)Y-hydroxyapatite colloid, (188/186)Re-sulfur colloid, and (188/186)Re-HEDP have been locally developed and now routinely available for bone pain palliation and radiosynovectomy. Cu-64 has been available to the nuclear medicine community for some time. With recent reports in diagnostic and therapeutic applications of this agent especially in the field of oncology, we anticipate an expansion in production and availability. The initiation of the production line for gallium-68 generator is one of the latest exciting developments. We are proud that Iran would be joining the club of few nations with production lines for this type of generator. There are also quite a number of SPECT and PET tracers at research and preclinical stage of development preliminarily introduced for possible future clinical applications. Availability of fluorine-18 tracers and gallium-68 generators would no doubt allow rapid dissemination of PET/CT practices in various parts of our large country even far from a cyclotron facility. Also, local production and availability of therapeutic radiopharmaceuticals are going to open exciting horizons in the field of nuclear medicine therapy. Given the available manpower, local infrastructure of SPECT imaging, and rapidly growing population, the production of Tc-99m generators and cold kit would continue to flourish in Iran.

Clinical Studies of Nonpharmacological Methods to Minimize Salivary Gland Damage after Radioiodine Therapy of Differentiated Thyroid Carcinoma: Systematic Review

Purpose. To systematically review clinical studies examining the effectiveness of nonpharmacological methods to prevent/minimize salivary gland damage due to radioiodine treatment of differentiated thyroid carcinoma (DTC). Methods. Reports on relevant trials were identified by searching the PubMed, CINHAL, Cochrane, and Scopus electronic databases covering the period 01/2000–10/2015. Inclusion/exclusion criteria were prespecified. Search yielded eight studies that were reviewed by four of the present authors. Results. Nonpharmacological methods used in trials may reduce salivary gland damage induced by radioiodine. Sialogogues such as lemon candy, vitamin E, lemon juice, and lemon slice reduced such damage significantly (p < 0.0001, p < 0.05, p < 0.10, and p < 0.05, resp.). Parotid gland massage also reduced the salivary damage significantly (p < 0.001). Additionally, vitamin C had some limited effect (p = 0.37), whereas no effect was present in the case of chewing gum (p = 0.99). Conclusion. The review showed that, among nonpharmacological interventions, sialogogues and parotid gland massage had the greatest impact on reducing salivary damage induced by radioiodine therapy of DTC. However, the studies retrieved were limited in number, sample size, strength of evidence, and generalizability. More randomized controlled trials of these methods with multicenter scope and larger sample sizes will provide more systematic and reliable results allowing more definitive conclusions.

Radioiodine-induced oxidative stress in patients with differentiated thyroid carcinoma and effect of supplementation with vitamins C and E and selenium (antioxidants)

OBJECTIVE

The objective of this study, in addition to confirming that therapy with 131I causes oxidative stress, was to evaluate the effect of supplementation with vitamins C and E and selenium on this phenomenon by measuring plasma 8-epi-PGF2a, a marker of lipid peroxidation.

SUBJECTS AND METHODS

Forty patients with thyroid cancer submitted to thyroidectomy, who received 3.7 GBq 131I after levothyroxine withdrawal, were selected; 20 patients did not receive (control group) and 20 patients received (intervention group) daily supplementation consisting of 2000 mg vitamin C, 1000 mg vitamin E and 400 µg selenium for 21 days before 131I. Plasma 8-epi-PGF2a was measured immediately before and 2 and 7 days after 131I.

RESULTS

A significant increase in plasma 8-epi-PGF2a after 131I was observed in the two groups. The concentrations of 8-epi-PGF2α were significantly higher in the control group before and 2 and 7 days after 131I. The percentage of patients with elevated 8-epi-PGF2α was also significantly higher in the control group before and after 131I. Furthermore, the increase (percent) in 8-epi-PGF2α was significantly greater in the control group (average of 112.3% versus 56.3%). Only two patients (10%) reported side effects during supplementation.

CONCLUSIONS

Ablation with 131I causes oxidative stress which can be minimized by the use of antioxidants.