Parotid glands have a dysregulated immune response following radiation therapy.

Head and neck cancer treatment often consists of surgical resection of the tumor followed by ionizing radiation (IR), which can damage surrounding tissues and cause adverse side effects. The underlying mechanisms of radiation-induced salivary gland dysfunction are not fully understood, and treatment options are scarce and ineffective. The wound healing process is a necessary response to tissue injury, and broadly consists of inflammatory, proliferative, and redifferentiation phases with immune cells playing key roles in all three phases. In this study, select immune cells were phenotyped and quantified, and certain cytokine and chemokine concentrations were measured in mouse parotid glands after IR. Further, we used a model where glandular function is restored to assess the immune phenotype in a regenerative response. These data suggest that irradiated parotid tissue does not progress through a typical inflammatory response observed in wounds that heal. Specifically, total immune cells (CD45+) decrease at days 2 and 5 following IR, macrophages (F4/80+CD11b+) decrease at day 2 and 5 and increase at day 30, while neutrophils (Ly6G+CD11b+) significantly increase at day 30 following IR. Additionally, radiation treatment reduces CD3- cells at all time points, significantly increases CD3+/CD4+CD8+ double positive cells, and significantly reduces CD3+/CD4-CD8- double negative cells at day 30 after IR. Previous data indicate that post-IR treatment with IGF-1 restores salivary gland function at day 30, and IGF-1 injections attenuate the increase in macrophages, neutrophils, and CD4+CD8+ T cells observed at day 30 following IR. Taken together, these data indicate that parotid salivary tissue exhibits a dysregulated immune response following radiation treatment which may contribute to chronic loss of function phenotype in head and neck cancer survivors.

Evaluation of photobiomodulation therapy (PBMT) on salivary flow and composition in head and neck cancer patients undergoing radiation therapy.

OBJECTIVE: Assess the impact of photobiomodulation therapy (PBMT) on xerostomia, salivary flow rate (SFR) and composition in patients undergoing radiotherapy (RT) for head and neck cancer (HNC). STUDY DESIGN: Thirty patients undergoing RT (65 Gy) for HNC were enrolled. Saliva and xerostomia evaluations collected pre- and post-PBMT-RT. PBMT involved irradiation of extra and intraoral points, 15-20 sessions, 2-3 times/week. SFR, trace elements, total protein, alkaline phosphatase, xerostomia, and pH were analyzed. RESULTS: The average age was 60.7 years. After treatment, there was not a significant reduction in SFR and there was no difference on xerostomia. Significant reductions in Al, Cd, Fe, Ni, P, and Sb concentrations were observed, along with a significant increase in Mg concentration. Sample data were organized into 3 groups based on a self-organizing map. Low concentrations of Al, As, Co, Cr, Cu, Fe, Mn, Mo, S, Sr, and Zn were the primary discriminatory factors for group A, while group B consisted of post-PBMT-RT samples with high concentrations of Ca, K, Mg, Na, and S. CONCLUSIONS: PBMT prevented a significant reduction in SFR and xerostomia induced by radiation therapy. These findings suggest that PBMT prevents salivary gland damage minimizing the decline in salivary flow.

Metabolomics analysis of pathways underlying radiation-induced salivary gland dysfunction stages.

Salivary gland hypofunction is an adverse side effect associated with radiotherapy for head and neck cancer patients. This study delineated metabolic changes at acute, intermediate, and chronic radiation damage response stages in mouse salivary glands following a single 5 Gy dose. Ultra-high performance liquid chromatography-mass spectrometry was performed on parotid salivary gland tissue collected at 3, 14, and 30 days following radiation (IR). Pathway enrichment analysis, network analysis based on metabolite structural similarity, and network analysis based on metabolite abundance correlations were used to incorporate both metabolite levels and structural annotation. The greatest number of enriched pathways are observed at 3 days and the lowest at 30 days following radiation. Amino acid metabolism pathways, glutathione metabolism, and central carbon metabolism in cancer are enriched at all radiation time points across different analytical methods. This study suggests that glutathione and central carbon metabolism in cancer may be important pathways in the unresolved effect of radiation treatment.

Prediction of Radiation-Induced Parotid Gland-Related Xerostomia in Patients With Head and Neck Cancer: Regeneration-Weighted Dose.

PURPOSE: Despite improvements to treatment, patients with head and neck cancer (HNC) still experience radiation-induced xerostomia due to salivary gland damage. The stem cells of the parotid gland (PG), concentrated in the gland's main ducts (stem cell rich [SCR] region), play a critical role in the PG's response to radiation. Treatment optimization requires a dose metric that properly accounts for the relative contributions of dose to this SCR region and the PG's remainder (non-SCR region) to the risk of xerostomia in normal tissue complication probability (NTCP) models for xerostomia. MATERIALS AND METHODS: Treatment and toxicity data of 1013 prospectively followed patients with HNC treated with definitive radiation therapy (RT) were used. The regeneration-weighted dose, enabling accounting for the hypothesized different effects of dose to the SCR and non-SCR region on the risk of xerostomia, was defined as Dreg PG = Dmean SCR region + r × Dmean non-SCR region, where Dreg is the regeneration-weighted dose, Dmean is the mean dose, and r is the weighting factor. Considering the different volumes of these regions, r > 3.6 in Dreg PG demonstrates an enhanced effect of the SCR region. The most predictive value of r was estimated in 102 patients of a previously published trial testing stem cell sparing RT. For each endpoint, Dreg PG, dose to other organs, and clinical factors were used to develop NTCP models using multivariable logistic regression analysis in 663 patients. The models were validated in 350 patients. RESULTS: Dose to the contralateral PG was associated with daytime, eating-related, and physician-rated grade ≥2 xerostomia. Consequently, r was estimated and found to be smaller than 3.6 for most PG function-related endpoints. Therefore, the contribution of Dmean SCR region to the risk of xerostomia was larger than predicted by Dmean PG. Other frequently selected predictors were pretreatment xerostomia and Dmean oral cavity. The validation showed good discrimination and calibration. CONCLUSIONS: Tools for clinical implementation of stem cell sparing RT were developed: regeneration-weighted dose to the parotid gland that accounted for regional differences in radiosensitivity within the gland and NTCP models that included this new dose metric and other prognostic factors.

Sub-regional analysis of the parotid glands: model development for predicting late xerostomia with radiomics features in head and neck cancer patients.

BACKGROUND: The irradiation of sub-regions of the parotid has been linked to xerostomia development in patients with head and neck cancer (HNC). In this study, we compared the xerostomia classification performance of radiomics features calculated on clinically relevant and de novo sub-regions of the parotid glands of HNC patients. MATERIAL AND METHODS: All patients (N = 117) were treated with TomoTherapy in 30-35 fractions of 2-2.167 Gy per fraction with daily mega-voltage-CT (MVCT) acquisition for image-guidance purposes. Radiomics features (N = 123) were extracted from daily MVCTs for the whole parotid gland and nine sub-regions. The changes in feature values after each complete week of treatment were considered as predictors of xerostomia (CTCAEv4.03, grade ≥ 2) at 6 and 12 months. Combinations of predictors were generated following the removal of statistically redundant information and stepwise selection. The classification performance of the logistic regression models was evaluated on train and test sets of patients using the Area Under the Curve (AUC) associated with the different sub-regions at each week of treatment and benchmarked with the performance of models solely using dose and toxicity at baseline. RESULTS: In this study, radiomics-based models predicted xerostomia better than standard clinical predictors. Models combining dose to the parotid and xerostomia scores at baseline yielded an AUCtest of 0.63 and 0.61 for xerostomia prediction at 6 and 12 months after radiotherapy while models based on radiomics features extracted from the whole parotid yielded a maximum AUCtest of 0.67 and 0.75, respectively. Overall, across sub-regions, maximum AUCtest was 0.76 and 0.80 for xerostomia prediction at 6 and 12 months. Within the first two weeks of treatment, the cranial part of the parotid systematically yielded the highest AUCtest. CONCLUSION: Our results indicate that variations of radiomics features calculated on sub-regions of the parotid glands can lead to earlier and improved prediction of xerostomia in HNC patients.

Research Value of Intensity Modulated Radiation Therapy in Alleviating Parotid Gland Function Injury in Patients with Stage N0 Nasopharyngeal Carcinoma from Physical and Dosimetric Aspects.

Objective: To study the feasibility of intensity modulated radiation therapy (IMRT) for stage N0 nasopharyngeal carcinoma (NPC) and its parotid gland (PG) function preservation from physical and dosimetric aspects. Methods: All the clinical data of 77 patients with pathologically confirmed T1-4N0M0 NPC who received radiotherapy between July 2017 and October 2019 in the Radiotherapy Center of Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University were analyzed retrospectively. Three-dimensional conformal radiotherapy (3D-CRT) and IMRT were used in 35 and 42 cases, respectively. The treatment efficiency and the dosimetry differences of the PG in the intensity modulation plan were compared between groups. Quantitative monitoring of 99mTc radionuclide imaging of PG was performed before, at the end of, and 3, 6, and 12 months after radiotherapy. The degree of PG function injury and xerostomia was compared between groups at the end of radiotherapy and 12 months later. Results: Higher minimal, maximal, and average irradiation doses of PG were determined in 3D-CRT-treated patients compared with IMRT-treated cases (P < 0.05). Compared with before radiotherapy, the PG uptake index (UI) and excretion index (EI) of both cohorts of patients decreased to varying degrees at the end of radiotherapy, with PG function injury and xerostomia symptoms observed in all cases but with no obvious difference between groups (P > 0.05). To a certain extent, the PG function recovered and the xerostomia symptoms relieved in both groups 12 months after radiotherapy, with better improvements in IMRT group versus 3D-CRT group. Conclusion: IMRT has similar short-term efficacy to 3D-CRT in treating patients with stage N0 NPC, but it can effectively reduce the dose of PG radiotherapy and protect the PG function on the premise of ensuring sufficient tumor coverage and dose, showing certain dosimetry advantages.

Cluster model incorporating heterogeneous dose distribution of partial parotid irradiation for radiotherapy induced xerostomia prediction with machine learning methods.

PURPOSE: A cluster model incorporating heterogeneous dose distribution within the parotid gland was developed and validated retrospectively for radiotherapy (RT) induced xerostomia prediction with machine learning (ML) techniques. METHODS: Sixty clusters were obtained at 1 Gy step size with threshold doses ranging from 1 to 60 Gy, for each of the enrolled 155 patients with HNC from three institutions. Feature clusters were selected with the neighborhood component analysis (NCA) and subsequently fed into four supervised ML models for xerostomia prediction comparison: support vector machines (SVM), k-nearest neighbor (kNN), naïve Bayes (NB), and random forest (RF). The predictive performance of each model was evaluated using cross validation resampling with the area-under-the-curves (AUC) of the receiver-operating-characteristic (ROC). The xerostomia predicting capacity using testing data was assessed with accuracy, sensitivity, and specificity for these models and three cluster connectivity choices. Mean dose based logistic regression served as the benchmark for evaluation. RESULTS: Feature clusters identified by NCA fell in three threshold dose ranges: 5-15Gy, 25-35Gy, and 45-50Gy. Mean dose predictive power was 15% lower than that of the cluster model using the logistic regression classifier. Model validation demonstrated that kNN model outperformed slightly other three models but no substantial difference was observed. Applying the fine-tuned models to testing data yielded that the mean accuracy from SVM, kNN and NB models were between 0.68 and 0.7 while that of RF was ∼0.6. SVM model yielded the best sensitivity (0.76) and kNN model delivered consistent sensitivity and specificity. This is consistent with cross validation. Clusters calculated with three connectivity choices exhibited minimally different predictions. CONCLUSION: Compared to mean dose, the proposed cluster model has shown its improvement as the xerostomia predictor. When combining with ML techniques, it could provide a clinically useful tool for xerostomia prediction and facilitate decision making during radiotherapy planning for patients with HNC.

Comparison of effects of dexmedetomidine and amifostine against X-ray radiation-induced parotid damage.

Radiotherapy can be employed as a therapeutic modality alone in the early stages of cancer and is used together with other treatments such as surgery and chemotherapy in more advanced stages. However, exposure to ionizing radiation in association with radiotherapy affects several organs in the head and neck and can give rise to early and late side effects. Exposure to ionizing radiation used in radiotherapy is known to cause cell damage by leading to oxygen stress through the production of free oxygen radicals (such as superoxide radicals, hydroxyl radical, hydrogen peroxide, and singlet oxygen), depending on the total radiation dosage, the fractionation rate, radiosensitivity, and linear energy transfer. The purpose of the present study was to determine the potential protective role of a powerful and highly selective α2-adrenoreceptor agonist with a broad pharmacological spectrum against salivary gland damage induced by ionizing radiation exposure. Forty Sprague-Dawley rats were divided into five groups-control, ionizing radiation, ionizing radiation + dexmedetomidine (100 µg/kg), ionizing radiation + dexmedetomidine (200 µg/kg), and ionizing radiation + amifostine (200 mg/kg). Following exposure to ionizing radiation, we observed necrosis, fibrosis, and vascular congestions in parotid gland epithelial cells. We also observed increases in malondialdehyde (MDA) and cleaved Caspase-3 levels and a decrease in glutathione (GSH). In groups receiving dexmedetomidine, we observed necrotic epithelial cells, fibrosis and vascular congestion in parotid gland tissue, a decrease in MDA levels, and an increase in GSH. Dexmedetomidine may be a promising antioxidant agent for the prevention of oxidative damage following radiation exposure.

Mathematical evaluation of post-radiotherapy salivary gland function using salivary gland scintigraphy.

OBJECTIVE: Xerostomia is the most common treatment-related toxicity after radiotherapy (RT) for head and neck carcinoma, reducing the quality of life of patients due to a decrease in salivary gland function. METHODS: Salivary gland scintigraphy was performed to quantitatively evaluate the salivary gland functions in patients undergoing RT. It was done chronologically for 62 salivary glands of 31 patients before RT and retested 12 months later. RESULTS: The salivary gland functions of most patients deteriorated post-RT and recovered when the radiation dose to the salivary gland was not high. The mean dose to the salivary gland was found to be the most reliable factor in deteriorating salivary gland function, and the tolerance dose was determined to be 46 Gy. The recovery rate of salivary gland function after 1 year of RT was 72% in the RT alone group (n = 10), 56% in the conformal radiotherapy group (n = 15), and 44% in the bioradiotherapy group (n = 6). CONCLUSION: Scintigraphy revealed that the salivary glands recovered from post-RT hypofunction when decreased doses were administered. The determined tolerance dose of 46 Gy may guide the approach to minimizing associated xerostomia in RT. ADVANCES IN KNOWLEDGE: In this study, the average tolerated dose to the salivary glands was 46 Gy.

A nomogram based on clinical information, conventional ultrasound and radiomics improves prediction of malignant parotid gland lesions.

Although conventional ultrasound (CUS) allows for clear detection of parotid gland lesions (PGLs), it fails to accurately provide benign-malignant differentiation due to overlapping morphological features. Radiomics is capable of processing large-quantity volume of data hidden in CUS image undiscovered by naked eyes. The aim was to explore the potential of CUS-based radiomics score (Rad-score) in distinguishing benign (BPGLs) and malignant PGLs (MPGLs). A consecutive of 281 PGLs (197 in training set and 84 in test set) with definite pathological confirmation was retrospectively enrolled. 1465 radiomics features were extracted from CUS images and Rad-score was constructed by using Least Absolute Shrinkage and Selection Operator (LASSO) algorithm. Different nomogram models, including clinic-radiomics (Clin + Rad-score), CUS-clinic (CUS + Clin) and combined CUS-clinic-radiomics (CUS + Clin + Rad-score), were built using logistic regression. The diagnostic performance of different models were calculated and compared by area under receiver operating curve (AUC) and corresponding sensitivity and specificity. Finally, 26 radiomics features were independent signatures for predicting MPGLs, with MPGLs having higher Rad-scores in both cohorts (both P < 0.05). In the test population, CUS + Clin + Rad-score obtained an excellent diagnostic result, with significantly higher AUC value (AUC = 0.91) when compared to that of CUS + Clin (AUC = 0.84) and Clin + Rad-score (AUC = 0.74), respectively (both P < 0.05). In addition, the sensitivity of this combined model was higher than that of single Rad-score model (100.00% vs. 71.43%, P = 0.031) without compromising the specificity value (82.86% vs. 88.57%, P = 0.334). The calibration curve and decision curve analysis also indicated the clinical effectiveness of the proposed combined nomogram. The combined CUS-clinic-radiomics model may help improve the discrimination of BPGLs from MPGLs.

Clinical Use of A Priori Knowledge of Organ-At-Risk Sparing During Radiation Therapy Treatment for Oropharyngeal Cancer: Dosimetric and Patient Reported Outcome Improvements.

PURPOSE: This study aimed to prospectively assess dosimetric and clinical effects of treatment planners having a priori knowledge of the maximum achievable dose sparing for organs at risk (OARs) for patients with oropharynx cancer receiving intensity modulated radiation therapy (RT). METHODS AND MATERIALS: We examined patients with oropharynx cancer who were treated in prospective clinical trials between February 2012 and April 2019 at our institution. A tool generating estimates of maximum achievable dose sparing for OARs (feasibility dose-volume histogram [FDVH]) was used clinically starting July 2016. Patients were divided into 2 cohorts: Before (ie, baseline) and after (ie, FDVH-guided) FDVH. Doses received by various OARs were compared with those estimated to be achievable per FDVH, and that difference was defined as the excess of feasible dose (EFD). Patient-reported outcome (PRO) questionnaires were completed at 3, 6, and 12 months after treatment. The baseline and FDVH-guided cohorts were compared in terms of EFD, plan quality metrics, and post-RT PRO assessments. RESULTS: A total of 139 patients were included in the analysis (60 in the baseline cohort, 79 in the FDVH-guided cohort). The FDVH-guided cohort had lower EFD to the contralateral parotid by 4.1 Gy, the ipsilateral parotid by 10.6 Gy, the larynx by 4.3 Gy, the oral cavity by 1.5 Gy, and the contralateral submandibular gland by 0.4 Gy. Plan quality metrics were similar between the cohorts. Less variation of EFD was seen in the FDVH-guided cohort for the parotid glands and contralateral submandibular gland (P < .05). The average post-RT PROs were better in the FVHD cohort versus baseline (particularly at the 6-month timepoint for dry mouth frequency, sticky saliva, meal enjoyment, severity of pain, and Eating Assessment Tool 10 composite [swallowing]; P < .05). CONCLUSIONS: Use of FDVH was associated with improved and less variable OAR sparing for clinically delivered plans. FDVH-guided patients had improved PROs compared with baseline with a variety of outcomes significantly improved at 6 months after treatment.

Dietary nitrate supplementation prevents radiotherapy-induced xerostomia.

Management of salivary gland hypofunction caused by irradiation (IR) therapy for head and neck cancer remains lack of effective treatments. Salivary glands, especially the parotid gland, actively uptake dietary nitrate and secrete it into saliva. Here, we investigated the effect of dietary nitrate on the prevention and treatment of IR-induced parotid gland hypofunction in miniature pigs, and elucidated the underlying mechanism in human parotid gland cells. We found that nitrate administration prevented IR-induced parotid gland damage in a dose-dependent manner, by maintaining the function of irradiated parotid gland tissue. Nitrate could increase sialin expression, a nitrate transporter expressed in the parotid gland, making the nitrate-sialin feedback loop that facilitates nitrate influx into cells for maintaining cell proliferation and inhibiting apoptosis. Furthermore, nitrate enhanced cell proliferation via the epidermal growth factor receptor (EGFR)-protein kinase B (AKT)-mitogen-activated protein kinase (MAPK) signaling pathway in irradiated parotid gland tissue. Collectively, nitrate effectively prevented IR-induced xerostomia via the EGFR-AKT-MAPK signaling pathway. Dietary nitrate supplementation may provide a novel, safe, and effective way to resolve IR-induced xerostomia.

Head and neck cancers are commonly treated using radiotherapy, where a beam of high-energy radiation is targeted at the tumour. This often severely damages the surrounding salivary glands, leading to chronic dry mouth and impairing a patient's sense of taste, nutrient intake, speech and immune system. Despite this significant impact on quality of life, there is no effective treatment yet for this side effect. In the body, salivary glands are one of the primary users of a compound known as nitrate, which is commonly found in the diet. In the glands, it is ushered into cells thanks to a protein known as sialin. The nutrient supports the activity and maintenance of the glands, before it is released in the saliva. Feng, Wu et al. therefore decided to test whether nitrate could offer protection during neck and head radiotherapy. The experiments used miniature pigs, which have similar salivary glands to humans. The animals that received sodium nitrate before and after exposure to radiation preserved up to 85% of their saliva production. By comparison, without any additional nitrate, saliva production fell to 20% of pre-radiation levels. To understand how this protective effect emerged, Feng, Wu et al. added nitrate to cells from a human salivary gland known as the parotid. This led to the cells producing more sialin, creating a feedback loop which increases the amount of nitrate in the salivary glands. Further examination then showed that the compound promotes growth of cells and reduce their death. These findings therefore suggest that clinical studies may be worthwhile to test if nitrate could be used to prevent dry mouth in head and neck cancer patients who undergo radiotherapy.

A Study to Assess the Dosimetric Impact of the Anatomical Changes Occurring in the Parotid Glands and Tumour Volume during Intensity Modulated Radiotherapy using Simultaneous Integrated Boost (IMRT-SIB) in Head and Neck Squamous Cell Cancers.

BACKGROUND: Anatomical variations in head and neck cancer during IMRT leads to volume shrinkage, results in dosimetric variations in tumour and normal tissue including parotid glands, with a risk of radiation toxicities. METHODS: 30 patients with a stage II-IV head and neck squamous cell carcinoma (HNSCC) were treated with definitive IMRT-SIB and concomitant chemotherapy. Volumetric and dosimetric variations were evaluated during the period of IMRT by recalculating and obtaining dose-volume histograms of re-contoured target volumes and parotid glands on repeat CT scans taken multiple times during treatment (CT1, CT2, CT3 and CT4). RESULTS: Result showed significant (p < 0.001) mean decrease in both primary and nodal tumors volume with time whereas increase (p < 0.01 or p < 0.001) in respective V100 (%) and D2% (Gy). The mean parotid gland dose increased (p < 0.01 or p < 0.001) with time, whereas parotid gland volume and distance between plan isocenter and centre of mass of parotid glands decreased (p < 0.05 or p < 0.001) with time. Patient's mean weight and neck circumference both decrease (p < 0.001) with time whereas ECOG score increase (p < 0.001) with time. The mucosal toxicity increased significantly (p < 0.001) with time. The change in both weight and neck circumference showed significant (p < 0.001) and direct (positive correlation) association with change in parotid gland volume. CONCLUSION: If the PTV and normal anatomy are changing with time, adaptive IMRT would be beneficial radiation dose delivery where possible.

[Impact of neck dissection in N2-3 oropharyngeal squamous cell carcinomas treated with definitive chemoradiotherapy: An observational real-life study]. / Impact du curage ganglionnaire cervical dans la prise en charge par chimioradiothérapie exclusive des cancers de l'oropharynx de stade N2-3 : étude observationnelle en vie réelle.

PURPOSE: The purpose of this study was to assess the efficacy in terms of neck failure of an initial neck dissection before definitive chemoradiotherapy in N2-3 oropharyngeal squamous cell carcinomas, as well as the dosimetric impact and the acute and delayed morbidity of this approach. MATERIALS AND METHODS: All patients consecutively treated between 2009 and 2018 with definitive chemoradiotherapy using intensity-modulated conformal radiotherapy (IMRT) for a histologically proven N2-3 oropharyngeal squamous cell carcinomas were retrospectively included. The therapeutic approach consisted of induction chemotherapy, followed by cisplatine-based chemoradiotherapy preceded or not by neck dissection. Neck dissection was discussed on a case-by-case basis in a dedicated multidisciplinary tumour board for patients with a dissociated response to induction chemotherapy, defined as a better response on the primary than on the node. Chemoradiotherapy without neck dissection was systematically performed in case of a major lymph node response to induction chemotherapy (decrease in size of 90% or more). Intensity-modulated radiotherapy using a simultaneous-integrated boost delivered 70Gy in 35 fractions on macroscopic tumour volumes, 63Gy on intermediate-risk levels or extra-nodal extension and 54Gy on prophylactic lymph node areas. RESULTS: Two groups were constituted: 47 patients without an initial neck dissection (62.7%), and 28 patients with a neck dissection prior to definitive chemoradiotherapy (37.3%). Initial patient characteristics were not statistically different between the two groups. The median follow-up was 60.1months (range: 3.2-119months). Incidence of neck failure was higher in patients without neck dissection (P=0.015). The neck failure rate at 5years was 19.8% (95% confidence interval: 7.4-30.6%; P=0.015) without neck dissection versus 0% following neck dissection. All lymph node failures occurred in the planned target volume at 70Gy. Upfront neck dissection suggested a decrease in the mean dose received by the homolateral parotid gland (P=0.01), mandible (P=0.02), and thyroid gland (P=0.02). Acute toxicity of chemoradiotherapy after neck dissection suggested a reduction in grade≥3 adverse events (P=0.04), early discontinuation of concomitant chemotherapy (P=0.009) and feeding tube-dependence (P=0.008) in univariate analysis. During follow-up, there was no difference between the two groups in terms of xerostomia, dysgeusia, dysphagia or gastrostomy dependence in univariate analysis. CONCLUSION: Neck dissection prior to definitive chemoradiotherapy in N2-3 oropharyngeal squamous cell carcinoma was associated with high neck control without additional mid and long-term morbidity.

Development of a functional salivary gland tissue chip with potential for high-content drug screening.

Radiation therapy for head and neck cancers causes salivary gland dysfunction leading to permanent xerostomia. Limited progress in the discovery of new therapeutic strategies is attributed to the lack of in vitro models that mimic salivary gland function and allow high-throughput drug screening. We address this limitation by combining engineered extracellular matrices with microbubble (MB) array technology to develop functional tissue mimetics for mouse and human salivary glands. We demonstrate that mouse and human salivary tissues encapsulated within matrix metalloproteinase-degradable poly(ethylene glycol) hydrogels formed in MB arrays are viable, express key salivary gland markers, and exhibit polarized localization of functional proteins. The salivary gland mimetics (SGm) respond to calcium signaling agonists and secrete salivary proteins. SGm were then used to evaluate radiosensitivity and mitigation of radiation damage using a radioprotective compound. Altogether, SGm exhibit phenotypic and functional parameters of salivary glands, and provide an enabling technology for high-content/throughput drug testing.

NTCP modeling and dose-volume correlations for acute xerostomia and dry eye after whole brain radiation.

BACKGROUND: Whole brain radiation (WBRT) may lead to acute xerostomia and dry eye from incidental parotid and lacrimal exposure, respectively. We performed a prospective observational study to assess the incidence/severity of this toxicity. We herein perform a secondary analysis relating parotid and lacrimal dosimetric parameters to normal tissue complication probability (NTCP) rates and associated models. METHODS: Patients received WBRT to 25-40 Gy in 10-20 fractions using 3D-conformal radiation therapy without prospective delineation of the parotids or lacrimals. Patients completed questionnaires at baseline and 1 month post-WBRT. Xerostomia was assessed using the University of Michigan xerostomia score (scored 0-100, toxicity defined as ≥ 20 pt increase) and xerostomia bother score (scored from 0 to 3, toxicity defined as ≥ 2 pt increase). Dry eye was assessed using the Subjective Evaluation of Symptom of Dryness (SESoD, scored from 0 to 4, toxicity defined as ≥ 2 pt increase). The clinical data were fitted by the Lyman-Kutcher-Burman (LKB) and Relative Seriality (RS) NTCP models. RESULTS: Of 55 evaluable patients, 19 (35%) had ≥ 20 point increase in xerostomia score, 11 (20%) had ≥ 2 point increase in xerostomia bother score, and 13 (24%) had ≥ 2 point increase in SESoD score. For xerostomia, parotid V10Gy-V20Gy correlated best with toxicity, with AUC 0.68 for xerostomia score and 0.69-0.71 for bother score. The values for the D50, m and n parameters of the LKB model were 22.3 Gy, 0.84 and 1.0 for xerostomia score and 28.4 Gy, 0.55 and 1.0 for bother score, respectively. The corresponding values for the D50, γ and s parameters of the RS model were 23.5 Gy, 0.28 and 0.0001 for xerostomia score and 32.0 Gy, 0.45 and 0.0001 for bother score, respectively. For dry eye, lacrimal V10Gy-V15Gy were found to correlate best with toxicity, with AUC values from 0.67 to 0.68. The parameter values of the LKB model were 53.5 Gy, 0.74 and 1.0, whereas of the RS model were 54.0 Gy, 0.37 and 0.0001, respectively. CONCLUSIONS: Xerostomia was most associated with parotid V10Gy-V20Gy, and dry eye with lacrimal V10Gy-V15Gy. NTCP models were successfully created for both toxicities and may help clinicians refine dosimetric goals and assess levels of risk in patients receiving palliative WBRT.

Parotid sparing and quality of life in long-term survivors of locally advanced head and neck cancer after intensity-modulated radiation therapy.

PURPOSE: Intensity-modulated radiation therapy (IMRT) enables radiation oncologists to optimally spare organs at risk while achieving homogeneous dose distribution in the target volume. Despite great advances in technology, xerostomia is one of the most detrimental long-term side effects after multimodal therapy in patients with locally advanced head and neck cancer (HNC). This prospective observational study examines the effect of parotid sparing on quality of life in long-term survivors. PATIENTS AND METHODS: A total of 138 patients were grouped into unilateral (n = 75) and bilateral (n = 63) parotid sparing IMRT and questioned at 3, 24, and 60-month follow-up using the European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-H&N35 questionnaires. Treatment-related toxicity was scored according to the RTOG/EORTC toxicity criteria. Patients' QoL 24 and 60 months after IMRT was analyzed by ANCOVA using baseline QoL (3 months after IMRT) as a covariate. RESULTS: Patients with bilateral and unilateral parotid-sparing IMRT surviving 60 months experience similar acute and late side effects and similar changes in QoL. Three months after IMRT, physical and emotional function as well as fatigue, nausea and vomiting, pain, dyspnea, and financial problems are below (function scales) or above (symptom scales) the threshold of clinical importance. In both groups, symptom burden (EORTC H&N35) is high independent of parotid sparing 3 months after IMRT and decreases over time in a similar pattern. Pain and financial function remain burdensome throughout. CONCLUSION: Long-term HNC survivors show a similar treatment-related toxicity profile independent of unilateral vs. bilateral parotid-sparing IMRT. Sparing one or both parotids had no effect on global QoL nor on the magnitude of changes in function and symptom scales over the observation period of 60 months. The financial impact of the disease and its detrimental effect on long-term QoL pose an additional risk to unmet needs in this special patient population. These results suggest that long-term survivors need and most likely will benefit from early medical intervention and support within survivorship programs.

Sialographic Analysis of Radioiodine-Associated Chronic Sialadenitis.

OBJECTIVES/HYPOTHESIS: To apply a novel sialography classification system to identify parotid and submandibular ductal findings following I-131 therapy and to assess correlates to dose and duration of symptoms. STUDY DESIGN: Retrospective single-center case series. METHODS: Patients who underwent sialography between February 2008 and February 2019 after previously receiving I-131 treatment were identified via a retrospective chart review. Their sialograms were systematically evaluated and scored by applying the Iowa parotid sialogram scale to also include submandibular gland analysis. RESULTS: From 337 sialograms, 30 (five submandibular, 25 parotid) underwent analysis. Ductal stenosis was identified in all sialograms and was graded as moderate (>50%-75%) in 7/30 cases and severe (>75%) in 15/30 cases. The distal (main) duct was narrowed in 23/30 cases. No association was identified between degree of ductal stenosis and I-131 dose (P = .39), age (P = .81), or time from I-131 therapy to sialogram (P = .97). CONCLUSIONS: The Iowa parotid sialogram scale was successfully applied to report abnormalities of the parotid and submandibular ductal system. The most common manifestation of I-131-associated sialadenitis was a severe stenosis within the distal salivary duct. No statistically significant association was found between degree of ductal stenosis and dose of I-131, age, or duration of symptoms. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E1450-E1456, 2021.

Yap activation in irradiated parotid salivary glands is regulated by ROCK activity.

Radiotherapy plays a major role in the curative treatment of head and neck cancer, either as a single modality therapy, or in combination with surgery or chemotherapy, or both. Despite advances to limit radiation-induced side-effects, the major salivary glands are often affected. This frequently leads to hyposalivation which causes an increased risk for xerostomia, dental caries, mucositis, and malnutrition culminating in a significant impact on patients' quality of life. Previous research demonstrated that loss of salivary function is associated with a decrease in polarity regulators and an increase in nuclear Yap localization in a putative stem and progenitor cell (SPC) population. Yap activation has been shown to be essential for regeneration in intestinal injury models; however, the highest levels of nuclear Yap are observed in irradiated salivary SPCs that do not regenerate the gland. Thus, elucidating the inputs that regulate nuclear Yap localization and determining the role that Yap plays within the entire tissue following radiation damage and during regeneration is critical. In this study, we demonstrate that radiation treatment increases nuclear Yap localization in acinar cells and Yap-regulated genes in parotid salivary tissues. Conversely, administration of insulin-like growth factor 1 (IGF1), known to restore salivary function in mouse models, reduces nuclear Yap localization and Yap transcriptional targets to levels similar to untreated tissues. Activation of Rho-associated protein kinase (ROCK) using calpeptin results in increased Yap-regulated genes in primary acinar cells while inhibition of ROCK activity (Y-27632) leads to decreased Yap transcriptional targets. These results suggest that Yap activity is dependent on ROCK activity and provides new mechanistic insights into the regulation of radiation-induced hyposalivation.

Recommendation regarding the cranial upper border of level IIb in delineating clinical target volumes (CTV) for nasopharyngeal carcinoma.

PURPOSE: To recommend a cranial border for level IIb in delineating clinical target volumes (CTV) for nasopharyngeal carcinoma (NPC) patients receiving intensity-modulated radiotherapy and to help reach a consensus on contouring level IIb in CTV. METHODS: From 2012 to 2016, 331 nonmetastatic NPC patients treated with IMRT were retrospectively enrolled. Based on the AJCC 8th staging system of NPC, there were 15 stage I, 76 stage II, 103 stage III, and 137 stage IV patients. The distribution of cervical lymph nodes in NPC was assessed based on imaging. Comparisons of the safety and parotid dose parameters between patients with and without a reduction in the size of level IIb were conducted using SPSS 25.0 and R 2.14.2 software. RESULTS: Metastasis rates in the most commonly involved lymph nodes, the lateral retropharyngeal and IIb nodes, were 82.8% and 64.0%, respectively. Among patients with level IIb involvement, the upper borders of the metastatic nodes were beyond the caudal edge of C1 in 13.7% of cases. The parotid gland D50 and V26 values were significantly reduced after modifying the upper bound of level IIb used to delineate the CTV (P = 0.000). CONCLUSION: In principle, the upper bound of level IIb should reach the lateral skull base during delineation of the cervical CTV for NPC. To protect the parotid glands, however, individualized reduction of the upper bound of level IIb is recommended for patients who meet certain criteria.