Evidence for early and persistent impairment of salivary gland excretion after irradiation of head and neck tumours

Salivary toxicity from PSMA-targeted radiopharmaceuticals: What we have learned and where we are going

Clinical trials of prostate-specific membrane antigen (PSMA) targeted radiopharmaceuticals have shown encouraging results. Some agents, like lutetium-177 [177Lu]Lu-PSMA-617 ([177Lu]Lu-PSMA-617), are already approved for late line treatment of metastatic castration-resistant prostate cancer (mCRPC). Projections are for continued growth of this treatment modality; [177Lu]Lu-PSMA-617 is being studied both in earlier stages of disease and in combination with other anti-cancer therapies. Further, the drug development pipeline is deep with variations of PSMA-targeting radionuclides, including higher energy alpha particles conjugated to PSMA-honing vectors. It is safe to assume that an increasing number of patients will be exposed to PSMA-targeted radiopharmaceuticals during the course of their cancer treatment. In this setting, it is important to better understand and mitigate the most commonly encountered toxicities. One particularly vexing side effect is xerostomia. In this review, we discuss the scope of the problem, inventories to better characterize and monitor this troublesome side effect, and approaches to preserve salivary function and effectively palliate symptoms. This article aims to serve as a useful reference for prescribers of PSMA-targeted radiopharmaceuticals, while also commenting on areas of missing data and opportunities for future research.

Will Nigella sativa oil protect parotid glands of rats against cranium gamma irradiation? Histological and immunohistochemical evaluation

BACKGROUND

Radiation plays an essential role in treating malignancies. Radiation exposure of salivary glands often results in permanent loss of their functions; therefore, their protection against radiation is crucial. Nigella sativa oil (NSO) is a useful antioxidant against free radicals. The purpose of this study was to investigate the radio-protective effect of NSO on oxidative injury of parotid glands of gamma-irradiated rats.

METHODS

Twenty-eight male albino rats were divided into four groups (n = 7): Group 1: Neither NSO nor radiation, Group 2: Rats received NSO 400 mg/kg, Group 3: Rats received 15 Gy cranium gamma irradiation & Group 4: Rats received gamma irradiation and NSO. Rats were sacrificed two weeks after the last NSO dose. Histological sections of parotid glands were stained with H&E, Masson's trichrome and anti-TGF-β antibodies. Area percentage of Masson's trichrome and TGF-β expression was morphometrically examined.

RESULTS

Parotid glands of control and NSO groups revealed normal morphology. Gamma-irradiated glands showed loss of normal acinar architecture and slight acinar shrinkage. NSO treatment of gamma-irradiated glands preserved acinar outline and architecture. Masson's trichrome stained samples revealed trace amounts of collagen fibers in control and NSO groups, and excessive amounts of collagen fibers in gamma-irradiated group, in addition to few collagen fibers for gamma-irradiated glands treated with NSO. Additionally, control and NSO groups showed negative TGF-β expression. Gamma-irradiated group showed high TGF-β expression, while NSO treated gamma-irradiated group showed moderate TGF-β expression.

CONCLUSIONS

Gamma-irradiation adversely affected parotid glands, and in contrast, NSO seemed to positively counteract this adverse effect.

Early Quantification of Salivary Gland Function after Radioiodine Therapy

Purpose of the Study:

Radioiodine (I-131) is used as an effective noninvasive treatment for thyroid malignancies. Salivary gland is one of the most affected nontarget organs. The present study aims to perform early quantification of salivary gland function after I-131 therapy (RIT) for thyroid cancer considering I-131 down-scatter in the Tc-99m window.

Materials and Methods:

A total of 20 patients (6 males and 14 females) with differentiated thyroid carcinoma were enrolled in the study. Baseline dynamic salivary scintigraphy was performed in all patients using 185–370 MBq (5–10 mCi) Tc-99m pertechnetate. Posttherapy, salivary scintigraphy was performed 10–25 days after RIT in the range of 1.85–7.4 GBq (50–200 mCi). Time–activity curves obtained from the pre- and posttherapy dynamic salivary scintigraphy were used for semi-quantitative analysis. Uptake ratio (UR), ejection fraction (EF%), and maximum accumulation (MA%) were calculated by drawing regions of interest of individual parotid and submandibular glands over a composite image, after correcting for down-scatter from I-131 in the Tc-99m window. A paired t-test was used for comparison of the parameters obtained.

Results:

Significant changes were observed in UR and EF% of both parotid and submandibular glands (P < 0.05). No significant changes were found in the value of MA% of left parotid gland and both submandibular glands in the posttherapy scans in comparison to pretherapy scans (P > 0.05). However, significant difference was observed in the MA% of the right parotid gland (P = 0.025).

Conclusion:

Salivary gland function was found to deteriorate after RIT, with the parotid glands affected more than the submandibular glands.

Parotid gland stem cells: Mini yet mighty

BACKGROUND

Our aim was to evaluate the correlation between the radiation doses to parotid gland (PG) stem cells and xerostomia.

METHODS

Patients diagnosed with head and neck cancer (HNC) were retrospectively evaluated, and xerostomia inventory (XI) was applied to these patients. PG stem cells were delineated on the treatment planning CT, and the mean doses to the PG stem cells calculated.

RESULTS

The total test score and mean doses to bilateral PGs were significantly correlated (r = .34, P = .001), and the mean doses to bilateral PG stem cell niches were significantly correlated with the total test score (r = .32, P = .002).

CONCLUSIONS

In this study, we found that the mean dose to PG stem cells can predict dry mouth as much as the mean dose to the PG.

Potential Applications of 68Ga-PSMA-11 PET/CT in the Evaluation of Salivary Gland Uptake Function: Preliminary Observations and Comparison with 99mTcO4 - Salivary Gland Scintigraphy

Purpose

To preliminarily evaluate the feasibility and potential of using ⁶⁸Ga-PSMA-11 PET/CT in evaluating the function of salivary glands and lacrimal glands in comparison with ^99mTc-pertechnetate (^99mTcO₄⁻) salivary gland scintigraphy (SGS).

Methods

A retrospective study was performed in 15 patients with different degrees of xerostomia and suspected salivary gland dysfunction. Each patient underwent ⁶⁸Ga-PSMA-11 PET/CT first and SGS the next day, and the findings of both scans were compared.

Results

The results of ⁶⁸Ga-PSMA-11 PET/CT and SGS were consistent in 12/15 patients (80%) and were inconsistent in the remaining patients (20%). For 5 (33.3%) of 15 patients, ⁶⁸Ga-PSMA-11 PET/CT provided more information than did SGS. Additionally, ⁶⁸Ga-PSMA-11 PET/CT corrected the misdiagnosis by SGS for 1 patient.

Conclusions

⁶⁸Ga-PSMA-11 PET/CT is a potentially useful imaging tool for evaluating the function of salivary glands and lacrimal glands. ⁶⁸Ga-PSMA-11 PET/CT can be a promising supplement to SGS, and its clinical value deserves further study.

Protective effects of alpha lipoic acid on radiation-induced salivary gland injury in rats

Purpose

Radiation therapy is a treatment for patients with head and neck (HN) cancer. However, radiation exposure to the HN often induces salivary gland (SG) dysfunction. We investigated the effect of α-lipoic acid (ALA) on radiation-induced SG injury in rats.

Results

ALA preserved acinoductal integrity and acinar cell secretary function following irradiation. These results are related to the mechanisms by which ALA inhibits oxidative stress by inhibiting gp91 mRNA and 8-OHdG expression and apoptosis of acinar cells and ductal cells by inactivating MAPKs in the early period and expression of inflammation-related factors including NF-κB, IκB-α, and TGF-β1 and fibrosis in late irradiated SG. ALA effects began in the acute phase and persisted for at least 56 days after irradiation.

Materials and Methods

Rats were assigned to followings: control, ALA only (100 mg/kg, i.p.), irradiated, and ALA administered 24 h and 30 min prior to irradiation. The neck area including the SG was evenly irradiated with 2 Gy per minute (total dose, 18 Gy) using a photon 6-MV linear accelerator. Rats were killed at 4, 7, 28, and 56 days after radiation.

Conclusions

Our results show that ALA could be used to ameliorate radiation-induced SG injury in patients with HN cancer.

Radioprotective effects of pyrroloquinoline quinone on parotid glands in C57BL/6J mice

The aim of the present study was to investigate whether pyrroloquinoline quinine (PQQ) serve a radioprotective role in parotid gland damage induced by total body irradiation (TBI) in C57BL/6J mice. A total of 15 female 8-week-old C57BL/6J mice were randomly assigned into three treatment groups: i) Untreated control (no irradiation); ii) 4 gray (Gy) X-ray irradiation; iii) 4 Gy X-ray irradiation with additional dietary PQQ (4 mg PQQ/kg in normal diet). Each group included five mice. After 4 weeks, all animals were collected for evaluating the phenotype, body weight, pathological and biochemical parameters. The results indicated that PQQ had biological effects on total body phenotype. PQQ could partially rescue TBI-induced damage to parotid glands. In addition, PQQ served radioprotective effects on parotid glands via multiple mechanisms, such as promoting proliferation, inhibiting apoptosis and senescence, upregulating antioxidant ability, scavenging reactive oxygen species and reducing DNA damage. The results of the present study demonstrate that PQQ serves a radioprotective role in parotid gland damage induced by TBI, possibly via inhibiting oxidative stress and participating in DNA damage repair. The study provides experimental and theoretical knowledge for the development of radioprotective clinical drugs.

Non-contrast-enhanced computed tomography attenuation in the parotid glands before radioiodine therapy for thyroid carcinoma could be a predictor of radiovulnerability

OBJECTIVE

This study aimed to determine a predictive factor for the effect of radioiodine therapy (RIT) on salivary gland dysfunction through a multiple regression analysis.

METHODS

We retrospectively assessed 40 patients with thyroid carcinoma, including 13 men (age range, 21-80 years) and 27 women (age range, 28-75 years), who underwent total thyroidectomy and were treated with RIT. We used multiple regression analysis to evaluate whether factors such as age, sex, dose number, prescintigraphy grade, computed tomography (CT) attenuation, and CT volume of the salivary glands affected the postscintigraphy grade. Receiver operating characteristics analysis was performed for predicting worsening scintigraphy grade of the parotid glands in 20 patients after RIT.

RESULTS

The postscintigraphy grade of the parotid glands was positively associated with the dose number and prescintigraphy grade and negatively associated with CT attenuation (β=0.48, P<0.01; β=0.47, P<0.01; and β=-0.26, P<0.05, respectively; adjusted R2=0.50, P<0.05). In the submandibular glands, the postscintigraphy grade was only positively correlated with dose number (β=0.58, P<0.01; adjusted R=0.32, P<0.01). Area under the curve was 0.775 (P<0.05) and the cutoff CT attenuation was -18.8 HU (sensitivity 0.714 and specificity 0.846).

CONCLUSION

The RIT dose number, prescintigraphy grade, and CT attenuation may be important predictors of parotid gland dysfunction after RIT, whereas the dose number alone may be a significant predictor of submandibular gland dysfunction.

Is Pilocarpine Effective in Preventing Radiation-Induced Xerostomia? A Systematic Review and Meta-analysis

PURPOSE

To evaluate the efficacy of concomitant administration of pilocarpine on radiation-induced xerostomia in patients with head and neck cancers.

METHODS AND MATERIALS

The PubMed, Web of Science, Cochrane Library, and ClinicalTrials were searched to identify randomized, controlled trials studying the effect of concomitant administration of pilocarpine for radiation-induced xerostomia. Included trials were systematically reviewed, and quantifiable outcomes were pooled for meta-analysis. Outcomes of interest included salivary flow, clinician-rated xerostomia grade, patient-reported xerostomia scoring, quality of life, and adverse effects.

RESULTS

Six prospective, randomized, controlled trials in 8 articles were included in this systematic review. The total number of patients was 369 in the pilocarpine group and 367 in the control group. Concomitant administration of pilocarpine during radiation could increase the unstimulated salivary flow rate in a period of 3 to 6 months after treatment, and also reduce the clinician-rated xerostomia grade. Patient-reported xerostomia was not significantly impacted by pilocarpine in the initial 3 months but was superior at 6 months. No significant difference of stimulated salivary flow rate could be confirmed between the 2 arms. Adverse effects of pilocarpine were mild and tolerable.

CONCLUSIONS

The concomitant administration of pilocarpine during radiation increases unstimulated salivary flow rate and reduces clinician-rated xerostomia grade after radiation. It also relieves patients' xerostomia at 6 months and possibly at 12 months. However, pilocarpine has no effect on stimulated salivary flow rate.

Late oral complications following radiotherapy for head and neck cancers

Radiotherapy is an important treatment modality for head and neck cancers, both as definitive treatment and as adjunct treatment after surgery. Complications are common after radiotherapy for head and neck cancer owing to irradiation of many normal tissues and structures with important functions related to daily activities. Of these, late oral complications are of particular concern because of their effect on many basic functions, such as speech and swallowing. Although late complications following radiotherapy have been recognized for many years, recent developments in the treatment of head and neck cancers may have a significant impact on the incidence and severity of late complications. This article examines the current issue of late oral complications after radiotherapy, with an emphasis on the impact of recent advances in cancer treatment.

Salivary gland sparing in the treatment of head and neck cancer

Radiotherapy is an important component of the multimodality treatment of head and neck cancer. Although an effective treatment for many patients, it can have significant long-term sequelae. In particular, xerostomia - or dry mouth - caused by salivary gland injury is a serious problem suffered by most patients and leads to problems with oral comfort, dental health, speech and swallowing. This article explores the mechanisms behind radiation injury to the major salivary glands, as well as different strategies to minimize and alleviate xerostomia. This includes technical approaches to minimize radiation dose to salivary tissue, such as intensity-modulated radiotherapy and surgical transfer of salivary glands, as well as pharmacologic approaches to stimulate or protect the salivary tissue. The scientific literature will be critically examined to see what works and what strategies have been less effective in attempting to minimize xerostomia in head and neck cancer patients.

Evaluation of Salivary Gland Dysfunction Using Salivary Gland Scintigraphy in Sjögren's Syndrome Patients and in Thyroid Cancer Patients after Radioactive Iodine Therapy

PURPOSE

Salivary gland scintigraphy (SGS) provides an objective means of diagnosing salivary gland dysfunction in Sjögren's syndrome (SS) patients and in thyroid cancer patients after radioactive iodine (RAI) therapy. In the present study, SGS was performed in SS patients and in thyroid cancer patients post-RAI, and scintigraphic parameters were compared.

METHODS

Twenty-eight SS patients (males:females = 1:27, age 53.3 ± 11.9 years), 28 controls (males:females = 3:25, age 54.1 ± 10.1 years), and 92 thyroid cancer patients (males:females = 28:64, age 46.2 ± 12.9) who had undergone a session of high-dose RAI therapy (mean dose, 5.2 ± 1.5 GBq) were included. SGS was performed using Tc-99m pertechnetate (925 MBq). Scintigraphic parameters (parotid uptake ratio PU, submandibular uptake ratio SU, percentage parotid excretion %PE, and percentage submandibular excretion %SE) were measured and compared for SS, thyroid cancer post-RAI, and control patients.

RESULTS

PU, SU, %SE, and %PE were all significantly lower in SS than in post-RAI thyroid cancer or control patients (p < 0.05), whereas only %PE was significantly lower in post-RAI thyroid cancer patients than in controls (p < 0.05). SU and %SE were found to be correlated with the unstimulated whole salivary flow rate.

CONCLUSION

Scintigraphic parameters derived from SGS can play a crucial role in the detection of salivary gland dysfunction in SS patients and in post-RAI thyroid cancer patients.

Assessment of post-radiotherapy salivary glands

Salivary glands are usually irradiated during radiotherapy for head and neck cancers, which can lead to radiation-induced damage. Radiation-induced xerostomia (oral dryness) is the most common post-radiotherapy complication for head and neck cancer patients and can reduce the patient's quality of life. Accurate and efficient salivary gland assessment methods provide a better understanding of the cause and degree of xerostomia, and may help in patient management. At present, there are different methods for the assessment of salivary gland hypofunction; however, none of them are considered to be standard procedure. This article reviews the value of common methods in the assessment of post-radiotherapy salivary glands.

Innervation and secretory function of transplanted human submandibular salivary glands

Free submandibular gland autotransplantation is used to treat absolute tear deficiency. Although disconnected from any peripheral innervation, most transplants show increasing secretion for years. We have evaluated the secretory activity and autonomic innervation of such transplants. Secretory activity of glands in response to parasympatholytics and parasympathomimetics was evaluated by Schirmer's test and Technetium scintigraphy. Submandibular gland tissue specimens taken before and after transplantation were examined histologically. Relative hypersecretion during the first postoperative week suddenly decreased but then slowly increased during the first postoperative year. Hypersecretion was significantly reduced by parasympatholytics while carbachol rapidly increased secretion. Histology of transplanted glandular tissue showed parenchymal atrophy. Cholinesterase-positive nerves were abundant and in a similar distribution to normal with scattered positive ganglion cells. Adrenergic axons were fewer than normal and irregularly distributed. Early hypersecretion may be due to release of neurotransmitters from degenerating terminal axons. This is followed by a period of minimal secretion during which hypersensitivity of acinar cells develops. With spontaneous reinnervation, secretion is accentuated by external sympathetic vasomotor adrenergic drive. This shows that submandibular glands can remain viable despite complete separation from their normal nerve supply and are capable of regaining a substantial secretory activity for years.

Impact of Radiation-Induced Xerostomia on Quality of Life After Primary Radiotherapy Among Patients With Head and Neck Cancer

PURPOSE

To investigate the impact of xerostomia on overall quality of life (QoL) outcome and related dimensions among head and neck cancer patients treated with primary radiotherapy.

METHODS AND MATERIALS

A total of 288 patients with Stage I-IV disease without distant metastases were included. Late xerostomia according to the Radiation Therapy Oncology Group (RTOG-xerostomia) and QoL (European Organization for Research and Treatment of Cancer QLC-C30) were assessed at baseline and every 6th month from 6 months to 24 months after radiotherapy.

RESULTS

A significant association was found between RTOG-xerostomia and overall QoL outcome (effect size [ES] 0.07, p < 0.001). A significant relationship with global QoL, all functioning scales, and fatigue and insomnia was observed. A significant interaction term was present between RTOG-xerostomia and gender and between RTOG-xerostomia and age. In terms of gender, RTOG-xerostomia had a larger impact on overall QoL outcome in women (ES 0.13 for women vs. 0.07 for men). Furthermore, in women ES on individual scales were larger, and a marked worsening was observed with increasing RTOG-xerostomia. No different ES according to age was seen (ES 0.10 for 18-65 years vs. 0.08 for >65 years). An analysis of the impact of RTOG-xerostomia on overall QoL outcome over time showed an increase from 0.09 at 6 months to 0.22 at 24 months. With elapsing time, a worsening was found for these individual scales with increasing RTOG-xerostomia.

CONCLUSIONS

The results of this prospective study are the first to show a significant impact of radiation-induced xerostomia on QoL. Although the incidence of Grade > or =2 RTOG-xerostomia decreases with time, its impact on QoL increases. This finding emphasizes the importance of prevention of xerostomia.

Assessment of salivary function change in nasopharyngeal carcinoma treated by parotid-sparing radiotherapy

PURPOSE

The purpose of this study was to evaluate function of major salivary glands, subjective xerostomia, and correlation between subjective and objective xerostomia scoring after precision-oriented radiotherapy for nasopharyngeal carcinoma.

MATERIALS AND METHODS

From 2000 to 2002, 34 patients with histologically proven non-metastatic nasopharyngeal carcinoma received definitive therapy by parotid-sparing radiotherapy, which included intensity-modulated radiotherapy (33 patients>60 Gy), 3D-conformal radiotherapy, and brachytherapy boost. Salivary function was assessed by sialoscintigraphy pre-irradiation and post-irradiation at 1, 6, 12, and 18 months. The salivary stimulated secretion ratio (SSR) was used to evaluate function of submandibular and parotid glands. Subjective and objective xerostomia was monitored by the LENT/SOMA system.

RESULTS

The median dose to parotid gland was 34.6 Gy (interquartile range, 32.9-36.5 Gy). The median dose to submandibular gland was 60.5 Gy (interquartile range, 58.1-61.5 Gy). Parotid-gland post-irradiation median SSR at 1 (0.01, P=0.000) and 6 (0.08, P=0.002) months showed significant reduction compared with pre-irradiation data (0.30). After 12 months, parotid-gland median SSR (12 months, 0.22, P = 0.734; 18 months, 0.16, P=0.885) lost significance compared with pre-irradiation data. Submandibular-gland post-irradiation median SSR at 1 (P=0.000), 6 (P=0.000), 12 (P=0.000), and 18 (P=0.000) months all showed significant reduction compared with pre-irradiation data. There were significant correlations between LENT/SOMA subjective and objective xerostomia scores at 6 months (r=0.657, P=0.000), 12 months (r=0.480, P=0.013), and 18 months (r=0.591, P=0.002).

CONCLUSIONS

With parotid-sparing radiotherapy for nasopharyngeal carcinoma, gland function can recover significantly 12 months after radiotherapy. There were significant rank-order correlations between LENT/SOMA subjective and objective (analytic) grading scores at 6 to 18 months' follow-up.

Longitudinal scintigraphic study of parotid and submandibular gland function after total body irradiation in children and adolescents

OBJECTIVE

Total body irradiation (TBI) and cyclophosphamide (CY) during allogeneic stem cell transplantation (ASCT) cause salivary gland dysfunction in children. The aim of this investigation was to study the scintigraphic functional changes over time of the parotid and submandibular glands in children and young adults one year after treatment with CY and TBI at ASCT.

METHODS

Salivary gland scintigraphy (SGS) was performed before ASCT, and 3-6 months and 12 months after ASCT. The three male patients who fulfilled the scintigraphic study had a mean age (+/- SD) of 17.3 +/- 9.8 years at ASCT.

RESULTS

The parotid secretion capacity (SPar) was 83.5 +/- 3.2% before ASCT and 48.5 +/- 25.8% during the next 3-6 months (P < 0.05). The SPar did not increase (48.1 +/- 12.4%) during the rest of the first year after ASCT. The submandibular emptying capacity (SSub) was 91.3 +/- 12.9% before ASCT and 35.4 +/- 2.3% after 3-6 months (P < 0.05). The SSub was 87.9 +/- 17.9% one year after ASCT.

CONCLUSIONS

The parotid glands were more sensitive to irradiation since they did not recover lost capacity to secrete saliva, while the submandibular glands recovered the secretion capacity at the one-year follow-up.

Can dose reduction to one parotid gland prevent xerostomia?--A feasibility study for locally advanced head and neck cancer patients treated with intensity-modulated radiotherapy

AIMS

Dryness of the mouth is one of the most distressing chronic toxicities of radiation therapy in head and neck cancers. In this study, parotid function was assessed in patients with locally advanced head and neck cancers undergoing intensity-modulated radiotherapy (IMRT) with or without chemotherapy. Parotid function was assessed with the help of a questionnaire and parotid scintigraphy, especially with regards to unilateral sparing of the parotid gland.

MATERIALS AND METHODS

In total, 19 patients were treated with compensator-based IMRT between February 2003 and March 2004. The dose to the clinical target volume ranged between 66 and 70 Gy in 30-35 fractions to 95% of the isodose volume. Ipsilateral high-risk neck nodes received an average dose of 60 Gy and the contralateral low-risk neck received a dose of 54-56 Gy. Eight of 19 patients also received concomitant chemotherapy.

RESULTS

Subjective toxicity to the parotid glands was assessed with the help of a questionnaire at 0, 3 and 6 months and objective toxicity was assessed with parotid scintigraphy at 0 and 3 months. The mean dose to the ipsilateral parotid gland ranged from 19.5 to 52.8 Gy (mean 33.14 Gy) and the mean dose to the contralateral gland was 11.1-46.6 Gy (mean 26.85 Gy). At a median follow-up of 13 months, 9/19 patients had no symptoms of dryness of the mouth (grade I), 8/19 had mild dryness of the mouth (grade II) and only 2/19 had grade III xerostomia, although the parotid gland could only be spared on one side in most of the patients.

CONCLUSIONS

Minimising the radiation dose to one of the parotid glands with the help of IMRT in patients with advanced head and neck cancers can prevent xerostomia in most patients and parotid scintigraphy is a useful method of documenting xerostomia.

Radiotherapy alone, versus radiotherapy with amifostine 3 times weekly, versus radiotherapy with amifostine 5 times weekly: A prospective randomized study in squamous cell head and neck cancer

BACKGROUND

The main objective of this study was to investigate whether nondaily intravenous administration of amifostine was as effective as daily intravenous administration with regard to the reduction of the incidence of Grade 2 or greater xerostomia in patients with head and neck cancer.

METHODS

Ninety-one patients who received bilateral irradiation for head and neck cancer were included. Thirty patients received no amifostine (AMI-0), 31 patients received amifostine at a dose of 200 mg/m2 3 times weekly (AMI-3), and 30 patients received amifostine at a dose of 200 mg/m2 daily (5 times weekly) (AMI-5). Acute and late xerostomia and quality of life (QOL) were assessed at baseline, 6 weeks later, and at 6-month intervals from 6 months to 24 months postradiotherapy.

RESULTS

Grade 2 or greater late xerostomia differed significantly at 6 months (AMI-0 74% vs. AMI-3 67% vs. AMI-5 52%; P = .03), but not thereafter. During follow-up, patient-rated xerostomia deteriorated more in AMI-0 patients (mean difference score:, 52 for AMI-0 compared with 25 for AMI-3, and 29 for AMI-5; P = .01). Nausea and emesis were reported most frequently as side effect, but Grade 2 or greater toxicity was observed in only 4 patients. However, 28% of patients discontinued amifostine before the end of radiotherapy.

CONCLUSIONS

Long-term, patient-rated xerostomia was less for the AMI-3 and AMI-5 groups through 2-year follow-up, but no difference was noted between the AMI-3 and AMI-5 groups. For late xerostomia according to the Radiation Therapy Oncology Group criteria, the same effect was observed at 6 months, but not thereafter.

Factors influencing the parotid function in nasopharyngeal carcinoma treated with parotid-sparing radiotherapy

BACKGROUND

To evaluate the factors influencing post-irradiation parotid gland function in nasopharyngeal cancer treated with parotid-sparing radiotherapy.

METHODS

This study consisted of 45 patients with nasopharyngeal cancer treated with radiotherapy including 3D conformal radiotherapy, intensity-modulated radiotherapy and high-dose-rate brachytherapy. The mean follow-up time was 37.5 months (range: 15-50 months). Objective parotid gland function was assessed by series sialoscintigraphy pre-irradiation and post-irradiation at 1, 6, 12 and 18 months. Subjective salivary function was recorded by the LENT/SOMA system. Wilcoxon signed-rank test was used to compare the secretion ratio (SR) of parotid gland before and after treatment. Mann-Whitney rank-sum test was used to determine the factors influencing the post-irradiated SR. Chi-square test was used to compare the correlation between subjective grading of xerostomia and objective grading of parotid glands.

RESULTS

There was a significant difference between the pre-irradiation and post-irradiation parotid gland's SR at 1 (0.30 versus 0.01, P < 0.05) and 6 months (0.03 versus 0.08, P < 0.05). However, there was no significant difference compared with the pre-irradiation SR at 12 (0.30 versus 0.20, P > 0.05) and 18 months (0.30 versus 0.18, P > 0.05). There was significant correlation between subjective and objective salivary function (P = 0.024) at 12 months after radiotherapy. The factor that impacted the preservation of parotid function was mean dose to the parotid gland >38.0 Gy (P < 0.05).

CONCLUSIONS

Our results demonstrated that parotid function could recover 1 year after treatment with parotid-sparing radiotherapy in patients with nasopharyngeal cancer. The most important factor that influenced parotid function was the mean dose to the parotid gland.

MDM2 is required for suppression of apoptosis by activated Akt1 in salivary acinar cells

Chronic damage to the salivary glands is a common side effect following head and neck irradiation. It is hypothesized that irreversible damage to the salivary glands occurs immediately after radiation; however, previous studies with rat models have not shown a causal role for apoptosis in radiation-induced injury. We report that etoposide and gamma irradiation induce apoptosis of salivary acinar cells from FVB control mice in vitro and in vivo; however, apoptosis is reduced in transgenic mice expressing a constitutively activated mutant of Akt1 (myr-Akt1). Expression of myr-Akt1 in the salivary glands results in a significant reduction in phosphorylation of p53 at serine(18), total p53 protein accumulation, and p21(WAF1) or Bax mRNA following etoposide or gamma irradiation of primary salivary acinar cells. The reduced level of p53 protein in myr-Akt1 salivary glands corresponds with an increase in MDM2 phosphorylation in vivo, suggesting that the Akt/MDM2/p53 pathway is responsible for suppression of apoptosis. Dominant-negative Akt blocked phosphorylation of MDM2 in salivary acinar cells from myr-Akt1 transgenic mice. Reduction of MDM2 levels in myr-Akt1 primary salivary acinar cells with small interfering RNA increases the levels of p53 protein and renders these cells susceptible to etoposide-induced apoptosis in spite of the presence of activated Akt1. These results indicate that MDM2 is a critical substrate of activated Akt1 in the suppression of p53-dependent apoptosis in vivo.

Quantitative evaluation of salivary gland dysfunction after radioiodine therapy using salivary gland scintigraphy

AIM

The most frequent non-thyroidal complication of high-dose (131)I therapy for thyroid carcinoma is salivary gland dysfunction, which may be transient or permanent. In this study, we assessed radioiodine-induced permanent salivary gland dysfunction using quantitative salivary gland scintigraphy.

METHODS

Salivary scintigraphy was performed with (99m)Tc-pertechnetate on 50 thyroid carcinoma patients who had been given radioiodine for thyroid ablation; 20 normal subjects were imaged as the control population. Dynamic scintigraphy was performed and time-activity curves for four major salivary glands were generated. The glandular functional parameters maximum secretion, time at maximum count and uptake ratio of the parotid and submandibular glands were calculated. Correlation of the administered dose and subjective symptoms with findings of salivary gland scintigraphy was evaluated.

RESULTS

The maximum secretion and uptake ratio were decreased in 46% and 42% of patients who received radioiodine therapy, respectively. Salivary gland dysfunction correlated well with the administered dose. The parotid glands were more affected than the submandibular glands. Fifty-two per cent of patients were symptomatic, 69.23% of whom showed salivary gland dysfunction.

CONCLUSION

Parenchymal damage to the salivary glands induced by radioactive iodine treatment can be evaluated by salivary gland scintigraphy. The impairment was worse in parotid glands and increased with the total dose. The maximum secretion and uptake ratio were found to be sufficiently sensitive to distinguish the severity of the damage.

Effects of gender and age on the quantitative parameters of [99mTc]pertechnetate salivary gland scintigraphy in normal subjects

AIM

To assess the effect of gender and age on [99mTc]pertechnetate salivary gland scintigraphy (SGS) in healthy subjects.

METHODS

The study population consisted of 93 normal subjects (46 women, 47 men; age range 20-59 years). The subjects were categorized into eight (four female and four male) subgroups according to age decades. Dynamic SGS was performed after intravenous injection of 370 MBq [99mTc]pertechnetate. Anterior salivary gland images were acquired for 30 min. On the basis of the time-activity curves, three functional parameters were calculated for the parotid and submandibular salivary glands: (1) the first minute uptake ratio, (2) the maximum uptake ratio, and (3) the maximum secretion percentage.

RESULTS

For women, all parotid and submandibular functional parameters had a peak in the fourth decade group. The comparison of four age groups in the female subjects showed significant differences, except for the third versus the fifth decades, at least for one parameter. The number of significant differences was highest in the comparison between the second versus the fourth decades. Among men, the highest values for all parotid and submandibular parameters were in the second decade, except for the first minute uptake ratio in the submandibular gland. The number of parameters that were significantly different among the four age groups in men was lower than in women. The first minute uptake ratio of the submandibular gland had the most significant differences among the groups of male subjects.

CONCLUSION

Age and gender differences have a significant effect on salivary gland functions which is more apparent in women than in men.

Parotid-sparing radiotherapy: does it really reduce xerostomia?

AIMS

Parotid-sparing radiotherapy (PSRT) was introduced for patients with selected head and neck cancer requiring bilateral upper-neck irradiation at our centre in 2000. The aim of this study was to compare the subjective degree of xerostomia in patients treated with PSRT between January 2000 and June 2003 with patients treated using conventional techniques (radiotherapy) over the same period.

MATERIALS AND METHODS

Eligible patients were required to have completed treatment 6 months previously and be recurrence-free at the time of interview. PSRT was defined as conformal radiotherapy, in which the mean dose to at least one parotid gland was 33 Gy or less, as determined by the dose-volume histogram. Patients receiving radiotherapy were treated with standard parallel-opposed fields, such that both parotids received a minimum of 40 Gy. Xerostomia was assessed using a validated questionnaire containing six questions with a rating between 0 and 10. Lower scores indicated less difficulty with xerostomia.

RESULTS

Thirty-eight eligible patients treated with PSRT were identified: 25 with oropharyngeal cancer and 13 with nasopharyngeal cancer (NPC). The mean overall questionnaire score (Q1-5) for this group was 4.20 (standard error = 0.33). Forty-four patients (24 oropharyngeal, 21 NPC) treated with radiotherapy over the same period were eligible. The mean overall questionnaire score (Q1-5) for this group was 5.86 (standard error = 0.35). The difference in mean overall scores between the two groups of patients was statistically significant (P < 0.001), as were the scores for four of the six individual questions.

CONCLUSION

These results suggest that PSRT offers improved long-term xerostomia-related quality of life compared with conventional radiotherapy.

Does radiation dose to the salivary glands and oral cavity predict patient-rated xerostomia and sticky saliva in head and neck cancer patients treated with curative radiotherapy?

BACKGROUND AND PURPOSE

To investigate the association between the mean salivary gland and oral cavity dose, with patient-rated moderate and severe xerostomia and sticky saliva.

PATIENTS AND METHODS

One hundred and fifty-seven patients treated with bilateral irradiation for head and neck cancer were included. The parotid and submandibular glands and the oral cavity were delineated on plannings-CT scans. At baseline and 6 and 12 months self-reported xerostomia and sticky saliva were assessed using the EORTC QLQ-H&N35 questionnaire.

RESULTS

At 6 months a significant association between the mean parotid (MD(par)) and mean submandibular dose (MD(subm)) and xerostomia was observed (OR - MD(par): 1.17; P=0.002 and OR - MD(subm): 1.08; P = 0.02). Between MD(par) and MD(subm), a significant interaction term was present. No significant association was found with the oral cavity dose. Xerostomia was reversible depending on MD(par) and MD(subm). Considering Sticky saliva, a significant association was found at 6 and 12 months with MD(subm) (OR: 1.03; P < 0.001). The P50 for sticky saliva increased with elapsing time.

CONCLUSIONS

Both MD(par) and MD(subm) influence the risk of xerostomia in irradiated patients at 6 months. This probability as a function of the mean parotid dose significantly depended on the mean dose in the submandibular glands. Sticky saliva mainly depends on MD(subm).

On the mechanism of salivary gland radiosensitivity

PURPOSE

To contribute to the understanding of the enigmatic radiosensitivity of the salivary glands by analysis of appropriate literature, especially with respect to mechanisms of action of early radiation damage, and to supply information on the possibilities of amelioration of radiation damage to the salivary glands after radiotherapy of head-and-neck cancer.

METHODS AND MATERIALS

Selected published data on the mechanism of salivary gland radiosensitivity and radioprotection were studied and analyzed.

RESULTS

From a classical point of view, the salivary glands should not respond as rapidly to radiation as they appear to do. Next to the suggestion of massive apoptosis, the leakage of granules and subsequent lysis of acinar cells was suggested to be responsible for the acute radiation-induced function loss of the salivary glands. The main problem with these hypotheses is that recently performed assays show no cell loss during the first days after irradiation, while saliva flow is dramatically diminished. The water secretion is selectively hampered during the first days after single-dose irradiation. Literature is discussed that shows that the compromised cells suffer selective radiation damage to the plasma membrane, disturbing signal transduction primarily affecting watery secretion. Although the cellular composition of the submandibular gland and the parotid gland are different, the damage response is very alike. The acute radiation-induced function loss in both salivary glands can be ameliorated by prophylactic treatment with specific receptor agonists.

CONCLUSIONS

The most probable mechanism of action, explaining the enigmatic high radiosensitivity for early effects, is selective radiation damage to the plasma membrane of the secretory cells, disturbing muscarinic receptor stimulated watery secretion. Later damage is mainly due to classical mitotic cell death of progenitor cells, leading to a hampered replacement capacity of the gland for secretory cells, but is also caused by damage to the extracellular environment, preventing proper cell functioning.

Parotid secretory granules: crossroads of secretory pathways and protein storage

Saliva plays an important role in digestion, host defense, and lubrication. The parotid gland contributes a variety of secretory proteins-including amylase, proline-rich proteins, and parotid secretory protein (PSP)-to these functions. The regulated secretion of salivary proteins ensures the availability of the correct mix of salivary proteins when needed. In addition, the major salivary glands are targets for gene therapy protocols aimed at targeting therapeutic proteins either to the oral cavity or to circulation. To be successful, such protocols must be based on a solid understanding of protein trafficking in salivary gland cells. In this paper, model systems available to study the secretion of salivary proteins are reviewed. Parotid secretory proteins are stored in large dense-core secretory granules that undergo stimulated secretion in response to extracellular stimulation. Secretory proteins that are not stored in large secretory granules are secreted by either the minor regulated secretory pathway, constitutive secretory pathways (apical or basolateral), or the constitutive-like secretory pathway. It is proposed that the maturing secretory granules act as a distribution center for secretory proteins in salivary acinar cells. Protein distribution or sorting is thought to involve their selective retention during secretory granule maturation. Unlike regulated secretory proteins in other cell types, salivary proteins do not exhibit calcium-induced aggregation. Instead, sulfated proteoglycans play a role in the storage of secretory proteins in parotid acinar cells. This work suggests that unique sorting and retention mechanisms are responsible for the distribution of secretory proteins to different secretory pathways from the maturing secretory granules in parotid acinar cells.

Xerostomia Following Radiotherapy of the Head and Neck Affects Vocal Function

Purpose

To investigate whether xerostomia induced by wide-field radiotherapy (RT) of the head and neck affects vocal function.

Patients and Methods

We conducted a retrospective cohort study comparing 20 patients with early glottic cancer treated by limited RT of the larynx to 20 patients receiving wide-field RT of the primary tumor site and the lymphatic system of the entire head and neck, including the salivary glands. Salivary and vocal functions, as well as responses to questionnaires on xerostomia and quality of life were compared between groups. Twenty healthy volunteers matched for age, sex, and smoking status were included as controls.

Results

The wide-field RT patients showed high xerostomia-related symptom scores and significantly lower values of whole salivary flow rate compared to the limited RT and healthy patients (P < .001). Subjective vocal dysfunction and stroboscopic abnormality were observed in the wide-field RT group (P < .05), but acoustic or aerodynamic profiles showed no significant difference among groups (P > .05). Subjective and objective salivary gland hypofunction was significantly correlated to vocal dysfunction.

Conclusion

Our results suggest that xerostomia following extensive RT of the head and neck can affect vocal function. In the treatment of head and neck malignancies, efforts to prevent post-RT xerostomia would be anticipated to contribute to the preservation of vocal function.

Dose-response relationships within the parotid gland after radiotherapy for head and neck cancer

BACKGROUND AND PURPOSE

To determine the salivary function, after parotid-sparing radiotherapy (RT), of different regions within the parotid gland and to evaluate dose-function relationships within the parotid glands and between patients.

PATIENTS AND METHODS

Sixteen head and neck cancer patients, irradiated between September 1999 and November 2000 using a conformal parotid-sparing technique, were included in this study. Before RT and 7 months after RT (range 6-10 months), a salivary gland scintigraphy was performed in all patients combined with a single photon emission computed tomography (SPECT). The salivary excretion fraction (SEF) was measured, after stimulation, in 8-12 transverse 5mm SPECT slices of each parotid. Loss of salivary excretion fraction (dSEF %) of these slices was calculated as the proportion of SEF after RT as compared to SEF before RT. Since the planning CT-scan and the SPECT-scintigraphy were performed in the same treatment position, the dose to a transverse slice within the parotid gland could be matched to the loss of salivary excretion fraction of that respective slice. A non-linear model was fitted to the dose-loss of function data and the dose resulting in 50% loss of salivary excretion fraction (D50) was calculated.

RESULTS

Before RT, all but one patient presented with normal salivary excretion fractions (SEF) of both parotid glands. Within the same parotid gland, the SEF's of the different slices were almost equal. Seven months after RT, the reduction in SEF was statistically significant (P-value<0.0001). A significant difference in loss of salivary excretion fraction (dSEF) was also observed between both parotid glands (P<0.0001) as a result of the parotid-sparing technique. When plotting the dSEF of a slice versus the dose given to that slice, doses as low as 10-15 Gy could result in a serious loss of function (dSEF>50%). After fitting a non-linear model to these plots, the mean dose resulting in 50% loss of salivary excretion fraction (D50) 7 months after RT was 22.5 Gy. A large inter-patient variability was found in D50.

CONCLUSIONS

Salivary SPECT is a useful tool for the evaluation of the salivary function of different slices within the parotid gland. Before irradiation, the different slices within one parotid gland act as functional sub-units contributing equally to the function of the entire gland. Seven months after an average dose of 22.5 Gy (D50) the functional sub-unit has lost 50% of its excretion fraction. The high inter-patient variability in D50 and the observation that low doses (10-15 Gy) can induce serious loss of function should prompt us in the clinic to reduce the dose to the parotids even lower than the threshold of 22.5 Gy.

Recurrences after conformal parotid-sparing radiotherapy for head and neck cancer

BACKGROUND AND PURPOSE

Evaluation of loco-regional failure patterns and survival after parotid-sparing three-dimensional conformal and intensity modulated radiotherapy (IMRT) for head and neck cancer.

PATIENTS AND METHODS

From June 1999 to July 2002, seventy-two patients with lateralised head and neck tumours, excluding nasopharyngeal tumours and patients with bilateral or contralateral neck disease, were irradiated with a parotid-sparing technique. Three-dimensional conformal planning was used in 68 patients, 4 patients were treated with dynamic IMRT. Bilateral neck node irradiation was performed in all patients, the junctional (or high level II) nodes, contralateral to the tumour, however, were excluded from the clinical target volume to spare the adjacent parotid from irradiation. In 20 patients with persistent or recurrent loco-regional disease, the localisation and volume of the treatment failure, as determined by computed tomography (CT), was copied on the pre-treatment CT-study used for treatment planning. Minimum, mean and maximum doses administered to the region of the failure were calculated and dose--volume histograms were computed of each failure. The failures were divided in three groups depending on the percentage of their volume receiving 95% of the prescribed dose. Recurrences were defined to be in-field (IF) if >95% of their volume received 95% of the prescribed dose and out-field (OF) if <20% of their volume received 95% of the prescribed dose. When 20-95% of the volume of the recurrence received 95% of the prescribed dose, this recurrence was defined as extending outside the field (EOF).

RESULTS

With a median follow-up time of 19 months, the 2-year loco-regional control rate was 69% with primary radiotherapy and 63.5% with surgery followed by irradiation (P = 0.77). The 2-year overall survival rate for the entire patient population was 67.4%. At the time of analysis, 20 of the 72 patients had developed a loco-regional failure; 2 patients (2/20) presented with a loco-regional relapse combined with distant metastasis. Fifteen of the 20 loco-regional failures (15/20) occurred within the high dose region (IF). Five patients (5/20) developed a failure of which the bulky tumour mass was located within the high dose region but extending outside the treatment volume (EOF). No relapses were seen out-field (OF) and no patients relapsed in the spared junctional area contralateral to the tumour.

CONCLUSIONS

The selection of patients treated with parotid-sparing radiotherapy, by omitting irradiation to the junctional nodes contralateral to the tumour, proved to be safe in our hands, since no recurrences developed in the spared area. As this parotid-sparing technique reduces significantly the dose to the contralateral parotid and is easy to perform, it should be considered for all selected patients.

Scintigraphic assessment of early and late parotid gland function after radiotherapy for head-and-neck cancer: a prospective study of dose-volume response relationships

PURPOSE

To investigate the value of scintigraphy as an indirect measurement of parotid function after radiotherapy (RT).

METHODS AND MATERIALS

Ninety-six patients with primary or postoperative RT for various malignancies in the head-and-neck region were prospectively evaluated. Parotid gland scintigraphy was performed before RT and 6 weeks and 1 year after RT. The uptake, excretion fraction of the saliva from the parotid gland to the oral cavity (SEF), and the ratios of uptake and SEF after and before treatment were calculated. CT-based treatment planning was used to derive dose-volume histograms of the parotid glands. To establish the effects of both the radiation dose and the volume of the parotid gland irradiated, the normal tissue complication probability model proposed by Lyman was fit to the data.

RESULTS

The mean maximal uptake of 192 parotid glands decreased significantly from 3329 counts (ct)-/s before RT to 3084 ct/s and 3005 ct/s at 6 weeks and 1 year after RT. The SEF before treatment was 44.7%. The SEF decreased to 18.7% at 6 weeks after RT, but recovered to a SEF of 32.4% at 1 year after RT. A significant correlation was found between the uptake 1 year after RT and the mean parotid dose. The reduction in post-RT SEF correlated significantly with the mean parotid gland dose. The normal tissue complication probability model parameter TD50 was found to be 29 and 43 Gy at 6 weeks and 1 year after RT, respectively, when a complication was defined as a posttreatment SEF parotid ratio of <45%.

CONCLUSIONS

The effects of radiation on parotid gland function using scintigraphy could be well established. A statistically significant correlation between the SEF ratio and the mean parotid dose was shown, with some recovery of function at 1 year after RT, comparable with the flow results. When direct flow measurements are not feasible, parotid scintigraphy appears to be a good indicator of gland function.

Intensity-modulated radiotherapy: Examples of its utility in head and neck cancer

Intensity-modulated radiotherapy (IMRT) has been available at Peter MaCallum Cancer Centre (PMCC) since November 2000. The present report illustrates two cases of our early experience with IMRT. Case 1 is a 66-year-old man with a T(1)N(2)M(0) nasopharyngeal carcinoma treated with chemo-radiotherapy using parotid-sparing IMRT. Fourteen months following treatment he remains in complete remission, with salivary function assessed using a xerostomia-specific quality of life questionnaire, having returned to near pretreatment levels by 12 months. Case 2 is a 70-year-old man with a T(4)N(0)M(0) base of tongue squamous cell carcinoma treated with chemo-radiotherapy after refusing radical surgery. He had received subtotal nodal irradiation to 36 Gy in 1994 for Hodgkins disease stage IIA. A radical dose was still achievable despite previous irradiation without exceeding unacceptable spinal cord dose with IMRT. He remains in complete remission 14 months from his initial presentation without evidence of neurological toxicity. Intensity-modulated radiotherapy allows sparing of critical normal structures in the head and neck without compromising dose to the tumour. It is, therefore, desirable for several clinical applications and essential in some, if unacceptable compromises are not to be made.

Evaluation of salivary gland function after treatment of head-and-neck tumors with intensity-modulated radiotherapy by quantitative pertechnetate scintigraphy

PURPOSE

To evaluate salivary gland function after inversely planned stereotactic intensity-modulated radiotherapy (IMRT) for tumors of the head-and-neck region using quantitative pertechnetate scintigraphy.

METHODS AND MATERIALS

Since January 2000, 18 patients undergoing IMRT for cancer of the head and neck underwent pre- and posttherapeutic scintigraphy to examine salivary gland function. The mean dose to the primary planning target volume was 61.5 Gy (range 50.4-73.2), and the median follow-up was 23 months. In all cases, the parotid glands were directly adjacent to the planning target volume. The treatment planning goal was for at least one parotid gland to receive a mean dose of <26 Gy. Two quantitative parameters (change in maximal uptake and change in the relative excretion rate before and after IMRT) characterizing the change in salivary gland function after radiotherapy were determined. These parameters were compared with respect to the dose thresholds of 26 and 30 Gy for the mean dose. In addition, dose-response curves were calculated.

RESULTS

Using IMRT, it was possible in 16 patients to reduce the dose for at least one parotid gland to < or =26 Gy. In 7 patients, protection of both parotid glands was possible. No recurrent disease adjacent to the protected parotid glands was observed. Using the Radiation Therapy Oncology Group/European Organization for the Research and Treatment of Cancer scoring system, only 3 patients had Grade 2 xerostomia. No greater toxicity was seen for the salivary glands. The change in the relative excretion rate was significantly greater, if the parotid glands received a mean dose of > or =26 Gy or > or =30 Gy. For the change in maximal uptake, a statistically significant difference was seen only for the parotid glands and a dose threshold of 30 Gy. For the end point of a reduction in the parotid excretion rate of >50% and 75%, the dose-response curves yielded a dose at 50% complication probability of 34.8 +/- 3.6 and 40.8 +/- 5.3 Gy, respectively.

CONCLUSION

Using IMRT, it is possible to protect the parotid glands and reduce the incidence and severity of xerostomia in patients. Doses <26-30 Gy significantly preserve salivary gland function. The results support the hypothesis that application of IMRT does not lead to increased local failure rates.

Utilidad de la pilocarpina como profiláctico de xerostomía en pacientes con cáncer de cabeza y cuello tratados con radioterapia. Valoración mediante gammagrafía y flujo salivar

AIM

To assess the utility of salivary gland scintigraphy and salivary flow to quantify salivary function and to evaluate the usefulness of pilocarpine in the treatment of radiation-induced xerestomia in head and neck cancer patients.

METHOD

Thirty two patients with head and neck tumor treated with radiotherapy (RDT) were studied. Patients were classified into two groups: pilocarpine group (P), that received prophylactic pilocarpine before RDT and during the first year after treatment. No pilocarpine group (NP) that received RDT without pilocarpine. Salivary gland scintigraphy and salivary flow were performed before RDT and during one year after treatment. Parotid and submaxillary uptake and excretion were calculated. Salivary flow after stimulation during five minutes was also obtained.

RESULTS

Uptake and excretion in both salivary glands decreased after RDT. There were no statistical differences comparing P and NP groups (p < 0.001). However, in group P a trend to recovery was observed in parotid uptake values at 12 months after treatment, but it was not statistically significant. In both groups the salivary flow decreased after RDT and a good correlation (r = 0.8) between salivary flow and submaxillary excretion and parotid excretion was found.

CONCLUSIONS

Salivary gland scintigraphy and salivary flow could be useful to evaluate salivary gland function in patients with head and neck irradiated tumors. Although better results on the salivary uptake at 12 months were noted, pilocarpine did not significantly improve salivary gland function.

Swallowing apnea as a function of airway closure

The purpose of this research was to ascertain whether the existence of swallowing apnea (SA) was the sole result of glottic closure or the result of its own neural mechanism. Forty individuals served as participants. Groups 1 and 2 consisted of 10 individuals with laryngectomy less than one year and 10 individuals greater than one year, respectively. Groups 3 and 4 comprised 20 individuals who were age- and gender-matched to Groups 1 and 2. SA duration (SAD) was acquired during saliva swallows and 10-, 15-, 20-, and 25-ml water boluses. A repeated measures ANOVA was performed to determine mean differences in SAD as a function of group and bolus volume. Significant main effects of group and bolus volume were found and a significant interaction of group x bolus volume was found. In post-hoc analyses, both groups with laryngectomy exhibited statistically longer SADs than control groups. In single-df comparisons, the laryngectomy group over one year exhibited significantly shorter SADs on smaller versus larger bolus volumes. Even though SA is theoretically no longer needed in individuals with laryngectomy, the presence of SA remained in both groups with laryngectomy. Thus, these results support the hypothesis that SA is the result of its own neural command.

Oral sequelae of head and neck radiotherapy

In addition to anti-tumor effects, ionizing radiation causes damage in normal tissues located in the radiation portals. Oral complications of radiotherapy in the head and neck region are the result of the deleterious effects of radiation on, e.g., salivary glands, oral mucosa, bone, dentition, masticatory musculature, and temporomandibular joints. The clinical consequences of radiotherapy include mucositis, hyposalivation, taste loss, osteoradionecrosis, radiation caries, and trismus. Mucositis and taste loss are reversible consequences that usually subside early post-irradiation, while hyposalivation is normally irreversible. Furthermore, the risk of developing radiation caries and osteoradionecrosis is a life-long threat. All these consequences form a heavy burden for the patients and have a tremendous impact on their quality of life during and after radiotherapy. In this review, the radiation-induced changes in healthy oral tissues and the resulting clinical consequences are discussed.

Comparison of radiosensitivity of rat parotid and submandibular glands after different radiation schedules

BACKGROUND AND PURPOSE

To investigate the radiosensitivity of rat parotid and submandibular gland functioning after local single dose, conventional fractionated and accelerated fractionated irradiation.

METHODS

The salivary glands of male albino Wistar rats were locally irradiated with a single dose (15 Gy) or a calculated (alpha/beta; 9.6) biological effective dose of fractionated irradiation equal to this, viz. conventional fractionation (32 Gy in 16 fractions of 2 Gy/day, five times/week) or accelerated fractionation (32 Gy in 16 fractions of 2 Gy, two fractions/day). Parotid and submandibular/sublingual saliva samples were collected by means of miniaturized Lashley cups before and up to 240 days after irradiation. Salivary flow rate, lag phase and amylase secretion were used as parameters for the assessment of salivary gland function. At the end of the experiments the animals were sacrificed and the glands processed for histopathological examination.

RESULTS

Up to 120 days after irradiation no differences were observed between the glands or between the different irradiation schedules. Beyond 120 days, however, the parotid gland performed better in flow rate and lag phase after fractionated irradiation, when compared to the submandibular gland. The observed differences in function corresponded with the observed late histopathological changes. The parotid gland contained more acinar cells and had a higher gland weight. No differences were observed between both fractionation schedules on each gland.

CONCLUSIONS

The main observation from this study is the higher radiosensitivity of the submandibular gland compared to the parotid gland for late effects after fractionated irradiation. This may have implications for the treatment planning in case of radiotherapy for head and neck cancer.

The enigmatic mechanism of irradiation-induced damage to the major salivary glands

Irradiation is a central treatment modality administered for head and neck malignancies. Its major and most devastating side-effect is an induced damage to the major salivary glands. This article aims at suggesting a comprehensive explanation for the underlying mechanism of this damage, which has been considered as enigmatic throughout the 90 years since it was first described in 1911. The mechanism suggested is based on the considerable literature concerning this enigma in rat salivary glands. According to this proposed mechanism, the irradiation results in a sublethal DNA damage, which manifests and becomes lethal at a delayed phase. Thus, when the acinar progenitor cells are going through a reproductive phase when parenchymal replenishment is required, they die. The injurious agents, which result in this delayed reproductive cell death, appear to be highly redox-active transition metal ions, such as iron and copper. These metal ions, which seem to be associated with secretion granules, are not necessarily contained within the granules as previously suggested, but rather are probably located at sites more proximal to the DNA.

Salivary function in patients with chronic renal failure undergoing hemodialysis

PURPOSE

The aim of this study was to evaluate the changes in salivary gland function in patients with chronic renal failure (CRF) undergoing hemodialysis.

METHODS

The group consisted of 23 patients with CRF (13 female, 10 male; mean age: 40 +/- 13 yr) and 14 healthy control subjects (mean age: 40 +/- 13 yr). All underwent dynamic salivary gland scintigraphy with gustatory stimulation. After intravenous administration of 99mTc pertechnetate, first, perfusion images at 2 seconds per frame were acquired for 1 minute, then dynamic images at 1 minute per frame were acquired for 45 minutes. At 30 minutes after injection, 10 ml lemon juice was given for 15 minutes as a gustatory stimulus. We obtained time-activity curves derived from regions of interest centered over the four major salivary glands. The following functional indices were calculated for each gland: the time of maximum radioactivity (Tmax) for the prestimulated period, the time of minimum radioactivity (Tmin), as an indicator of velocity of secretion after stimulation, and the Lem E5% value as an indicator of the secretion function.

RESULTS

When the patients with CRF undergoing hemodialysis were compared to the controls, there were statistically significant differences in Tmax, Tmin and Lem E5% values for bilateral parotid glands, and Tmin values for bilateral submandibular glands (p < 0.05), there were no statistically significant differences in Tmax and Lem E5% values for bilateral submandibular glands. There were also significant differences in Tmax and Lem E5% values for bilateral parotid glands between mild oral problems and severe oral problems in patients with CRF (undergoing hemodialysis).

CONCLUSION

In this study, prolonged Tmax and Tmin values, and decreased Lem E5% values for parotid glands and prolonged Tmin values for submandibular glands on salivary scintigraphy pointed out decreased parenchymatous and excretory function in patients with CRF undergoing hemodialysis.

Parotid and submandibular/sublingual salivary flow during high dose radiotherapy

It was studied whether differences in acute radiosensitivity exist between parotid and submandibular/sublingual glands. The results revealed that salivary flow rates decreased dramatically during the first 2 weeks of radiotherapy. Neither recovery nor significant differences were observed between the production of saliva from the parotid and submandibular/sublingual glands during the 13 weeks observation period.

Xerostomia and its predictors following parotid-sparing irradiation of head-and-neck cancer

PURPOSE

To assess long-term xerostomia in patients receiving parotid-sparing radiation therapy (RT) for head-and-neck cancer, and to find the patient and therapy-related factors that affect its severity.

PATIENTS AND METHODS

From March 1994 through January 2000, 84 patients received comprehensive bilateral neck RT using conformal and multisegmental intensity-modulated RT (IMRT) aiming to spare the major salivary glands. Before RT and periodically through 2 years after the completion of RT, salivary flow rates from each of the major salivary glands were selectively measured. At the same time intervals, each patient completed an 8-item self-reported xerostomia-specific questionnaire (XQ). To gain a relative measure of the effect of RT on the minor salivary glands, whose output could not be measured, the surfaces of the oral cavity (extending to include the surface of the base of tongue) were outlined in the planning CT scans. The mean doses to the new organ ("oral cavity") were recorded. Forty-eight patients receiving unilateral neck RT were similarly studied and served as a benchmark for comparison. Factors predicting the XQ scores were analyzed using a random-effects model.

RESULTS

The XQ was found to be reliable and valid in measuring patient-reported xerostomia. The spared salivary glands which had received moderate doses in the bilateral RT group recovered to their baseline salivary flow rates during the second year after RT, and the spared glands in the unilateral RT group, which had received very low doses, demonstrated increased salivary production beyond their pre-RT levels. The increase in the salivary flow rates during the second year after RT paralleled an improvement in xerostomia in both patient groups. The improvement in xerostomia was faster in the unilateral compared with the bilateral RT group, but the difference narrowed at 2 years. The major salivary gland flow rates had only a weak correlation with the xerostomia scores. Factors found to be independently associated with the xerostomia scores were the pre-RT baseline scores, the time since RT, and the mean doses to the major salivary glands (notably to the submandibular glands) and to the oral cavity.

CONCLUSION

An improvement over time in xerostomia, occurring in tandem with rising salivary production from the spared major salivary glands, suggests a long-term clinical benefit from their sparing. The oral cavity mean dose, representing RT effect on the minor salivary glands, was found to be a significant, independent predictor of xerostomia. Thus, in addition to the major salivary glands, sparing the uninvolved oral cavity should be considered as a planning objective to further reduce xerostomia.

Salivary scintigraphy for assessing the protective effect of pilocarpine in head and neck irradiated tumours

Patients with head and neck cancers can develop salivary hypofunction after radiotherapy. The use of pilocarpine during radiotherapy treatment has been shown to be an effective treatment, although its usefulness is being discussed. The aim of this study was: (1) to determine the value of a semiquantitative scintigraphy method for measuring the uptake and excretory salivary function of patients with head and neck irradiated tumours; and (2) to study the usefulness of pilocarpine as a salivary gland protector during radiotherapy. We prospectively studied 49 patients (mean age 61 years, range 29-87 years) with head and neck cancer in need of radiotherapy. Patients were divided into two groups consecutively: group P (26 patients) received 5 mg of pilocarpine three times per day starting the day before radiation therapy, and group NP (23 patients) received radiotherapy without pilocarpine and were used as the control group. Salivary gland scintigraphy and a visual analogue scale (VAS) of mouth dryness were obtained from each patient before radiotherapy and during the first year after treatment. The most frequent finding after radiotherapy was a quick impairment in parotid and submaxillary excretion (P < 0.001). There were no statistical differences comparing the pilocarpine group against the non-pilocarpine group. Parotid and submaxillary uptake significantly decreased after radiotherapy in both groups (P < 0.001). However, a tendency to recover within the pilocarpine group was observed in both the parotids and the submaxillary glands at 12 months. No differences were found comparing the VAS results in both groups. Strikingly, VAS data did not correlate with salivary gland dysfunction observed by means of scintigraphy. In conclusion, salivary scintigraphy is a useful technique to evaluate objectively the salivary gland function of patients with head and neck irradiated tumours as well as to test the response to pilocarpine. However, despite better results on the salivary uptake at 12 months, pilocarpine did not significantly improve salivary gland function.