Predictive modelling for swallowing dysfunction after primary (chemo)radiation: results of a prospective observational study

Late-xerostomia prediction model based on 18F-FDG PET image biomarkers of the main salivary glands

BACKGROUND AND PURPOSE

Recently, a comprehensive xerostomia prediction model was published, based on baseline xerostomia, mean dose to parotid glands (PG) and submandibular glands (SMG). Previously, PET imaging biomarkers (IBMs) of PG were shown to improve xerostomia prediction. Therefore, this study aimed to explore the potential improvement of the additional PET-IBMs from both PG and SMG to the recent comprehensive xerostomia prediction model (i.e., the reference model).

MATERIALS AND METHODS

Totally, 540 head and neck cancer patients were split into training and validation cohorts. PET-IBMs from the PG and SMG, were selected using bootstrapped forward selection based on the reference model. The IBMs from both the PG and SMG with the highest selection frequency were added to the reference model, resulting in a PG-IBM model and a SMG-IBM model which were combined into a composite model. Model performance was assessed using the area under the curve (AUC). Likelihood ratio test compared the predictive performance between the reference model and models including IBMs.

RESULTS

The final selected PET-IBMs were 90th percentile of the PG SUV and total energy of the SMG SUV. The additional two PET-IBMs in the composite model improved the predictive performance of the reference model significantly. The AUC of the reference model and the composite model were 0.67 and 0.69 in the training cohort, and 0.71 and 0.73 in the validation cohort, respectively.

CONCLUSION

The composite model including two additional PET-IBMs from PG and SMG improved the predictive performance of the reference xerostomia model significantly, facilitating a more personalized prediction approach.

Dosimetric and NTCP analyses for selecting parotid gland cancer patients for proton therapy

PURPOSE/OBJECTIVE

To perform a dosimetric and a normal tissue complication probability (NTCP) comparison between intensity modulated proton therapy and photon volumetric modulated arc therapy in a cohort of patients with parotid gland cancers in a post-operative or radical setting.

MATERIALS AND METHODS

From May 2011 to September 2021, 37 parotid gland cancers patients treated at two institutions were eligible. Inclusion criteria were as follows: patients aged ⩾ 18 years, diagnosis of parotid gland cancers candidate for postoperative radiotherapy or definitive radiotherapy, presence of written informed consent for the use of anonymous data for research purposes. Organs at risk (OARs) were retrospectively contoured. Target coverage goal was defined as D95 > 98%. Six NTCP models were selected. NTCP profiles were calculated for each patient using an internally-developed Python script in RayStation TPS. Average differences in NTCP between photon and proton plans were tested for significance with a two-sided Wilcoxon signed-rank test.

RESULTS

Seventy-four plans were generated. A lower Dmean to the majority of organs at risk (inner ear, cochlea, oral cavity, pharyngeal constrictor muscles, contralateral parotid and submandibular gland) was obtained with intensity modulated proton therapy vs volumetric modulated arc therapy with statistical significance (p < .05). Ten (27%) patients had a difference in NTCP (photon vs proton plans) greater than 10% for hearing loss and tinnitus: among them, seven qualified for both endpoints, two patients for hearing loss only, and one for tinnitus.

CONCLUSIONS

In the current study, nearly one-third of patients resulted eligible for proton therapy and they were the most likely to benefit in terms of prevention of hearing loss and tinnitus.

Machine learning in the evaluation of voice and swallowing in the head and neck cancer patient

PURPOSE OF REVIEW

The purpose of this review is to present recent advances and limitations in machine learning applied to the evaluation of speech, voice, and swallowing in head and neck cancer.

RECENT FINDINGS

Novel machine learning models incorporating diverse data modalities with improved discriminatory capabilities have been developed for predicting toxicities following head and neck cancer therapy, including dysphagia, dysphonia, xerostomia, and weight loss as well as guiding treatment planning. Machine learning has been applied to the care of posttreatment voice and swallowing dysfunction by offering objective and standardized assessments and aiding innovative technologies for functional restoration. Voice and speech are also being utilized in machine learning algorithms to screen laryngeal cancer.

SUMMARY

Machine learning has the potential to help optimize, assess, predict, and rehabilitate voice and swallowing function in head and neck cancer patients as well as aid in cancer screening. However, existing studies are limited by the lack of sufficient external validation and generalizability, insufficient transparency and reproducibility, and no clear superior predictive modeling strategies. Algorithms and applications will need to be trained on large multiinstitutional data sets, incorporate sociodemographic data to reduce bias, and achieve validation through clinical trials for optimal performance and utility.

Pharyngeal Constrictor Dose-Volume Histogram Metrics and Patient-Reported Dysphagia in Head and Neck Radiotherapy

AIMS

Head and neck radiotherapy long-term survival continues to improve and the management of long-term side-effects is moving to the forefront of patient care. Dysphagia is associated with dose to the pharyngeal constrictors and can be measured using patient-reported outcomes to evaluate its effect on quality of life. The aim of the present study was to relate pharyngeal constrictor dose-volume parameters with patient-reported outcomes to identify prognostic dose constraints.

MATERIALS AND METHODS

A 64-patient training cohort and a 24-patient testing cohort of oropharynx and nasopharynx cancer patients treated with curative-intent chemoradiotherapy were retrospectively examined. These patients completed the MD Anderson Dysphagia Inventory outcome survey at 12 months post-radiotherapy to evaluate late dysphagia: a composite score lower than 60 indicated dysphagia. The pharyngeal constrictor muscles were subdivided into four substructures: superior, middle, inferior and cricopharyngeal. Dose-volume histogram (DVH) metrics for each of the structure combinations were extracted. A decision tree classifier was run for each DVH metric to identify dose constraints optimising the accuracy and sensitivity of the cohort. A 60% accuracy threshold and feature selection method were used to ensure statistically significant DVH metrics were identified. These dose constraints were then validated on the 24-patient testing cohort.

RESULTS

Existing literature dose constraints only had two dose constraints performing above 60% accuracy and sensitivity when evaluated on our training cohort. We identified two well-performing dose constraints: the pharyngeal constrictor muscle D63% < 55 Gy and the superior-middle pharyngeal constrictor combination structure V31Gy < 100%. Both dose constraints resulted in ≥73% mean accuracy and ≥80% mean sensitivity on the training and testing patient cohorts. In addition, a pharyngeal constrictor muscle mean dose <57 Gy resulted in a mean accuracy ≥74% and mean sensitivity ≥60%.

CONCLUSION

Mid-dose pharyngeal constrictor muscle and substructure combination dose constraints should be used in the treatment planning process to reduce late patient-reported dysphagia.

Essentially unedited deep-learning-based OARs are suitable for rigorous oropharyngeal and laryngeal cancer treatment planning

Quality of organ at risk (OAR) autosegmentation is often judged by concordance metrics against the human-generated gold standard. However, the ultimate goal is the ability to use unedited autosegmented OARs in treatment planning, while maintaining the plan quality. We tested this approach with head and neck (HN) OARs generated by a prototype deep-learning (DL) model on patients previously treated for oropharyngeal and laryngeal cancer. Forty patients were selected, with all structures delineated by an experienced physician. For each patient, a set of 13 OARs were generated by the DL model. Each patient was re-planned based on original targets and unedited DL-produced OARs. The new dose distributions were then applied back to the manually delineated structures. The target coverage was evaluated with inhomogeneity index (II) and the relative volume of regret. For the OARs, Dice similarity coefficient (DSC) of areas under the DVH curves, individual DVH objectives, and composite continuous plan quality metric (PQM) were compared. The nearly identical primary target coverage for the original and re-generated plans was achieved, with the same II and relative volume of regret values. The average DSC of the areas under the corresponding pairs of DVH curves was 0.97 ± 0.06. The number of critical DVH points which met the clinical objectives with the dose optimized on autosegmented structures but failed when evaluated on the manual ones was 5 of 896 (0.6%). The average OAR PQM score with the re-planned dose distributions was essentially the same when evaluated either on the autosegmented or manual OARs. Thus, rigorous HN treatment planning is possible with OARs segmented by a prototype DL algorithm with minimal, if any, manual editing.

Cone beam CT-based adaptive intensity modulated proton therapy assessment using automated planning for head-and-neck cancer

BACKGROUND

To assess the feasibility of CBCT-based adaptive intensity modulated proton therapy (IMPT) using automated planning for treatment of head and neck (HN) cancers.

METHODS

Twenty HN cancer patients who received radiotherapy and had pretreatment CBCTs were included in this study. Initial IMPT plans were created using automated planning software for all patients. Synthetic CTs (sCT) were then created by deforming the planning CT (pCT) to the pretreatment CBCTs. To assess dose calculation accuracy on sCTs, repeat CTs (rCTs) were deformed to the pretreatment CBCT obtained on the same day to create deformed rCT (rCTdef), serving as gold standard. The dose recalculated on sCT and on rCTdef were compared by using Gamma analysis. The accuracy of DIR generated contours was also assessed. To explore the potential benefits of adaptive IMPT, two sets of plans were created for each patient, a non-adapted IMPT plan and an adapted IMPT plan calculated on weekly sCT images. The weekly doses for non-adaptive and adaptive IMPT plans were accumulated on the pCT, and the accumulated dosimetric parameters of two sets were compared.

RESULTS

Gamma analysis of the dose recalculated on sCT and rCTdef resulted in a passing rate of 97.9% ± 1.7% using 3 mm/3% criteria. With the physician-corrected contours on the sCT, the dose deviation range of using sCT to estimate mean dose for the most organ at risk (OARs) can be reduced to (- 2.37%, 2.19%) as compared to rCTdef, while for V95 of primary or secondary CTVs, the deviation can be controlled within (- 1.09%, 0.29%). Comparison of the accumulated doses from the adaptive planning against the non-adaptive plans reduced mean dose to constrictors (- 1.42 Gy ± 2.79 Gy) and larynx (- 2.58 Gy ± 3.09 Gy). The reductions result in statistically significant reductions in the normal tissue complication probability (NTCP) of larynx edema by 7.52% ± 13.59%. 4.5% of primary CTVs, 4.1% of secondary CTVs, and 26.8% tertiary CTVs didn't meet the V95 > 95% constraint on non-adapted IMPT plans. All adaptive plans were able to meet the coverage constraint.

CONCLUSION

sCTs can be a useful tool for accurate proton dose calculation. Adaptive IMPT resulted in better CTV coverage, OAR sparing and lower NTCP for some OARs as compared with non-adaptive IMPT.

Frailty is an independent factor for health-related quality of life in patients with head and neck cancer receiving definitive concurrent chemoradiotherapy

PURPOSE

Health-related quality of life (HRQoL) is associated with treatment-related complications and poor survival in patients with head and neck cancer (HNC). We investigated the effects of frailty on HRQoL in patients with HNC receiving definitive concurrent chemoradiotherapy (CCRT).

METHODS

A total of 461 consecutive patients with locally advanced HNC who received CCRT between 2017 and 2018 at three medical centers in Taiwan were included. Frailty and HRQoL were assessed using the Comprehensive Geriatric Assessment and QLQ-H&N35 before CCRT. The sum score was calculated based on the first 30 questions of QLQ-H&N35. Multivariate analysis was performed to evaluate the impact of frailty on HRQoL.

RESULTS

The overall sum score was 39 (34-49). The sum scores of patients with impairments in 0, 1, 2, 3, and ≥ 4 frailty domains were 34 (32-38), 40 (34-47), 46 (36-55), 48 (41-64), and 56 (50-60), respectively. Patients with impairments in more frailty domains had a higher symptom burden (p for trend < 0.001). Frail patients tended to experience symptoms across all QLQ-H&N35 subscales. Sex, body mass index, tumor type, tumor stage, Eastern Cooperative Oncology Group performance status, and frailty were determinants of HRQoL in the univariate analysis. Frailty was an independent determinant of HRQoL in the multivariate analysis.

CONCLUSION

Routine frailty assessment may serve as a surrogate for the selection of patients with HNC with poor HRQoL before CCRT. Further studies are needed to determine whether appropriate interventions in frail patients would improve their HRQoL during CCRT.

Radiation-induced long-term dysphagia in survivors of head and neck cancer and association with dose-volume parameters

BACKGROUND

Although dysphagia is a common side effect after radiotherapy (RT) of head and neck cancer (HNC), data on long-term dysphagia is scarce. We aimed to 1) compare radiation dose parameters in HNC survivors with and without dysphagia, 2) investigate factors associated with long-term dysphagia and its possible impact on health-related quality of life (HRQoL), and 3) investigate how our data agree with existing NTCP models.

METHODS

This cross-sectional study conducted in 2018-2020, included HNC survivors treated in 2007-2013. Participants attended a one-day examination in hospital and filled in patient questionnaires. Dysphagia was measured with the EORTC QLQ-H&N35 swallowing scale. Toxicity was scored with CTCAE v.4. We contoured swallowing organs at risk (SWOAR) on RT plans, calculated dose-volume histograms (DVHs), performed logistic regression analyses and tested our data in established NTCP models.

RESULTS

Of the 239 participants, 75 (31%) reported dysphagia. Compared to survivors without dysphagia, this group had reduced HRQoL and the DVHs for infrahyoid SWOAR were significantly shifted to the right. Long-term dysphagia was associated with age (OR 1.07, 95% CI 1.03-1.10), female sex (OR 2.75, 95% CI 1.45-5.21), and mean dose to middle pharyngeal constrictor muscle (MD-MPCM) (OR 1.06, 95% CI 1.03-1.09). NTCP models overall underestimated the risk of long-term dysphagia.

CONCLUSIONS

Long-term dysphagia was associated with higher age, being female, and high MD-MPCM. Doses to distally located SWOAR seemed to be risk factors. Existing NTCP models do not sufficiently predict long-term dysphagia. Further efforts are needed to reduce the prevalence and consequences of this late effect.

Considerations for study design in the DAHANCA 35 trial of protons versus photons for head and neck cancer

Proton radiotherapy offers a dosimetric advantage compared to photon therapy in sparing normal tissue, but the clinical evidence for toxicity reductions in the treatment of head and neck cancer is limited. The Danish Head and Neck Cancer Group (DAHANCA) has initiated the DAHANCA 35 randomised trial to clarify the value of proton therapy (NCT04607694). The DAHANCA 35 trial is performed in an enriched population of patients selected by an anticipated benefit of proton therapy to reduce the risk of late dysphagia or xerostomia based on normal tissue complication probability (NTCP) modelling. We present our considerations on the trial design and a test of the selection procedure conducted before initiating the randomised study.

Symptoms of oropharyngeal dysphagia, efficiency, and safety of swallowing in patients after treatment for head and neck cancer

PURPOSE

The aim of this study is to investigate the relation between symptoms and signs of oropharyngeal dysphagia after treatment for head and neck cancer.

METHODS

An observational analytical study with retrospective and prospective components was carried out including 25 adult and elderly patients with head and neck cancer who had completed the treatment at least 3 months before data collection. Data from the Eating Assessment Tool (EAT-10) protocol were analyzed, as well as from the videofluoroscopic swallowing exams. Based on videofluoroscopy, the degree of oropharyngeal dysphagia was classified, as well as the safety and efficiency grade using the DIGEST (Dynamic Imaging Grade of Swallowing Toxicity) scale. Pearson's correlation test was applied, adopting a significance level of 5%.

RESULTS

There was a significant correlation between question 4 of the EAT-10 (swallowing solids takes extra effort) and the efficiency profile (p = 0.004), as well as between question 4 and the DIGEST score (p = 0.002). No significant relation was found between the DIGEST score and EAT-10 total score (p = 0.180) and not even between EAT-10 total score and efficiency (p = 0.129) or safety grade (p = 0.878).

CONCLUSION

In conclusion, no relation was found between most of the dysphagia signs and symptoms investigated, demonstrating that the individual's perception of the swallowing function may not be consistent with the findings of the instrumental evaluation after long-term treatment for head and neck cancer.

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.

Adaptive FDG-PET/CT guided dose escalation in head and neck squamous cell carcinoma: Late toxicity and oncologic outcomes (The ADMIRE study)

Purpose

To report on the late toxicity and local control (LC) of head and neck cancer patients treated with adaptive FDG-PET/CT response-guided radiotherapy (ADMIRE) with dose escalation (NCT03376386).

Materials and methods

Between December 2017 and April 2019, 20 patients with stage II-IV squamous cell carcinoma of the larynx, hypopharynx or oropharynx were treated within the ADMIRE study where FDG-PET/CT response-guided (Week 2&4) dose escalation was applied (total dose 70-78 Gy). Cisplatin or cetuximab was added to radiotherapy in case of T3-4 and/or N2c disease. To compare the LC and late toxicity of the study population, we used an external control group (n = 67) consisting of all eligible patients for the study (but not participated). These patients were treated in our institution during the same period with the current standard of 70 Gy radiotherapy. To reduce the effect of confounding, logistic regression analyses was done using stabilized inverse probability of treatment weighting (SIPTW).

Results

After median follow-up of 40 and 43 months for the ADMIRE and control groups, the 3-year LC-rates were 74% and 78%, respectively (adjusted HR after SIPTW 0.80, 95 %CI 0.25-2.52, p = 0.70). The incidences of any late G3 toxicity were 35% and 18%, respectively. The adjusted OR for any late G3 toxicity was 5.09 (95 %CI 1.64-15.8, p = 0.005), for any late G ≥ 2 toxicity was 3.67 (95 %CI 1.2-11.7, p = 0.02), for persistent laryngeal edema was 10.95 (95% CI 2.71-44.29, p = 0.001), for persistent mucosal ulcers was 4.67 (95% CI 1.23-17.7, p = 0.023), and for late G3 radionecrosis was 15.69 (95 %CI 2.43-101.39, p = 0.004).

Conclusion

Given the comparable LC rates with increased late toxicity in the ADMIRE group, selection criteria for future adaptive dose escalation trials (preferably randomized) need to be refined to include only patients at higher risk of local failure and/or lower risk of severe late toxicity.

Patient selection for proton therapy using Normal Tissue Complication Probability with deep learning dose prediction for oropharyngeal cancer

BACKGROUND

In cancer care, determining the most beneficial treatment technique is a key decision affecting the patient's survival and quality of life. Patient selection for proton therapy (PT) over conventional radiotherapy (XT) currently entails comparing manually generated treatment plans, which requires time and expertise.

PURPOSE

We developed an automatic and fast tool, AI-PROTIPP (Artificial Intelligence Predictive Radiation Oncology Treatment Indication to Photons/Protons), that assesses quantitatively the benefits of each therapeutic option. Our method uses deep learning (DL) models to directly predict the dose distributions for a given patient for both XT and PT. By using models that estimate the Normal Tissue Complication Probability (NTCP), namely the likelihood of side effects to occur for a specific patient, AI-PROTIPP can propose a treatment selection quickly and automatically.

METHODS

A database of 60 patients presenting oropharyngeal cancer, obtained from the Cliniques Universitaires Saint Luc in Belgium, was used in this study. For every patient, a PT plan and an XT plan were generated. The dose distributions were used to train the two dose DL prediction models (one for each modality). The model is based on U-Net architecture, a type of convolutional neural network currently considered as the state of the art for dose prediction models. A NTCP protocol used in the Dutch model-based approach, including grades II and III xerostomia and grades II and III dysphagia, was later applied in order to perform automatic treatment selection for each patient. The networks were trained using a nested cross-validation approach with 11-folds. We set aside three patients in an outer set and each fold consists of 47 patients in training, five in validation and five for testing. This method allowed us to assess our method on 55 patients (five patients per test times the number of folds).

RESULTS

The treatment selection based on the DL-predicted doses reached an accuracy of 87.4% for the threshold parameters set by the Health Council of the Netherlands. The selected treatment is directly linked with these threshold parameters as they express the minimal gain brought by the PT treatment for a patient to be indicated to PT. To validate the performance of AI-PROTIPP in other conditions, we modulated these thresholds, and the accuracy was above 81% for all the considered cases. The difference in average cumulative NTCP per patient of predicted and clinical dose distributions is very similar (less than 1% difference).

CONCLUSIONS

AI-PROTIPP shows that using DL dose prediction in combination with NTCP models to select PT for patients is feasible and can help to save time by avoiding the generation of treatment plans only used for the comparison. Moreover, DL models are transferable, allowing, in the future, experience to be shared with centers that would not have PT planning expertise.

Head and Neck Low Grade Chondrosarcoma-A Rare Entity

Chondrosarcoma represents approximately 0.1% of all neoplasms of the head and neck and is considered a rare disease with a relatively good prognosis. The 5-year overall survival (OS) rate is estimated at 70-80%, being considered a disease with a low growth rate. Approximately 13% of all cases of chondrosarcoma are located in the region of the head and neck. We present the case of a 30-year-old patient without a medical history who reported dysphagia, swallowing difficulty, neck mass sensation and dysphonia that started insidiously after an upper respiratory tract infection. Subsequently, the patient was diagnosed with a low-grade glosso-epiglottic region chondrosarcoma and was multimodally treated with surgery followed by chemotherapy and radiotherapy. The radiation treatment was delivered with a Rokus M40 former Soviet Union cobalt machine without any image guidance capabilities. The inability to obtain resection margin information justified an aggressive adjuvant treatment with chemotherapy and radiotherapy. The early loss from the oncological record without recurrence of the disease could be associated in this case with the consequence of a major complication, of which we could assume an aspiration pneumonia secondary to a dysphagia associated with an aggressive multidisciplinary treatment. Large tumor size and positive resection margins (R1 resection) are risk factors that support an intensive adjuvant approach in order to reduce the risk of recurrence, but the low grade of tumor associated with a lower risk of recurrence as well as the adverse events (AE) of adjuvant radiotherapy and chemotherapy justify a more reserved therapeutic approach. Taking into account the longer life expectancy of these patients, it is recommended to use a more conformal irradiation technique in order to reduce doses to radiosensitive structures as well as to omit elective neck irradiation, taking into account the lower risk of lymph node involvement. The lack of guidelines, which include very rare tumors including low grade chondrosarcoma of the head and neck, makes a unified approach difficult, but the data presented in case reports could contribute to choosing the regimen that offers the best therapeutic ratio.

Development and Evaluation of the Psychometric Properties of the Tamil Version of Eating Assessment Tool - 10 (EAT-10): Preliminary Findings from Persons with Head and Neck Cancer

Aims: This study aimed to develop and evaluate the psychometric properties of the Tamil version of the Eating Assessment Tool (EAT-10). Setting & Study Design: Prospective cross-sectional study on persons with Head and Neck Cancer (HNC) during their follow-up for oncological and swallowing consultation at a tertiary care hospital and healthy individuals recruited from the community. Methods: The study was conducted in two phases: (1) translation and development of the Tamil version of EAT-10 and (2) administration of Tamil EAT-10 to assess internal consistency reliability, test-retest reliability and known-group validity. 92 participants with HNC in the clinical group and 149 healthy adults in the control group completed the Tamil EAT-10. In addition, a subgroup of 20 participants with HNC repeated the questionnaire within a week to assess test-retest reliability. Results: The Cronbach alpha for the 10 items was 0.96 indicating high internal consistency reliability. The test-retest reliability of the individual items and the total scores (r = 0.98) of the Tamil version of EAT-10 were high. The total EAT-10 scores for the HNC group (14.4 ± 11.5) were significantly higher (p < 0.001) than the scores for healthy adults (0.72 ± 2.0). Conclusion: The Tamil version of the EAT-10 developed in this study is a reliable and valid self-administered tool for identifying concerns related to swallowing among persons treated for HNC and healthy adults. This tool can be implemented for clinical practice and research in dysphagia among a Tamil-speaking population.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-022-03376-8.

Evaluating the effect of setup uncertainty reduction and adaptation to geometric changes on normal tissue complication probability using online adaptive head and neck intensity modulated proton therapy

Objective. To evaluate the impact of setup uncertainty reduction (SUR) and adaptation to geometrical changes (AGC) on normal tissue complication probability (NTCP) when using online adaptive head and neck intensity modulated proton therapy (IMPT).Approach.A cohort of ten retrospective head and neck cancer patients with daily scatter corrected cone-beam CT (CBCT) was studied. For each patient, two IMPT treatment plans were created: one with a 3 mm setup uncertainty robustness setting and one with no explicit setup robustness. Both plans were recalculated on the daily CBCT considering three scenarios: the robust plan without adaptation, the non-robust plan without adaptation and the non-robust plan with daily online adaptation. Online-adaptation was simulated using an in-house developed workflow based on GPU-accelerated Monte Carlo dose calculation and partial spot-intensity re-optimization. Dose distributions associated with each scenario were accumulated on the planning CT, where NTCP models for six toxicities were applied. NTCP values from each scenario were intercompared to quantify the reduction in toxicity risk induced by SUR alone, AGC alone and SUR and AGC combined. Finally, a decision tree was implemented to assess the clinical significance of the toxicity reduction associated with each mechanism.Main results. For most patients, clinically meaningful NTCP reductions were only achieved when SUR and AGC were performed together. In these conditions, total reductions in NTCP of up to 30.48 pp were obtained, with noticeable NTCP reductions for aspiration, dysphagia and xerostomia (mean reductions of 8.25, 5.42 and 5.12 pp respectively). While SUR had a generally larger impact than AGC on NTCP reductions, SUR alone did not induce clinically meaningful toxicity reductions in any patient, compared to only one for AGC alone.SignificanceOnline adaptive head and neck proton therapy can only yield clinically significant reductions in the risk of long-term side effects when combining the benefits of SUR and AGC.

Clinical outcome after pencil beam scanning proton therapy and dysphagia/xerostomia NTCP calculations of proton and photon radiotherapy delivered to patients with cancer of the major salivary glands

OBJECTIVES

The purpose of this study is to report the oncological outcome, observed toxicities and normal tissue complication probability (NTCP) calculation for pencil beam scanning (PBS) PT delivered to salivary gland tumour (SGT) patients.

METHODS

We retrospectively reviewed 26 SGT patients treated with PBSPT (median dose, 67.5 Gy(RBE)) between 2005 and 2020 at our institute. Toxicities were recorded according to CTCAEv.4.1. Overall survival (OS), local control (LC), locoregional control (LRC) and distant control (DC) were estimated. For all patients, a photon plan was re-calculated in order to assess the photon/proton NTCP.

RESULTS

With a median follow-up time of 46 months (range, 3-118), 5 (19%), 2 (8%), 3 (12%) and 2 (8%) patients presented after PT with distant, local, locoregional failures and death, respectively. The estimated 4 year OS, LC, LCR and DC were 90%, 90%, 87 and 77%, respectively. Grade 3 late toxicity was observed in 2 (8%) patients. The estimated 4 year late high-grade (≥3) toxicity-free survival was 78.4%. The calculated mean difference of NTCP-values after PBSPT and VMAT plans for developing Grade 2 or 3 xerostomia were 3.8 and 2.9%, respectively. For Grade 2-3 dysphagia, the grade corresponding percentages were 8.6 and 1.9%. Not using an up-front model-based approach to select patients for PT, only 40% of our patients met the Dutch eligibility criteria.

CONCLUSION

Our data suggest excellent oncological outcome and low late toxicity rates for patients with SGT treated with PBSPT. NTCP calculation showed a substantial risk reduction for Grade 2 or 3 xerostomia and dysphagia in some SGT patients, while for others, no clear benefit was seen with protons, suggesting that comparative planning should be performed routinely for these patients.

ADVANCES IN KNOWLEDGE

We have reported that the clinical outcome of SGT patients treated with PT and compared IMPT to VMAT for the treatment of salivary gland tumour and have observed that protons delivered significantly less dose to organs at risks and were associated with less NTCP for xerostomia and dysphagia. Noteworthy, not using an up-front model-based approach, only 40% of our patients met the Dutch eligibility criteria.

Expert Consensus Statement: Management of Dysphagia in Head and Neck Cancer Patients

OBJECTIVE

To develop an expert consensus statement (ECS) on the management of dysphagia in head and neck cancer (HNC) patients to address controversies and offer opportunities for quality improvement. Dysphagia in HNC was defined as swallowing impairment in patients with cancers of the nasal cavity, paranasal sinuses, nasopharynx, oral cavity, oropharynx, larynx, or hypopharynx.

METHODS

Development group members with expertise in dysphagia followed established guidelines for developing ECS. A professional search strategist systematically reviewed the literature, and the best available evidence was used to compose consensus statements targeted at providers managing dysphagia in adult HNC populations. The development group prioritized topics where there was significant practice variation and topics that would improve the quality of HNC patient care if consensus were possible.

RESULTS

The development group identified 60 candidate consensus statements, based on 75 initial proposed topics and questions, that focused on addressing the following high yield topics: (1) risk factors, (2) screening, (3) evaluation, (4) prevention, (5) interventions, and (6) surveillance. After 2 iterations of the Delphi survey and the removal of duplicative statements, 48 statements met the standardized definition for consensus; 12 statements were designated as no consensus.

CONCLUSION

Expert consensus was achieved for 48 statements pertaining to risk factors, screening, evaluation, prevention, intervention, and surveillance for dysphagia in HNC patients. Clinicians can use these statements to improve quality of care, inform policy and protocols, and appreciate areas where there is no consensus. Future research, ideally randomized controlled trials, is warranted to address additional controversies related to dysphagia in HNC patients.

Machine learning for normal tissue complication probability prediction: Predictive power with versatility and easy implementation

Background and purpose

A popular Normal tissue Complication (NTCP) model deployed to predict radiotherapy (RT) toxicity is the Lyman-Burman Kutcher (LKB) model of tissue complication. Despite the LKB model's popularity, it can suffer from numerical instability and considers only the generalized mean dose (GMD) to an organ. Machine learning (ML) algorithms can potentially offer superior predictive power of the LKB model, and with fewer drawbacks. Here we examine the numerical characteristics and predictive power of the LKB model and compare these with those of ML.

Materials and methods

Both an LKB model and ML models were used to predict G2 Xerostomia on patients following RT for head and neck cancer, using the dose volume histogram of parotid glands as the input feature. Model speed, convergence characteristics and predictive power was evaluated on an independent training set.

Results

We found that only global optimization algorithms could guarantee a convergent and predictive LKB model. At the same time our results showed that ML models remained unconditionally convergent and predictive, while staying robust to gradient descent optimization. ML models outperform LKB in Brier score and accuracy but compare to LKB in ROC-AUC.

Conclusion

We have demonstrated that ML models can quantify NTCP better than or as well as LKB models, even for a toxicity that the LKB model is particularly well suited to predict. ML models can offer this performance while offering fundamental advantages in model convergence, speed, and flexibility, and so could offer an alternative to the LKB model that could potentially be used in clinical RT planning decisions.

Assessing the generalisability of radiomics features previously identified as predictive of radiation-induced sticky saliva and xerostomia

Background and purpose

While core to the scientific approach, reproducibility of experimental results is challenging in radiomics studies. A recent publication identified radiomics features that are predictive of late irradiation-induced toxicity in head and neck cancer (HNC) patients. In this study, we assessed the generalisability of these findings.

Materials and Methods

The procedure described in the publication in question was applied to a cohort of 109 HNC patients treated with 50-70 Gy in 20-35 fractions using helical radiotherapy although there were inherent differences between the two patient populations and methodologies. On each slice of the planning CT with delineated parotid and submandibular glands, the imaging features that were previously identified as predictive of moderate-to-severe xerostomia and sticky saliva 12 months post radiotherapy (Xer12m and SS12m) were calculated. Specifically, Short Run Emphasis (SRE) and maximum CT intensity (maxHU) were evaluated for improvement in prediction of Xer12m and SS12m respectively, compared to models solely using baseline toxicity and mean dose to the salivary glands.

Results

None of the associations previously identified as statistically significant and involving radiomics features in univariate or multivariate models could be reproduced on our cohort.

Conclusion

The discrepancies observed between the results of the two studies delineate limits to the generalisability of the previously reported findings. This may be explained by the differences in the approaches, in particular the imaging characteristics and subsequent methodological implementation. This highlights the importance of external validation, high quality reporting guidelines and standardisation protocols to ensure generalisability, replication and ultimately clinical implementation.

The course of swallowing problems in the first 2 years after diagnosis of head and neck cancer

INTRODUCTION

Head and neck cancer (HNC) and its treatment often negatively impact swallowing function. The aim was to investigate the course of patient-reported swallowing problems from diagnosis to 3, 6, 12, and 24 months after treatment, in relation to demographic, clinical, and lifestyle factors.

METHODS

Data were used of the Netherlands Quality of Life and Biomedical Cohort Study in head and neck cancer research (NET-QUBIC). The primary outcome measures were the subscales of the Swallowing Quality of Life Questionnaire (SWAL-QOL). Linear mixed-effects models (LMM) were conducted to investigate changes over time and associations with patient, clinical, and lifestyle parameters as assessed at baseline.

RESULTS

Data were available of 603 patients. There was a significant change over time on all subscales. Before treatment, 53% of patients reported swallowing problems. This number increased to 70% at M3 and decreased to 59% at M6, 50% at M12, and 48% at M24. Swallowing problems (i.e., longer eating duration) were more pronounced in the case of female, current smoking, weight loss prior to treatment, and stage III or IV tumor, and were more prevalent at 3 to 6 months after treatment. Especially patients with an oropharynx and oral cavity tumor, and patients receiving (C)RT following surgery or CRT only showed a longer eating duration after treatment, which did not return to baseline levels.

CONCLUSION

Half of the patients with HNC report swallowing problems before treatment. Eating duration was associated with sex, smoking, weight loss, tumor site and stage, and treatment modality, and was more pronounced 3 to 6 months after treatment.

The Dosimetric Outcome of a Rotational Planning Target Volume in Patients With Oropharyngeal Cancers

An isotropic expanded Planning Target Volume (PTV) neglects patient's off-axis rotation. This study designs a rotational PTV that is used instead of the standard 3-mm Clinical Target Volume (CTV) expanded PTV in oropharyngeal cancers with the goal to reduce pharyngeal constrictor muscle (PCM) mean dose. 10 patients were retrospectively evaluated. For off-axis rotation, the image was rotated around the longitudinal axis (cervical spinal canal) ± 5 degrees. These new CTVs were combined to form the rotational PTV. The standard and rotational treatment plans were designed with the goal to keep the superior and middle PCM-CTV70 mean dose to less than 50 Gy. There were a 355 cGy reduction in the superior PCM mean dose (form 5332 to 4977 cGy) and a 506 cGy reduction in middle PCM mean dose (from 4185 to 3679 cGy). 60% of patients may have at least a 20% reduction in dysphagia probability based on a Normal Tissue Complication Probability (NTCP) formula. The superior and middle PCM mean dose were reduced to less than 50 Gy in 40 and 20% of cases. There was an association between superior PCM mean dose and overlap volume of PTV70 and superior PCM in both standard (r = 0.92, p = 0.001) and rotational (r = 0.84, p = 0.002) plans. This association was present for middle PCM and PTV70 (r = 0.52, p = 0.02 and r = 0.62, p = 0.006). Rotational PTV can lower the mean dose to superior and middle PCMs, ultimately leading to lower dysphagia rates.

Technical note: Optimal allocation of limited proton therapy resources using model-based patient selection

PURPOSE

We consider the following scenario: A radiotherapy clinic has a limited number of proton therapy slots available each day to treat cancer patients of a given tumor site. The clinic's goal is to minimize the expected number of complications in the cohort of all patients of that tumor site treated at the clinic, and thereby maximize the benefit of its limited proton resources.

METHODS

To address this problem, we extend the normal tissue complication probability (NTCP) model-based approach to proton therapy patient selection to the situation of limited resources at a given institution. We assume that, on each day, a newly diagnosed patient is scheduled for treatment at the clinic with some probability and with some benefit Δ N T C P $\Delta NTCP$ from protons over photons, which is drawn from a probability distribution. When a new patient is scheduled for treatment, a decision for protons or photons must be made, and a patient may wait only for a limited amount of time for a proton slot becoming available. The goal is to determine the Δ N T C P $\Delta NTCP$ thresholds for selecting a patient for proton therapy, which optimally balance the competing goals of making use of all available slots while not blocking slots with patients with low benefit. This problem can be formulated as a Markov decision process (MDP) and the optimal thresholds can be determined via a value-policy iteration method.

RESULTS

The optimal Δ N T C P $\Delta NTCP$ thresholds depend on the number of available proton slots, the average number of patients under treatment, and the distribution of Δ N T C P $\Delta NTCP$ values. In addition, the optimal thresholds depend on the current utilization of the facility. For example, if one proton slot is available and a second frees up shortly, the optimal Δ N T C P $\Delta NTCP$ threshold is lower compared to a situation where all but one slot remain blocked for longer.

CONCLUSIONS

MDP methodology can be used to augment current NTCP model-based patient selection methods to the situation that, on any given day, the number of proton slots is limited. The optimal Δ N T C P $\Delta NTCP$ threshold then depends on the current utilization of the proton facility. Although, the optimal policy yields only a small nominal benefit over a constant threshold, it is more robust against variations in patient load.

Adaptive Proton Therapy of Pediatric Head and Neck Cases Using MRI-Based Synthetic CTs: Initial Experience of the Prospective KiAPT Study

BACKGROUND AND PURPOSE

Interfractional anatomical changes might affect the outcome of proton therapy (PT). We aimed to prospectively evaluate the role of Magnetic Resonance Imaging (MRI) based adaptive PT for children with tumors of the head and neck and base of skull.

METHODS

MRI verification images were acquired at half of the treatment course. A synthetic computed tomography (CT) image was created using this MRI and a deformable image registration (DIR) to the reference MRI. The methodology was verified with in-silico phantoms and validated using a clinical case with a shrinking cystic hygroma on the basis of dosimetric quantities of contoured structures. The dose distributions on the verification X-ray CT and on the synthetic CT were compared with a gamma-index test using global 2 mm/2% criteria.

RESULTS

Regarding the clinical validation case, the gamma-index pass rate was 98.3%. Eleven patients were included in the clinical study. The most common diagnosis was rhabdomyosarcoma (73%). Craniofacial tumor site was predominant in 64% of patients, followed by base of skull (18%). For one individual case the synthetic CT showed an increase in the median D2 and Dmax dose on the spinal cord from 20.5 GyRBE to 24.8 GyRBE and 14.7 GyRBE to 25.1 GyRBE, respectively. Otherwise, doses received by OARs remained relatively stable. Similarly, the target volume coverage seen by D95% and V95% remained unchanged.

CONCLUSIONS

The method of transferring anatomical changes from MRIs to a synthetic CTs was successfully implemented and validated with simple, commonly available tools. In the frame of our early results on a small cohort, no clinical relevant deterioration for neither PTV coverage nor an increased dose burden to OARs occurred. However, the study will be continued to identify a pediatric patient cohort, which benefits from adaptive treatment planning.

Proton Therapy for Squamous Cell Carcinoma of the Head and Neck: Early Clinical Experience and Current Challenges

Simple Summary

Proton therapy is a promising type of radiation therapy used to destroy tumor cells. It has the potential to further improve the outcomes for patients with head and neck cancer since it allows to minimize the radiation dose to vital structures around the tumor, leading to less toxicity. This paper describes the current experience worldwide with proton therapy in head and neck cancer.

Abstract

Proton therapy (PT) is a promising development in radiation oncology, with the potential to further improve outcomes for patients with squamous cell carcinoma of the head and neck (HNSCC). By utilizing the finite range of protons, healthy tissue can be spared from beam exit doses that would otherwise be irradiated with photon-based treatments. Current evidence on PT for HNSCC is limited to comparative dosimetric analyses and retrospective single-institution series. As a consequence, the recognized indications for the reimbursement of PT remain scarce in most countries. Nevertheless, approximately 100 PT centers are in operation worldwide, and initial experiences for HNSCC are being reported. This review aims to summarize the results of the early clinical experience with PT for HNSCC and the challenges that are currently faced.

MR-Guided Adaptive Radiotherapy for OAR Sparing in Head and Neck Cancers

Simple Summary

Normal tissue toxicities in head and neck cancer persist as a cause of decreased quality of life and are associated with poorer treatment outcomes. The aim of this article is to review organ at risk (OAR) sparing approaches available in MR-guided adaptive radiotherapy and present future developments which hope to improve treatment outcomes. Increasing the spatial conformity of dose distributions in radiotherapy is an important first step in reducing normal tissue toxicities, and MR-guided treatment devices presents a new opportunity to use biological information to drive treatment decisions on a personalized basis.

Abstract

MR-linac devices offer the potential for advancements in radiotherapy (RT) treatment of head and neck cancer (HNC) by using daily MR imaging performed at the time and setup of treatment delivery. This article aims to present a review of current adaptive RT (ART) methods on MR-Linac devices directed towards the sparing of organs at risk (OAR) and a view of future adaptive techniques seeking to improve the therapeutic ratio. This ratio expresses the relationship between the probability of tumor control and the probability of normal tissue damage and is thus an important conceptual metric of success in the sparing of OARs. Increasing spatial conformity of dose distributions to target volume and OARs is an initial step in achieving therapeutic improvements, followed by the use of imaging and clinical biomarkers to inform the clinical decision-making process in an ART paradigm. Pre-clinical and clinical findings support the incorporation of biomarkers into ART protocols and investment into further research to explore imaging biomarkers by taking advantage of the daily MR imaging workflow. A coherent understanding of this road map for RT in HNC is critical for directing future research efforts related to sparing OARs using image-guided radiotherapy (IGRT).

The dosimetric and clinical advantages of the GTV-CTV-PTV margins reduction by 6 mm in head and neck squamous cell carcinoma: Significant acute and late toxicity reduction

PURPOSE

We aim to identify the dosimetric and clinical impact of reducing the total GTV-CTV-PTV margins in head-and-neck squamous cell carcinoma (HNSCC) treated with definitive (chemo)radiation.

MATERIALS AND METHODS

The acute and late toxicity and outcomes of 155 consecutive patients treated between February 2017 and March 2019 with GTV-CTV-PTV margins of 9 mm were compared to those of 155 consecutive patients treated with total margin of 15 mm margin, before April 2015. All patients were treated with VMAT with daily-image guidance using CBCT.

RESULTS

Reducing the GTV-CTV-PTV by 6 mm resulted in significant reduction of total irradiated volume (PTV-total) by a median of 28.1% and significant reduction of doses to all salivary glands (largest reduction ipsilateral parotid gland; median -9.6 Gy) and constrictor muscle (-6.1 Gy) with subsequent reduction of the incidence of overall acute grade 3 toxicity (47.7% for 9 mm and 66.5% for 15 mm groups, p = 0.001), grade 3 mucositis (18.1% vs. 35.5%, p < 0.001) and feeding tube-dependency at the end of treatment (24.5% vs. 40%, p = 0.005). The incidence of late grade ≥ 2 xerostomia and dysphagia were also significantly lower in the 9 mm group (31.7% vs. 58.6% p < 0.001, and 15.4% vs. 26.7%, p = 0.04). The 2-year rates of loco-regional control, disease-free and overall survival were 78.8% vs.75.8%, 70.9% vs. 64.4%, and 83.8% vs. 67.6%, (p > 0.05, all).

CONCLUSION

Reduction of the total GTV-CTV-PTV margins from 15 to 9 mm in HNSCC significantly reduced the irradiated volumes and the dose to salivary glands and constrictor muscle with significant reduction of radiation-related toxicity. The loco-regional control rates of both groups were comparable.

Proton Radiation Therapy for Nasopharyngeal Cancer Patients: Dosimetric and NTCP Evaluation Supporting Clinical Decision

(1) Background: we proposed an integrated strategy to support clinical allocation of nasopharyngeal patients between proton and photon radiotherapy. (2) Methods: intensity-modulated proton therapy (IMPT) plans were optimized for 50 consecutive nasopharyngeal carcinoma (NPC) patients treated with volumetric modulated arc therapy (VMAT), and differences in dose and normal tissue complication probability (ΔNTCPx-p) for 16 models were calculated. Patient eligibility for IMPT was assessed using a model-based selection (MBS) strategy following the results for 7/16 models describing the most clinically relevant endpoints, applying a model-specific ΔNTCPx-p threshold (15% to 5% depending on the severity of the complication) and a composite threshold (35%). In addition, a comprehensive toxicity score (CTS) was defined as the weighted sum of all 16 ΔNTCPx-p, where weights follow a clinical rationale. (3) Results: Dose deviations were in favor of IMPT (ΔD_mean ≥ 14% for cord, esophagus, brainstem, and glottic larynx). The risk of toxicity significantly decreased for xerostomia (-12.5%), brain necrosis (-2.3%), mucositis (-3.2%), tinnitus (-8.6%), hypothyroidism (-9.3%), and trismus (-5.4%). There were 40% of the patients that resulted as eligible for IMPT, with a greater advantage for T3-T4 staging. Significantly different CTS were observed in patients qualifying for IMPT. (4) Conclusions: The MBS strategy successfully drives the clinical identification of NPC patients, who are most likely to benefit from IMPT. CTS summarizes well the expected global gain.

Parotid Gland Stem Cell Sparing Radiation Therapy for Patients With Head and Neck Cancer: A Double-Blind Randomized Controlled Trial

PURPOSE

Radiation therapy for head and neck cancer frequently leads to salivary gland damage and subsequent xerostomia. The radiation response of the parotid glands of rats, mice, and patients critically depends on dose to parotid gland stem cells, mainly located in the gland's main ducts (stem cell rich [SCR] region). Therefore, this double-blind randomized controlled trial aimed to test the hypothesis that parotid gland stem cell sparing radiation therapy preserves parotid gland function better than currently used whole parotid gland sparing radiation therapy.

METHODS AND MATERIALS

Patients with head and neck cancer (n = 102) treated with definitive radiation therapy were randomized between standard parotid-sparing and stem cell sparing (SCS) techniques. The primary endpoint was >75% reduction in parotid gland saliva production compared with pretreatment production (FLOW12M). Secondary endpoints were several aspects of xerostomia 12 months after treatment.

RESULTS

Fifty-four patients were assigned to the standard arm and 48 to the SCS arm. Only dose to the SCR regions (contralateral 16 and 11 Gy [P = .004] and ipsilateral 26 and 16 Gy [P = .001] in the standard and SCS arm, respectively) and pretreatment patient-rated daytime xerostomia (35% and 13% [P = .01] in the standard and SCS arm, respectively) differed significantly between the arms. In the SCS arm, 1 patient (2.8%) experienced FLOW12M compared with 2 (4.9%) in the standard arm (P = 1.00). However, a trend toward better relative parotid gland salivary function in favor of SCS radiation therapy was shown. Moreover, multivariable analysis showed that mean contralateral SCR region dose was the strongest dosimetric predictor for moderate-to-severe patient-rated daytime xerostomia and grade ≥2 physician-rated xerostomia, the latter including reported alteration in diet.

CONCLUSIONS

No significantly better parotid function was observed in SCS radiation therapy. However, additional multivariable analysis showed that dose to the SCR region was more predictive of the development of parotid gland function-related xerostomia endpoints than dose to the entire parotid gland.

Swallowing sparing intensity modulated radiotherapy versus standard parotid sparing intensity-modulated radiotherapy for treatment of head and neck cancer: a randomized clinical trial

BACKGROUND

Dysphagia is a distressing symptom during and after radiotherapy treatment in head and neck cancer (HNC) patients. The objective of this prospective study was to investigate whether swallowing sparing intensity modulated radiotherapy (SW-IMRT) reduces the occurrence of swallowing dysfunction compared to the standard IMRT (ST-IMRT).

METHODS

We randomized, planned, and treated patients with HNC who needed whole neck irradiation using the simultaneous integrated boost (SIB) IMRT technique. Doses of 70, 60, and 54 Gy (over 33 daily fractions) were prescribed to the primary tumor, high-risk and low-risk regions, respectively. The postoperative cases received 60 and 54 Gy (over 30 daily fractions) to the high-risk planning target volume (PTV) and low-risk PTV. We contoured organs at risk related to swallowing dysfunction (SWOARs) in all cases. In the ST-IMRT group, parotids only were spared. In the SW-IMRT group, parotids and SWOARs outside the high-risk PTV were spared. Assessment of dysphagia included clinical and instrumental evaluation.

RESULTS

One hundred forty-six patients ended their radiotherapy treatment. Dose distribution showed comparable PTV coverage and no difference in parotid glands sparing between the two groups. SWOARs dose reduction with SW-IMRT differs according to tumor location and its overlap with SWOARs. Using different assessment methods, SW-IMRT was associated with a lower occurrence of dysphagia up to one year after treatment. There was no difference between the two groups regarding acute dysphagia (p = 0.262), overall survival (p = 0.811), and disease-free survival (p = 0.876).

CONCLUSION

SW-IMRT is significantly better than ST-IMRT regarding a physician-rated and objective assessment of swallowing dysfunction at short- and long-term post-treatment follow-up.

Improvement in Dysphagia Outcomes Following Clinical Target Volume Reduction in the De-ESCALaTE Study

AIMS

The De-ESCALaTE study showed an overall survival advantage for the administration of synchronous cisplatin chemotherapy with radiotherapy in low-risk oropharyngeal cancer when compared with synchronous cetuximab. During the trial, a radiotherapy quality assurance protocol amendment permitted centres to swap from the original radiotherapy contouring protocol (incorporating the whole oropharynx into the high-dose clinical target volume (CTV); anatomical protocol) to a protocol that incorporated the gross tumour volume with a 10 mm margin into the CTV (volumetric protocol). The purpose of this study was to examine both toxicity and tumour control related to this protocol amendment.

MATERIALS AND METHODS

Overall survival and recurrence at 2 years were used to compare tumour control in the two contouring cohorts. For toxicity, the cohorts were compared by both the number of severe (grades 3-5) and all grades acute and late toxicities. In addition, quality of life and swallowing were compared using EORTC-C30 and MD Anderson Dysphagia Inventory, respectively.

RESULTS

Of 327 patients included in this study, 185 were contoured according to the anatomical protocol and 142 by the volumetric protocol. The two cohorts were well balanced, with the exception of significantly more patients in the anatomical cohort undergoing prophylactic feeding tube insertion (P < 0.001). With a minimum of 2 years of follow-up there was no significant difference in overall survival or recurrence between the two contouring protocols. Similarly, there was no significant difference in the rate of reported severe or all grades acute or late toxicity and no sustained significant difference in quality of life. However, there was a significant difference in favour of volumetric contouring in several domains of the MD Anderson Dysphagia Inventory questionnaire at 1 year, which persisted to 2 years in the dysphagia functional (P = 0.002), dysphagia physical (P = 0.009) and dysphagia overall function (P = 0.008) domains.

CONCLUSION

In the context of the unplanned post-hoc analysis of a randomised trial, measurable improvement in long-term dysphagia has been shown following a reduction in the CTV. Further reductions in the CTV should be subject to similar scrutiny within the confines of a prospective study.

A two-stage genome-wide association study of radiation-induced acute toxicity in head and neck cancer

BACKGROUND

Most head and neck cancer (HNC) patients receive radiotherapy (RT) and develop toxicities. This genome-wide association study (GWAS) was designed to identify single nucleotide polymorphisms (SNPs) associated with common acute radiation-induced toxicities (RITs) in an HNC cohort.

METHODS

A two-stage GWAS was performed in 1279 HNC patients treated with RT and prospectively scored for mucositis, xerostomia, sticky saliva, and dysphagia. The area under the curve (AUC) was used to estimate the average load of toxicity during RT. At the discovery study, multivariate linear regression was used in 957 patients, and the top-ranking SNPs were tested in 322 independent replication cohort. Next, the discovery and the replication studies were meta-analyzed.

RESULTS

A region on 5q21.3 containing 16 SNPs showed genome-wide (GW) significance association at P-value < 5.0 × 10-8 with patient-rated acute xerostomia in the discovery study. The top signal was rs35542 with an adjusted effect size of 0.17*A (95% CI 0.12 to 0.23; P-value <  = 3.78 × 10-9). The genome wide significant SNPs were located within three genes (EFNA5, FBXL17, and FER). In-silico functional analysis showed these genes may be involved in DNA damage response and co-expressed in minor salivary glands. We found 428 suggestive SNPs (P-value < 1.0 × 10-5) for other toxicities, taken to the replication study. Eleven of them showed a nominal association (P-value < 0.05).

CONCLUSIONS

This GWAS suggested novel SNPs for patient-rated acute xerostomia in HNC patients. If validated, these SNPs and their related functional pathways could lead to a predictive assay to identify sensitive patients to radiation, which may eventually allow a more individualized RT treatment.

Development and external validation of a prediction model for tube feeding dependency for at least four weeks during chemoradiotherapy for head and neck cancer

BACKGROUND & AIMS

Patients who receive chemoradiotherapy or bioradiotherapy (CRT/BRT) for locally advanced head and neck squamous cell carcinoma (LAHNSCC) often experience high toxicity rates interfering with oral intake, causing tube feeding (TF) dependency. International guidelines recommend gastrostomy insertion when the expected use of TF exceeds 4 weeks. We aimed to develop and externally validate a prediction model to identify patients who need TF ≥ 4 weeks and would benefit from prophylactic gastrostomy insertion.

METHODS

A retrospective multicenter cohort study was performed in four tertiary head and neck cancer centers in the Netherlands. The prediction model was developed using data from University Medical Center Utrecht and the Netherlands Cancer Institute and externally validated using data from Maastricht University Medical Center and Radboud University Medical Center. The primary endpoint was TF dependency ≥4 weeks initiated during CRT/BRT or within 30 days after CRT/BRT completion. Potential predictors were extracted from electronic health records and radiotherapy dose-volume parameters were calculated.

RESULTS

The developmental and validation cohort included 409 and 334 patients respectively. Multivariable analysis showed predictive value for pretreatment weight change, texture modified diet at baseline, ECOG performance status, tumor site, N classification, mean radiation dose to the contralateral parotid gland and oral cavity. The area under the receiver operating characteristics curve for this model was 0.73 and after external validation 0.62. Positive and negative predictive value for a risk of 90% or higher for TF dependency ≥4 weeks were 81.8% and 42.3% respectively.

CONCLUSIONS

We developed and externally validated a prediction model to estimate TF-dependency ≥4 weeks in LAHNSCC patients treated with CRT/BRT. This model can be used to guide personalized decision-making on prophylactic gastrostomy insertion in clinical practice.

Functional swallowing outcomes related to radiation exposure to dysphagia and aspiration-related structures in patients with head and neck cancer undergoing definitive and postoperative intensity-modulated radiotherapy

BACKGROUND

The relationship between swallowing outcomes and radiotherapy dose to dysphagia and aspiration-related structures (DARS) may be different following definitive versus postoperative radiotherapy (PORT) for mucosal head and neck cancer (HNC) and has not been well-studied.

METHOD

Patient- and clinician-reported swallowing measures were prospectively collected at six time points from baseline to 24 months postradiotherapy HNC. Radiotherapy plans were retrospectively analyzed to assess dose delivered to DARS. The association between swallowing outcomes and participant demographics, tumor characteristics, and radiotherapy dose in definitive and postoperative treatment cohorts was assessed.

RESULTS

Ninety-three participants who received radiotherapy for HNC were included in the analysis (n = 49 definitive radiotherapy for laryngeal/pharyngeal primary tumors and n = 44 postoperative PORT for predominantly oral cavity/salivary gland tumors). Participants undergoing PORT had lower doses to DARS than those undergoing definitive RT. High dose to the pharyngeal constrictors and base of tongue for definitive RT and the esophageal inlet, supraglottic larynx and cervical esophagus for the PORT group were associated with worse swallowing function.

CONCLUSION

Radiation dose to DARS is associated with post-treatment swallowing outcomes. These dose/outcome relationships may vary between the definitive and postoperative settings.

Proton Therapy in Head and Neck Cancer Treatment: State of the Problem and Development Prospects (Review)

Proton therapy (PT) due to dosimetric characteristics (Bragg peak formation, sharp dose slowdown) is currently one of the most high-tech techniques of radiation therapy exceeding the standards of photon methods.

In recent decades, PT has traditionally been used, primarily, for head and neck cancers (HNC) including skull base tumors. Regardless of the fact that recently PT application area has significantly expanded, HNC still remain a leading indication for proton radiation since PT’s physic-dosimetric and radiobiological advantages enable to achieve the best treatment results in these tumors.

The present review is devoted to PT usage in HNC treatment in the world and Russian medicine, the prospects for further technique development, the assessment of PT’s radiobiological features, a physical and dosimetric comparison of protons photons distribution. The paper shows PT’s capabilities in the treatment of skull base tumors, HNC (nasal cavity, paranasal sinuses, nasopharynx, oropharynx, and laryngopharynx, etc.), eye tumors, sialomas. The authors analyze the studies on repeated radiation and provide recent experimental data on favorable profile of proton radiation compared to the conventional radiation therapy.

The review enables to conclude that currently PT is a dynamic radiation technique opening up new opportunities for improving therapy of oncology patients, especially those with HNC.

Can the mean linear energy transfer of organs be directly related to patient toxicities for current head and neck cancer intensity-modulated proton therapy practice?

BACKGROUND AND PURPOSE

The relative biological effectiveness (RBE) of proton therapy is predicted to vary with the dose-weighted average linear energy transfer (LET_d). However, RBE values may substantially vary for different clinical endpoints. Therefore, the aim of this study was to assess the feasibility of relating mean D⋅LET_d parameters to patient toxicity for HNC patients treated with proton therapy.

MATERIALS AND METHODS

The delivered physical dose (D) and the voxel-wise product of D and LET_d (D⋅LET_d) distributions were calculated for 100 head and neck cancer (HNC) proton therapy patients using our TPS (Raystation v6R). The means and covariance matrix of the accumulated D and D⋅LET_d of all relevant organs-at-risk (OARs) were used to simulate 2.500 data sets of different sizes. For each dataset, an attempt was made to add mean D⋅LET_d parameters to a multivariable NTCP model based on mean D parameters of the same OAR for xerostomia, tube feeding and dysphagia. The likelihood of creating an NTCP model with statistically significant parameters (i.e. power) was calculated as a function of the simulated sample size for various RBE models.

RESULTS

The sample size required to have a power of at least 80% to show an independent effect of mean D⋅LET_d parameters on toxicity is over 15,000 patients for all toxicities.

CONCLUSION

For current clinical practice, it is not feasible to directly model NTCP with both mean D and mean D⋅LET_d of OARs. These findings should not be interpreted as a contradiction of previous evidence for the relationship between RBE and LET_d.

Optimal Allocation of Proton Therapy Slots in Combined Proton-Photon Radiation Therapy

PURPOSE

Proton therapy is a limited resource that is not available to all patients who may benefit from it. We investigated combined proton-photon treatments, in which some fractions are delivered with protons and the remaining fractions with photons, as an approach to maximize the benefit of limited proton therapy resources at a population level.

METHODS AND MATERIALS

To quantify differences in normal-tissue complication probability (NTCP) between protons and photons, we considered a cohort of 45 patients with head and neck cancer for whom intensity modulated radiation therapy and intensity modulated proton therapy plans were previously created, in combination with NTCP models for xerostomia and dysphagia considered in the Netherlands for proton patient selection. Assuming limited availability of proton slots, we developed methods to optimally assign proton fractions in combined proton-photon treatments to minimize the average NTCP on a population level. The combined treatments were compared with patient selection strategies in which patients are assigned to single-modality proton or photon treatments.

RESULTS

There is a benefit of combined proton-photon treatments compared with patient selection, owing to the nonlinearity of NTCP functions; that is, the initial proton fractions are the most beneficial, whereas additional proton fractions have a decreasing benefit when a flatter part of the NTCP curve is reached. This effect was small for the patient cohort and NTCP models considered, but it may be larger if dose-response relationships are better known. In addition, when proton slots are limited, patient selection methods face a trade-off between leaving slots unused and blocking slots for future patients who may have a larger benefit. Combined proton-photon treatments with flexible proton slot assignment provide a method to make optimal use of all available resources.

CONCLUSIONS

Combined proton-photon treatments allow for better use of limited proton therapy resources. The benefit over patient selection schemes depends on the NTCP models and the dose differences between protons and photons.

Optimizing oropharyngeal cancer management by using proton beam therapy: trends of cost-effectiveness

Background

Proton beam therapy (PBT) is a new-emerging cancer treatment in China but its treatment costs are high and not yet covered by Chinese public medical insurance. The advanced form of PBT, intensity-modulated proton radiation therapy (IMPT), has been confirmed to reduce normal tissue complication probability (NTCP) as compared to conventional intensity-modulated photon-radiation therapy (IMRT) in patients with oropharyngeal cancer (OPC). Herein, we evaluated the cost-effectiveness and applicability of IMPT versus IMRT for OPC patients in China, aiming at guiding the proper use of PBT.

Methods

A 7-state Markov model was designed for analysis. Base-case evaluation was performed on a 56-year-old (median age of OPC in China) patient under the assumption that IMPT could provide a 25% NTCP-reduction in long-term symptomatic dysphagia and xerostomia. Model robustness was examined using probabilistic sensitivity analysis, cohort analysis, and tornado diagram. One-way sensitivity analyses were conducted to identify the cost-effective scenarios. IMPT was considered as cost-effective if the incremental cost-effectiveness ratio (ICER) was below the societal willingness-to-pay (WTP) threshold.

Results

Compared with IMRT, IMPT provided an extra 0.205 quality-adjusted life-year (QALY) at an additional cost of 34,926.6 US dollars ($), and had an ICER of $170,082.4/ QALY for the base case. At the current WTP of China ($33,558 / QALY) and a current IMPT treatment costs of $50,000, IMPT should provide a minimum NTCP-reduction of 47.5, 50.8, 55.6, 63.3 and 77.2% to be considered cost-effective for patient age levels of 10, 20, 30, 40 and 50-year-old, respectively. For patients at the median age level, reducing the current IMPT costs ($50,000) to a $30,000 level would make the minimum NTCP-reduction threshold for “cost-effective” decrease from 91.4 to 44.6%, at the current WTP of China (from 69.0 to 33.5%, at a WTP of $50,000 / QALY; and from 39.7 to 19.1%, at a WTP of $100,000 / QALY).

Conclusions

Cost-effective scenarios of PBT exist in Chinese OPC patients at the current WTP of China. Considering a potential upcoming increase in PBT use in China, such cost-effective scenarios may further expand if a decrease of proton treatment costs occurs or an increase of WTP level.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08638-2.

Radiation-induced swallowing dysfunction in patients with head and neck cancer: A literature review

Swallowing dysfunction is a prevailing state following radiotherapy in patients with head and neck cancer. Following the advancement of cancer treatment in recent years, the survival rate of head and neck cancer has gradually increased. Simultaneously, patients with head and neck cancer suffer due to the long-duration and more prominent swallowing dysfunction states. Based on an extensive literature review, we aimed to explore the mechanisms, risk factors, and clinical evaluations of swallowing dysfunction and their related symptoms following radiotherapy. These include functional changes of the muscles, trismus, xerostomia, neuropathy, and lymphedema. When swallowing dysfunction occurs, patients usually seek medical help and are referred for rehabilitation therapy, such as muscle strengthening and tongue resistance exercise. Furthermore, clinicians should discuss with patients how and when to place the feeding tube. Only through detailed evaluation and management can swallowing dysfunction resolve and improve the quality of life of patients with head and neck cancer following radiotherapy.

National Protocol for Model-Based Selection for Proton Therapy in Head and Neck Cancer

In the Netherlands, the model-based approach is used to identify patients with head and neck cancer who may benefit most from proton therapy in terms of prevention of late radiation-induced side effects in comparison with photon therapy. To this purpose, a National Indication Protocol Proton therapy for Head and Neck Cancer patients (NIPP-HNC) was developed, which has been approved by the health care authorities. When patients qualify according to the guidelines of the NIPP-HNC, proton therapy is fully reimbursed. This article describes the procedures that were followed to develop this NIPP-HNC and provides all necessary information to introduce model-based selection for patients with head and neck cancer into routine clinical practice.

Methodologies to Increase the Level of Evidence of Real-life Proton Therapy in Head and Neck Tumors

This review aims to present and assess available and new methodologies to increase the clinical evidence of proton therapy data for patients with head and neck cancer. Despite the increasing number of scientific reports showing the feasibility and effectiveness of proton therapy in head and neck cancer, clinical evidence on the potential benefits of its use remains low for several reasons. In this article, the pros and cons of consolidated and new methodologies in this setting such as randomized clinical trials, the model-based approach, and the use of prospective multicentric registries will be detailed.

Prophylactic gastrostomy in locally advanced head and neck cancer: results of a national survey among radiation oncologists

BACKGROUND

Nutritional complications in patients with locally advanced head and neck cancer (LA-HNC) treated by concurrent chemoradiotherapy (CCRT) often lead to placement of a prophylactic gastrostomy (PG) tube, while indication lacks harmonization. Our aim was to explore the current PG tube utilization among Belgian radiation oncology centers.

METHODS

A survey was distributed to all 24 Belgian Radiation oncology departments, with questions about the number of patient treated per year, whether the PG indication is discussed at the multidisciplinary board, placement technique, time of starting nutrition and removal, its impact on swallowing function and importance of clinical factors. For the latter Relative Importance and Discordance Indexes were calculated to describe the ranking and agreement.

RESULTS

All 24 centers submitted the questionnaire. Twenty three treat more than 20 head and neck (HNC) patients per year, while four (1 in 21-50; 3 in 51-100) are not discussing the gastrostomy tube indication at the multidisciplinary board. For the latter, endoscopic placement (68%) is the dominant technique, followed by the radiologic (16%) and laparoscopic (16%) methods. Seventy-five percent start the enteral nutrition when clinically indicated, 17% immediately and 8% from the start of radiotherapy. Majority of specialists (19/24) keep the gastrostomy tube until the patient assume an adequate oral feeding. Fifteen centres are considering PG decrease swallowing function. Regarding factors and their importance in the decision for the PG, foreseen irradiated volume reached highest importance, followed by 'anatomical site', 'patients' choice' and 'postoperative versus definitive' and 'local expertise', with decreasing importance respectively. Disagreement indexes showed moderate variation.

CONCLUSIONS

The use of a PG tube for LAHNC patients treated by CCRT shows disparity at national level. Prospective studies are needed to ensure proper indication of this supportive measure.

Assessment of the confidence interval in the multivariable normal tissue complication probability model for predicting radiation-induced liver disease in primary liver cancer

We developed a confidence interval-(CI) assessing model in multivariable normal tissue complication probability (NTCP) modeling for predicting radiation-induced liver disease (RILD) in primary liver cancer patients using clinical and dosimetric data. Both the mean NTCP and difference in the mean NTCP (ΔNTCP) between two treatment plans of different radiotherapy modalities were further evaluated and their CIs were assessed. Clinical data were retrospectively reviewed in 322 patients with hepatocellular carcinoma (n = 215) and intrahepatic cholangiocarcinoma (n = 107) treated with photon therapy. Dose-volume histograms of normal liver were reduced to mean liver dose (MLD) based on the fraction size-adjusted equivalent uniform dose. The most predictive variables were used to build the model based on multivariable logistic regression analysis with bootstrapping. Internal validation was performed using the cross-validation leave-one-out method. Both the mean NTCP and the mean ΔNTCP with 95% CIs were calculated from computationally generated multivariate random sets of NTCP model parameters using variance-covariance matrix information. RILD occurred in 108/322 patients (33.5%). The NTCP model with three clinical and one dosimetric parameter (tumor type, Child-Pugh class, hepatitis infection status and MLD) was most predictive, with an area under the receiver operative characteristics curve (AUC) of 0.79 (95% CI 0.74-0.84). In eight clinical subgroups based on the three clinical parameters, both the mean NTCP and the mean ΔNTCP with 95% CIs were able to be estimated computationally. The multivariable NTCP model with the assessment of 95% CIs has potential to improve the reliability of the NTCP model-based approach to select the appropriate radiotherapy modality for each patient.

Effect of Pretreatment Dysphagia on Postchemoradiation Swallowing Function in Head and Neck Cancer

OBJECTIVES

Chemoradiation therapy (CRT) for head and neck cancer can have profound effects on swallowing function. Identification of risk factors for development of swallowing dysfunction after CRT may improve allocation of preventive strategies. The purpose of this study is to determine the association between pre-CRT dysphagia and post-CRT swallowing dysfunction.

STUDY DESIGN

Retrospective cohort study.

SETTING

Academic medical center.

METHODS

Patients with head and neck cancer were evaluated before and 3 months after CRT. Dysphagia was assessed with the Eating Assessment Tool (EAT-10). Swallowing dysfunction was evaluated by a videofluoroscopic swallow study and the Penetration-Aspiration Scale and swallowing safety was evaluated by the Functional Oral Intake Scale. The association between pre-CRT EAT-10 scores and post-CRT swallowing dysfunction was evaluated.

RESULTS

The mean ± SD post-CRT Functional Oral Intake Scale score was 6.5 ± 1.2 for individuals with a pre-CRT EAT-10 score <3 and 5.3 ± 1.9 for those with a pre-CRT EAT-10 score ≥3 (P < .001). The mean post-CRT Penetration-Aspiration Scale score was 2.2 ± 1.5 for individuals with a pre-CRT EAT-10 score <3 and 3.8 ± 2.6 for those with a pre-CRT EAT-10 score ≥3 (P < .001). After multivariate analysis adjusting for age, tumor subsite, T classification, and primary surgery, pre-CRT dysphagia (EAT-10 ≥3) was an independent predictor of post-CRT aspiration (odds ratio, 4.19 [95% CI, 1.08-16.20]; P = .04) and feeding tube dependence (odds ratio, 3.54 [95% CI, 1.01-12.33]; P = .04).

CONCLUSION

The presence of dysphagia before chemoradiation for head and neck cancer is an independent predictor of swallowing dysfunction after completion of therapy. These results may help target intervention toward preventing swallowing dysfunction in high-risk individuals.