Development of a multivariable normal tissue complication probability (NTCP) model for tube feeding dependence after curative radiotherapy/chemo-radiotherapy in head and neck cancer

Cluster-Based Toxicity Estimation of Osteoradionecrosis Via Unsupervised Machine Learning: Moving Beyond Single Dose-Parameter Normal Tissue Complication Probability by Using Whole Dose-Volume Histograms for Cohort Risk Stratification

PURPOSE

Given the limitations of extant models for normal tissue complication probability estimation for osteoradionecrosis (ORN) of the mandible, the purpose of this study was to enrich statistical inference by exploiting structural properties of data and provide a clinically reliable model for ORN risk evaluation through an unsupervised-learning analysis that incorporates the whole radiation dose distribution on the mandible.

METHODS AND MATERIALS

The analysis was conducted on retrospective data of 1259 patients with head and neck cancer treated at The University of Texas MD Anderson Cancer Center between 2005 and 2015. During a minimum 12-month posttherapy follow-up period, 173 patients in this cohort (13.7%) developed ORN (grades I to IV). The (structural) clusters of mandibular dose-volume histograms (DVHs) for these patients were identified using the K-means clustering method. A soft-margin support vector machine was used to determine the cluster borders and partition the dose-volume space. The risk of ORN for each dose-volume region was calculated based on incidence rates and other clinical risk factors.

RESULTS

The K-means clustering method identified 6 clusters among the DVHs. Based on the first 5 clusters, the dose-volume space was partitioned by the soft-margin support vector machine into distinct regions with different risk indices. The sixth cluster entirely overlapped with the others; the region of this cluster was determined by its envelopes. For each region, the ORN incidence rate per preradiation dental extraction status (a statistically significant, nondose related risk factor for ORN) was reported as the corresponding risk index.

CONCLUSIONS

This study presents an unsupervised-learning analysis of a large-scale data set to evaluate the risk of mandibular ORN among patients with head and neck cancer. The results provide a visual risk-assessment tool for ORN (based on the whole DVH and preradiation dental extraction status) as well as a range of constraints for dose optimization under different risk levels.

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.

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.

Proton arc therapy increases the benefit of proton therapy for oropharyngeal cancer patients in the model based clinic

BACKGROUND AND PURPOSE

In the model-based approach, patients qualify for proton therapy when the reduction in risk of toxicity (ΔNTCP) obtained with IMPT relative to VMAT is larger than predefined thresholds as defined by the Dutch National Indication Protocol (NIPP). Proton arc therapy (PAT) is an emerging technology which has the potential to further decrease NTCPs compared to IMPT. The aim of this study was to investigate the potential impact of PAT on the number of oropharyngeal cancer (OPC) patients that qualify for proton therapy.

MATERIALS AND METHODS

A prospective cohort of 223 OPC patients subjected to the model-based selection procedure was investigated. 33 (15%) patients were considered unsuitable for proton treatment before plan comparison. When IMPT was compared to VMAT for the remaining 190 patients, 148 (66%) patients qualified for protons and 42 (19%) patients did not. For these 42 patients treated with VMAT, robust PAT plans were generated.

RESULTS

PAT plans provided better or similar target coverage compared to IMPT plans. In the PAT plans, integral dose was significantly reduced by 18% relative to IMPT plans and by 54% relative to VMAT plans. PAT decreased the mean dose to numerous organs-at-risk (OARs), further reducing NTCPs. The ΔNTCP for PAT relative to VMAT passed the NIPP thresholds for 32 out of the 42 patients treated with VMAT, resulting in 180 patients (81%) of the complete cohort qualifying for protons.

CONCLUSION

PAT outperforms IMPT and VMAT, leading to a further reduction of NTCP-values and higher ΔNTCP-values, significantly increasing the percentage of OPC patients selected for proton therapy.

Effect of prophylactic tube feeding in head and neck cancer patients with high Mallampati score undergoing definitive concurrent chemoradiotherapy

PURPOSE

There is no consensus on the selection of appropriate prophylactic tube feeding in patients with head and neck squamous cell carcinoma (HNSCC) undergoing concurrent chemoradiotherapy (CCRT). This study aimed to evaluate the effect of prophylactic tube feeding in patients with HNSCC who presented with a high Mallampati score and underwent CCRT.

METHODS

We prospectively enrolled 185 consecutive patients with stage II to IVa HNSCC and a pre-treatment Mallampati score of 3 or 4 who received CCRT between August 2017 and December 2018 with follow-up data collected retrospectively. Patients were divided to either with or without prophylactic tube feeding group for comparison of treatment tolerance, toxicities, and quality of life(QOL). Propensity score matching (PSM) was used to achieve balanced covariates across the two groups.

RESULTS

Of the cohort, 52 (28.1%) and 133 (71.9%) patients were allocated to the prophylactic and non-prophylactic tube feeding groups, respectively. Before and after PSM, patients in the tube feeding group had a significantly lower incidence of incomplete radiotherapy, incompletion of chemotherapy, emergency room visits, and grade 3 or higher infection, and improved symptoms of quality of life after CCRT than those in the non-tube feeding group.

CONCLUSION

Prophylactic tube feeding was associated with better treatment tolerance, safety profiles, and quality of life in patients with HNSCC and high Mallampati scores who underwent CCRT. Therefore, Mallampati score might serve as a clinical tool for proactive selection of patients receiving prophylactic tube feeding in HNSCC patients upon receiving CCRT.

Cluster-Based Toxicity Estimation of Osteoradionecrosis via Unsupervised Machine Learning: Moving Beyond Single Dose-Parameter Normal Tissue Complication Probability by Using Whole Dose-Volume Histograms for Cohort Risk Stratification

Purpose

Given the limitations of extant models for normal tissue complication probability estimation for osteoradionecrosis (ORN) of the mandible, the purpose of this study was to enrich statistical inference by exploiting structural properties of data and provide a clinically reliable model for ORN risk evaluation through an unsupervised-learning analysis.

Materials and Methods

The analysis was conducted on retrospective data of 1,259 head and neck cancer (HNC) patients treated at the University of Texas MD Anderson Cancer Center between 2005 and 2015. The (structural) clusters of mandibular dose-volume histograms (DVHs) were identified through the K-means clustering method. A soft-margin support vector machine (SVM) was used to determine the cluster borders and partition the dose-volume space. The risk of ORN for each dose-volume region was calculated based on the clinical risk factors and incidence rates.

Results

The K-means clustering method identified six clusters among the DVHs. Based on the first five clusters, the dose-volume space was partitioned almost perfectly by the soft-margin SVM into distinct regions with different risk indices. The sixth cluster overlapped the others entirely; the region of this cluster was determined by its envelops. These regions and the associated risk indices provide a range of constraints for dose optimization under different risk levels.

Conclusion

This study presents an unsupervised-learning analysis of a large-scale data set to evaluate the risk of mandibular ORN among HNC patients. The results provide a visual risk-assessment tool (based on the whole DVH) and a spectrum of dose constraints for radiation planning.

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.

Risk Factors for Feeding Tube Dependency in Patients Undergoing Function Preservation Surgery for Advanced-Stage Laryngohypopharyngeal Cancer

Dysphagia and feeding tube dependency commonly occur in patients with laryngeal or hypopharyngeal cancer (LHC) during and after treatment, often leading to poor functional outcomes. Therefore, we examined the factors related to feeding tube dependency among advanced-stage LHC patients undergoing curative surgery. This study included 69 consecutive patients who underwent conservative surgery for previously untreated, advanced-stage LHC (squamous cell carcinoma) between 2006 and 2016. Persistent feeding tube dependency was defined as 1 year or more after treatment completion. Binary logistic regression analysis was used to determine the factors associated with reactive prolonged and persistent feeding tube dependency. Cox proportional hazard regression analysis was used to determine the association between feeding tube dependency and survival. None of the study patients had a prophylactic feeding tube, but 15 (21.7%) patients had reactive feeding tube placement for 3 months or more. A total of 9 (13.0%) patients had persistent feeding tube dependency. Univariate analysis showed that age, tracheostomy, and common terminology criteria for adverse events (CTCAE) ≥ 3 were significantly associated with reactive prolonged and persistent feeding tube dependency (all P < 0.05). In the multivariate analysis, advanced age and CTCAE ≥ 3 remained the independent factors of reactive prolonged and persistent feeding tube dependency (all P < 0.05). Feeding tube dependency was not associated with overall survival or disease-free survival (P > 0.1). Feeding tube dependency might be related to clinical factors, such as age and severe adverse events, in the patients undergoing function-preserving surgery for advanced-stage LHC.

Treating Head and Neck Cancer in the Age of Immunotherapy: A 2023 Update

Most patients diagnosed with head and neck squamous cell carcinoma (HNSCC) will present with locally advanced disease, requiring multimodality therapy. While this approach has a curative intent, a significant subset of these patients will develop locoregional failure and/or distant metastases. The prognosis of these patients is poor, and therapeutic options other than palliative chemotherapy are urgently needed. Epidermal growth factor receptor (EGFR) overexpression is an important factor in the pathogenesis of HNSCC, and a decade ago, the EGFR targeting monoclonal antibody cetuximab was approved for the treatment of late-stage HNSCC in different settings. In 2016, the anti-programmed death-1 (PD-1) immune checkpoint inhibitors nivolumab and pembrolizumab were both approved for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy, and in 2019, pembrolizumab was approved for first-line treatment (either as monotherapy in PD-L1 expressing tumors, or in combination with chemotherapy). Currently, trials are ongoing to include immune checkpoint inhibition in the (neo)adjuvant treatment of HNSCC as well as in novel combinations with other drugs in the recurrent/metastatic setting to improve response rates and survival and help overcome resistance mechanisms to immune checkpoint blockade. This article provides a comprehensive review of the management of head and neck cancers in the current era of immunotherapy.

Open Source Repository and Online Calculator of Prediction Models for Diagnosis and Prognosis in Oncology

(1) Background: The main aim was to develop a prototype application that would serve as an open-source repository for a curated subset of predictive and prognostic models regarding oncology, and provide a user-friendly interface for the included models to allow online calculation. The focus of the application is on providing physicians and health professionals with patient-specific information regarding treatment plans, survival rates, and side effects for different expected treatments. (2) Methods: The primarily used models were the ones developed by our research group in the past. This selection was completed by a number of models, addressing the same cancer types but focusing on other outcomes that were selected based on a literature search in PubMed and Medline databases. All selected models were publicly available and had been validated TRIPOD (Transparent Reporting of studies on prediction models for Individual Prognosis Or Diagnosis) type 3 or 2b. (3) Results: The open source repository currently incorporates 18 models from different research groups, evaluated on datasets from different countries. Model types included logistic regression, Cox regression, and recursive partition analysis (decision trees). (4) Conclusions: An application was developed to enable physicians to complement their clinical judgment with user-friendly patient-specific predictions using models that have received internal/external validation. Additionally, this platform enables researchers to display their work, enhancing the use and exposure of their models.

Impact of dosimetric factors on long-term percutaneous enteral gastrostomy (PEG) tube dependence in head and neck cancer patients after (chemo)radiotherapy-results from a prospective randomized trial

Purpose/objective

To analyze dose–volume histogram (DVH)-derived data on the exposure of organs at risk with impact on long-term percutaneous enteral gastrostomy (PEG) tube dependence in head and neck cancer patients at 6 and 12 months after definitive or adjuvant (chemo)radiotherapy.

Materials and methods

Sixty-one patients were prospectively treated with (chemo)radiotherapy. Prophylactic or reactive gastrostomy tube placement was performed in 41 (67.2%) patients. Dose–volume histogram parameters were obtained for the swallowing apparatus.

Results

Median follow-up time was 25 (2–34) months. Overall survival was shorter in patients with inlying PEG tubes at 6 and 12 months (log rank p = 0.038 and p = 0.017) after therapy completion. The estimated median time of tube dependency was 6 (95% confidence interval: 2–14) months. After 6 months, 46.5% of patients were tube dependent. After 12 months, this estimated proportion fell to 31.5%. For both time points, the volume to the larynx (in %) receiving at least 50 Gy (larynx V50Gy) exceeding 53% was predictive for long-term tube feeding (6 months: p = 0.041 and 12 months: p = 0.042) being an independent predictor during multivariable analysis. There was no clinical feature influencing tube dependence after 12 months.

Conclusion

Long-term gastrostomy dependence was found to be strongly associated with an exposure of laryngeal structures (specifically, V50Gy ≥ 53%) during radiotherapy. Consequently, the avoidance of supraglottic as well as glottic structures is warranted.

Association between radiation dose to organs at risk and acute patient reported outcome during radiation treatment for head and neck cancers

BACKGROUND

Associations between patient-reported outcomes and dose to organs at risk (OARs) may promote management and guide future investigations.

METHODS

We retrospectively evaluated PROs and OAR dose in head and neck (H&N) cancer.

RESULTS

In 169 patients, we identified weak associations between: "Difficulty swallowing/chewing" and increased mean RT dose to the oral cavity, larynx, pharyngeal constrictor muscles (PCM) and contralateral parotid; "choking/coughing" and larynx mean dose; "problems with mucus in mouth and throat" and oral cavity, contralateral parotid mean dose and parotid V30, contralateral submandibular gland and PCM mean dose; "difficulty with voice/speech" and oral cavity, contralateral parotid, contralateral submandibular gland and larynx mean dose; and "dry mouth" and ipsilateral submandibular gland, oral cavity and PCM mean dose.

CONCLUSION

We identified weak associations between PRO and dose to OARs-these data can guide on treatment management, patient counseling, and serve as a baseline for future investigations.

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.

Hypofractionated radiotherapy combined with targeted therapy or immunotherapy: Dutch survey on current practice, knowledge and challenges

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Radiotherapy referral during targeted therapy or immunotherapy occurs regularly.

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There is a knowledge gap regarding the implications of combined therapy.

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There is no consensus on expected toxicity of combined therapy.

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Multidisciplinary protocols regarding combined therapy are often not available.

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The application of radiotherapy treatment adaptations varies widely when combined with different systemic treatments.

Introduction

With the introduction of tyrosine kinase inhibitors and systemic antibodies, including immune checkpoint inhibitors, the survival of advanced-stage cancer patients has improved for many tumor types. These patients are increasingly referred for radiotherapy, but it is unclear whether radiotherapy combined with these drugs is safe. No international guidelines exist on whether or how to combine these drugs with radiotherapy. Therefore, we investigated the current clinical practice in the Netherlands regarding hypofractionated radiotherapy in patients using targeted drugs and immunotherapy.

Materials and methods

We sent a survey to all 21 Dutch radiotherapy institutes. Dedicated radiation oncologists, medical oncologists and pulmonologists were asked to fill out the survey. The questions explored their familiarity with the combination of targeted drugs and immunotherapy with radiotherapy, the encountered clinical difficulties and factors influencing treatment decisions.

Results

The survey was filled out by 54 respondents from 19 different institutes. The median annual number of patients per radiation oncologist referred for radiotherapy when using targeted drugs or immunotherapy was 10 and 15, respectively. Despite this high number, only 11% of the radiation oncologists stated that they had sufficient information (resources) for adequate treatment decision making. Among all physicians, 44% stated that there was insufficient knowledge within their institute regarding this topic. Only 17% stated that there was a multidisciplinary protocol available. The application of radiotherapy treatment adaptations (technique, dose, fractionation, field size) varied widely. Generally, there seemed to be no consensus regarding the expected toxicity of combined drug-radiotherapy treatments and the expected risk of tumor flare upon temporary drug discontinuation.

Conclusion

There is no consensus amongst involved medical specialties on expected toxicity. Consequently, it is necessary to perform clinical studies examining the safety of combined drug-radiotherapy treatments, to add radiotherapy to phase I-III clinical trials for new drugs and to incorporate outcomes into multidisciplinary, evidence-based guidelines.

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.

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.

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.

Analysis of acute-phase toxicities of intensity-modulated proton therapy using a model-based approach in pharyngeal cancer patients

Pharyngeal cancer patients treated with intensity-modulated proton therapy (IMPT) using a model-based approach were retrospectively reviewed, and acute toxicities were analyzed. From June 2016 to March 2019, 15 pharyngeal (7 naso-, 5 oro- and 3 hypo-pharyngeal) cancer patients received IMPT with robust optimization. Simulation plans for IMPT and intensity-modulated X-ray therapy (IMXT) were generated before treatment. We also reviewed 127 pharyngeal cancer patients with IMXT in the same treatment period. In the simulation planning comparison, all of the normal-tissue complication probability values for dysphagia, dysgeusia, tube-feeding dependence and xerostomia were lower for IMPT than for IMXT in the 15 patients. After completing IMPT, 13 patients completed the evaluation, and 12 of these patients had a complete response. The proportions of patients who experienced grade 2 or worse acute toxicities in the IMPT and IMXT cohorts were 21.4 and 56.5% for dysphagia (P < 0.05), 46.7 and 76.3% for dysgeusia (P < 0.05), 73.3 and 62.8% for xerostomia (P = 0.43), 73.3 and 90.6% for mucositis (P = 0.08) and 66.7 and 76.4% for dermatitis (P = 0.42), respectively. Multivariate analysis revealed that IMPT was independently associated with a lower rate of grade 2 or worse dysphagia and dysgeusia. After propensity score matching, 12 pairs of IMPT and IMXT patients were selected. Dysphagia was also statistically lower in IMPT than in IMXT (P < 0.05). IMPT using a model-based approach may have clinical benefits for acute dysphagia.

Model-based comparison of organ at risk protection between VMAT and robustly optimised IMPT plans

The comparison between intensity-modulated proton therapy (IMPT) and volume-modulated arc therapy (VMAT) plans, based on models of normal tissue complication probabilities (NTCP), can support the choice of radiation modality. IMPT irradiation plans for 50 patients with head and neck tumours originally treated with photon therapy have been robustly optimised against density and setup uncertainties. The dose distribution has been calculated with a Monte Carlo (MC) algorithm. The comparison of the plans was based on dose-volume parameters in organs at risk (OARs) and NTCP-calculations for xerostomia, sticky saliva, dysphagia and tube feeding using Langendijk's model-based approach. While the dose distribution in the target volumes is similar, the IMPT plans show better protection of OARs. Therefore, it is not the high dose confirmation that constitutes the advantage of protons, but it is the reduction of the mid-to-low dose levels compared to photons. This work investigates to what extent the advantages of proton radiation are beneficial for the patient's post-therapeutic quality of life (QoL). As a result, approximately one third of the patients examined benefit significantly from proton therapy with regard to possible late side effects. Clinical data is needed to confirm the model-based calculations.

Early MRI Blood Volume Changes in Constrictor Muscles Correlate With Postradiation Dysphagia

PURPOSE

Predicting individual patient sensitivity to radiation therapy (RT) for tumor control or normal tissue toxicity is necessary to individualize treatment planning. In head and neck cancer, radiation doses are limited by many nearby critical structures, including structures involved in swallowing. Previous efforts showed that imaging parameters correlate with RT dose; here, we investigate the role of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) blood volume (BV) changes in predicting dysphagia.

METHODS AND MATERIALS

This study included 32 patients with locally advanced oropharyngeal squamous cell carcinoma treated with definitive chemoradiation on an institutional protocol incorporating baseline and early midtreatment DCE-MRI. BV maps of the pharyngeal constrictor muscles (PCM) were created, and BV increases midtreatment were correlated with the following parameters at 3 and 12 months post-RT: RT dose, Dynamic Imaging Grade of Swallowing Toxicity swallow score, aspiration frequency, European Organisation for Research and Treatment of Cancer HN35 patient-reported outcomes, physician-reported dysphagia, and feeding tube (FT) dependence.

RESULTS

The mean BV to the PCMs increased from baseline to fraction 10, which was significant for the superior PCM (P = .006) and middle PCM (P < .001), with a trend in the inferior PCM where lower mean doses were seen (P = .077). The factors associated with FT dependence at 3 months included BV increases in the total PCM (correlation, 0.48; P = .006) and middle PCM (correlation, 0.50; P = .004). A post-RT increase in aspiration was associated with a BV increase in the superior PCM (correlation, 0.44; P = .013),and the increase in the total PCMs was marginally significant (correlation, 0.34; P = .06). The best-performing models of FT dependence (area under the receiver operating curve [AUC] = 0.84) and aspiration increases (AUC = 0.78) included BV increases as well as a mean RT dose to middle PCM.

CONCLUSIONS

Our results suggest that midtreatment BV increases derived from DCE-MRI are an early predictor of dysphagia. Further investigation of these promising imaging markers to assess individual patient sensitivity to treatment and the patient's subsequent risk of toxicities is warranted to improve personalization of RT planning.

[Late toxicity following primary conservative treatment : Dysphagia and xerostomia]

Dysphagia and xerostomia are still among the most important acute and late side effects of radiotherapy. Technical developments over the past two decades have led to improved diagnostics and recognition as well as understanding of the causes of these side effects. Based on these findings and advances in both treatment planning and irradiation techniques, the incidence and severity of treatment-associated radiogenic late sequelae could be clearly reduced by the use of intensity-modulated radiotherapy (IMRT), which could contribute to marked long-term improvements in the quality of life in patients with head and neck cancer. Highly conformal techniques, such as proton therapy have the potential to further reduce treatment-associated side effects in head and neck oncology and are currently being prospectively tested within clinical trial protocols at several centers.

Head and neck IMPT probabilistic dose accumulation: Feasibility of a 2 mm setup uncertainty setting

OBJECTIVE

To establish optimal robust optimization uncertainty settings for clinical head and neck cancer (HNC) patients undergoing 3D image-guided pencil beam scanning (PBS) proton therapy.

METHODS

We analyzed ten consecutive HNC patients treated with 70 and 54.25 Gy_RBE to the primary and prophylactic clinical target volumes (CTV) respectively using intensity-modulated proton therapy (IMPT). Clinical plans were generated using robust optimization with 5 mm/3% setup/range uncertainties (RayStation v6.1). Additional plans were created for 4, 3, 2 and 1 mm setup and 3% range uncertainty and for 3 mm setup and 3%, 2% and 1% range uncertainty. Systematic and random error distributions were determined for setup and range uncertainties based on our quality assurance program. From these, 25 treatment scenarios were sampled for each plan, each consisting of a systematic setup and range error and daily random setup errors. Fraction doses were calculated on the weekly verification CT closest to the date of treatment as this was considered representative of the daily patient anatomy.

RESULTS

Plans with a 2 mm/3% setup/range uncertainty setting adequately covered the primary and prophylactic CTV (V₉₅ ≥ 99% in 98.8% and 90.8% of the treatment scenarios respectively). The average organ-at-risk dose decreased with 1.1 Gy_RBE/mm setup uncertainty reduction and 0.5 Gy_RBE/1% range uncertainty reduction. Normal tissue complication probabilities decreased by 2.0%/mm setup uncertainty reduction and by 0.9%/1% range uncertainty reduction.

CONCLUSION

The results of this study indicate that margin reduction below 3 mm/3% is possible but requires a larger cohort to substantiate clinical introduction.

Risk Factors for Laryngectomy for Dysfunctional Larynx After Organ Preservation Protocols: A Case-Control Analysis

Objective

(1) To identify factors associated with severe dysfunctional larynx leading to total laryngectomy after curative treatment of head and neck squamous cell carcinoma and (2) to describe swallowing and voice outcomes.

Study Design

Retrospective single-institution case-control study.

Setting

Tertiary care referral center.

Methods

A 10-year chart review was performed for patients who had previously undergone radiation or chemoradiation for head and neck mucosal squamous cell carcinoma and planned to undergo total laryngectomy for dysfunctional larynx, as well as a control group of matched patients. Controls were patients who had undergone radiation or chemoradiation for mucosal squamous cell carcinoma but did not have severe dysfunction warranting laryngectomy; these were matched to cases by tumor subsite, T stage, and time from last treatment to video swallow study. Main outcomes assessed were postoperative diet, alaryngeal voice, pharyngeal dilations, and complications.

Results

Twenty-six patients were scheduled for laryngectomy for dysfunctional larynx, of which 23 underwent surgery. Originally treated tumor subsites included the larynx, oropharynx, hypopharynx, oral cavity, and a tumor of unknown origin. The median time from end of cancer treatment to laryngectomy was 11.5 years. All cases were feeding tube or tracheostomy dependent or both prior to laryngectomy. As compared with matched controls, cases were significantly less likely to have undergone IMRT (intensity-modified radiotherapy) and more likely to have pulmonary comorbidities. Eighty-nine percent of cases with follow-up achieved functional alaryngeal voice, and all were able to have oral intake.

Conclusion

Non-IMRT approaches and pulmonary comorbidities are associated with laryngectomy for dysfunction after radiation or chemoradiation.

Precision toxicity correlates of tumor spatial proximity to organs at risk in cancer patients receiving intensity-modulated radiotherapy

PURPOSE

Using a 200 Head and Neck cancer (HNC) patient cohort, we employ patient similarity based on tumor location, volume, and proximity to organs at risk to predict radiation-associated dysphagia (RAD) in a new patient receiving intensity modulated radiation therapy (IMRT).

MATERIAL AND METHODS

All patients were treated using curative-intent IMRT. Anatomical features were extracted from contrast-enhanced tomography scans acquired pre-treatment. Patient similarity was computed using a topological similarity measure, which allowed for the prediction of normal tissues' mean doses. We performed feature selection and clustering, and used the resulting groups of patients to forecast RAD. We used Logistic Regression (LG) cross-validation to assess the potential toxicity risk of these groupings.

RESULTS

Out of 200 patients, 34 patients were recorded as having RAD. Patient clusters were significantly correlated with RAD (p < .0001). The area under the receiver-operator curve (AUC) using pre-established, baseline features gave a predictive accuracy of 0.79, while the addition of our cluster labels improved accuracy to 0.84.

CONCLUSION

Our results show that spatial information available pre-treatment can be used to robustly identify groups of RAD high-risk patients. We identify feature sets that considerably improve toxicity risk prediction beyond what is possible using baseline features. Our results also suggest that similarity-based predicted mean doses to organs can be used as valid predictors of risk to organs.

Clinical and dosimetric risk stratification for patients at high-risk of feeding tube use during definitive IMRT for head and neck cancer

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Understanding feeding tube risk is critical to optimal weight maintenance during radiotherapy.

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T-stage, Level II lymphadenopathy risk stratify feeding tube use into 4 groups.

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The addition of cervical oesophagus dose can further refine these risk stratified groups.

Introduction

To identify organs to which dose limitation using intensity modulated radiotherapy (IMRT) can potentially modify the incidence and duration of feeding tube use, during and immediately following therapy for head and neck cancer.

Materials and methods

One hundred and fourteen patients treated with definitive IMRT (± concurrent chemotherapy) head and neck mucosal cancers were included. Patients received a prophylactic feeding tube and followed up by a dietician for at least eight weeks post-radiotherapy. Salivary and swallowing organs were delineated for each patient. Tumour and dosimetric variables were recorded for all patients and analysed for incidence and duration of feeding tube use for at least 25% of dietary requirements.

Results

Multivariate analysis showed T-classification ≥3 and level II lymphadenopathy as independent significant predictors of incidence and duration of feeding tube use in oral cavity, pharyngeal and supraglottic primaries. Mean dose deposited in the cervical oesophagus over 36Gy further increased the incidence and duration of feeding tube use. Mean dose deposited in the base of tongue and superior pharyngeal constrictor muscles affected incidence and duration of feeding tube use, respectively.

Discussion

In patients treated with definitive IMRT, T-classification and Level II lymphadenopathy, combined with a mean cervical oesophagus dose over 36Gy can a stratify patients into eight distinct risk groups for using feeding tubes for at least 25% of their dietary requirements.

Dosimetric factors associated with long-term patient-reported outcomes after definitive radiotherapy of patients with head and neck cancer

Background

The aim of this study was to explore the relationships between dosimetric parameters of organs at risk and patient-reported outcomes (PRO) after radiotherapy of patients with head and neck cancer.

Methods

PRO data of 53 patients with head and neck cancer treated with radiotherapy were prospectively collected. These data concerned health-related quality of life (HRQOL) and were collected using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30) and head and neck cancer module (QLQ-H&N35). Patients were divided into “severe-deterioration” and “mild-deterioration” groups on the basis of degree of deterioration HRQOL > 6 months after completing treatment. The relationships between HRQOL deteriorations and patient-related or dosimetry-related factors were evaluated. P < 0.0013 according to Bonferroni correction was considered to denote statistical significance.

Results

Regarding “trouble with social eating (HNSO)” and “coughing (HNCO),” there were significant differences between the severe-deterioration and mild-deterioration groups in mean dosages to the superior pharyngeal constrictor muscle (SPC) (HNSO: 62.5 Gy vs 54.2 Gy; p = 0.00029, and HNCO: 61.5 Gy vs 54.1 Gy; p = 0.0012) and parotid gland (HNSO: 24.1 Gy vs 20.5 Gy; p = 0.000056, and HNCO: 24.2 Gy vs 20.3 Gy; p = 0.00043). Regarding “nausea and vomiting,” there was a significant difference between the two groups in the mean dosage to the middle pharyngeal constrictor muscle (MPC: 61.9 Gy vs. 58.4Gy; P = 0.00059).

Conclusions

We found that dosages to the SPC and parotid gland were associated with severe deterioration in HRQOL attributable to difficulty in HNSO and HNCO, whereas dosage to the MPC was associated with severe deterioration attributable to nausea and vomiting.

The changing landscape of head and neck cancer radiotherapy patients: is high-risk, prolonged feeding tube use indicative of on-treatment weight loss?

INTRODUCTION

Precision radiotherapy relies heavily on optimal weight management. Our group previously developed a risk stratification model for patients at risk of prolonged feeding tube (FT) intervention. The study objective was to assess on-treatment weight loss according to stratified risk of prolonged FT use.

METHODS

One hundred and one (n = 101) definitive head and neck radiotherapy patients were included in this study. Patients were stratified into high risk (HRi: T-classification ≥ 3 with level 2 Nodal disease), high-intermediate risk (HIRi: T-classification ≥ 3 without level 2 Nodes) and low-intermediate risk (LIRi: T-classification < 3 with level 2 Nodes) of prolonged FT use. Demographic variables and on-treatment weight loss were evaluated according to risk status.

RESULTS

Oropharyngeal carcinoma (OPC) was present in a larger proportion in the LIRi cohort (HRi: 71%, HIRi: 52%, LIRi: 81%, P = 0.008). LIRi patients were more likely to have human papilloma virus (HPV)-associated disease (88%, P = 0.001). Never/minimal smoking (P = 0.003), good performance status (P < 0.001), healthy BMI (P = 0.050) and no pre-existing dysphagia (P < 0.001) were predominant within the LIRi prognostic group. LIRi patients lost significantly more weight in total (HRi = 4.8% vs. LIRi = 8.2%, P = 0.002; HIRi = 5.2% vs. LIRi = 8.2%, P = 0.006) and when using a FT (HRi = 4.6% vs. LIRi = 8.8%, P < 0.001; HIRi = 5.3% vs. LIRi = 8.8%, P = 0.002).

CONCLUSIONS

Patients identified as low-intermediate risk of prolonged, ≥25% FT use report significantly increased weight loss compared with patients at higher risk of FT use. This cohort is typical of the increasing number of patients presenting with HPV-associated OPC. Results of this study suggest we should closely observe such patients throughout treatment, to ensure optimal weight maintenance, facilitating precision radiotherapy.

Deintensification of Adjuvant Treatment After Transoral Surgery in Patients With Human Papillomavirus-Positive Oropharyngeal Cancer: The Conception of the PATHOS Study and Its Development

PATHOS is a phase II/III randomized controlled trial (RCT) of risk-stratified, reduced intensity adjuvant treatment in patients undergoing transoral surgery (TOS) for human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC). The study opened in the UK in October 2015 and, after successful recruitment into the phase II, transitioned into phase III in the autumn of 2018. PATHOS aims to establish whether the de-intensification of adjuvant treatment in patients with favorable prognosis HPV-positive OPSCC will confer improved swallowing outcomes, whilst maintaining high rates of cure. In this article, we will outline the rationale for the study and how it aims to answer fundamentally important questions about the safety, effectiveness and functional outcomes of minimally invasive TOS techniques followed by adjuvant radiotherapy (RT) or chemo-radiotherapy (CRT) in this patient population.

Differences between planned and delivered dose for head and neck cancer, and their consequences for normal tissue complication probability and treatment adaptation

BACKGROUND AND PURPOSE

Anatomical changes induce differences between planned and delivered dose. Adaptive radiotherapy (ART) may reduce these differences but the optimal implementation is insufficiently clear. The aims of this study were to quantify the difference between planned and delivered dose in HNC patients, assess the consequential difference in normal tissue complication probability (ΔNTCP) and to explore the value of ΔNTCP as an objective selection strategy for ART.

MATERIALS AND METHODS

For 52 patients, daily doses were accumulated to estimate the delivered dose. The difference from planned dose was analyzed for CTVs and 9 organs-at-risk (OAR). ΔNTCP was calculated for xerostomia, dysphagia, parotid gland dysfunction and tube feeding dependency at 6 months. ART was deemed necessary if ΔNTCP was >5%. The positive predicted value (PPV) was calculated for identification of ART-patients by clinical judgement, and ΔNTCP at fraction 10 and 15.

RESULTS

ΔNTCP >5% was seen five times for dysphagia and twice for the other toxicities. Only 5/9 patients with any ΔNTCP >5% clinically received ART, although ART had been done for 13/52 patients (PPV: 0.38). PPV was 0.86 and 0.75 for accumulated dose at fraction 10 and 15, respectively, using a ΔNTCP cut-off for the allocation of ART of 5%. Using other ΔNTCP cut-offs did not substantially improve PPV. With this cut-off the negative predictive value was 0.93 for ΔNTCP method of fraction 10 and fraction 15, and 0.90 for clinical judgement.

CONCLUSION

To identify patients accurately for ART, NTCP calculations based on the dose differences between planned and delivered dose at fraction 10 are superior to clinical judgement.

Chronic radiation-associated dysphagia in oropharyngeal cancer survivors: Towards age-adjusted dose constraints for deglutitive muscles

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Age at treatment for OPSCC is a strong predictor of chronic radiation associated dysphagia (RAD).

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For swallowing regions of interest (ROIs), dose to ROI and age impact patients’ risk of chronic RAD.

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For patients at high risk for RAD more intense prophylactic swallowing therapies may be warranted.

Objectives

We sought to model chronic radiation-associated dysphagia (RAD) in patients given intensity-modulated radiation therapy (IMRT) for oropharyngeal squamous cell cancer (OPSCC) as a function of age and dose to non-target swallowing muscles.

Methods

We reviewed 300 patients with T1-T4 N0-3 M0 OPSCC given definitive IMRT with concurrent chemotherapy. Chronic RAD was defined as aspiration or stricture on videoflouroscopy/endoscopy, gastrostomy tube, or aspiration pneumonia at ≥12 months after IMRT. Doses to autosegmented regions of interest (ROIs; inferior, middle and superior constrictors, anterior and posterior digastrics, mylo/geniohyoid complex, intrinsic tongue, and gengioglossus) were obtained from DICOM-RT plans and dose-volume histograms. The probability of chronic RAD as a function of mean ROI dose, stratified by age (<50, 50–59, 60–69, or ≥70 years), was estimated with logistic probability models and subsequent unsupervised nonlinear curves.

Results

Chronic RAD was observed in 34 patients (11%). Age was a significant correlate of chronic RAD, both independently and with dose for all muscle groups examined. Distinct muscle-specific dose–response profiles were observed as a function of age (e.g., 5% of patients in their 50 s [but 20% of those 70 + ] who received 60 Gy to the superior constrictor had chronic RAD). This effect was stable across all observed muscle ROIs, with a false discovery rate-corrected p < 0.05, for all dose/muscle/age models, suggesting that including age as a covariate improves modeling of chronic RAD.

Conclusions

Age at treatment moderates the probability of chronic RAD after chemo-IMRT for OPSCC, with aging muscles showing lower dose thresholds. Uniform dose constraints may not predict toxicity in older patients.

A prospective longitudinal assessment of MRI signal intensity kinetics of non-target muscles in patients with advanced stage oropharyngeal cancer in relationship to radiotherapy dose and post-treatment radiation-associated dysphagia: Preliminary findings from a randomized trial

PURPOSE

To assess quantitative signal intensity (SI) kinetics obtained from serial MRI of swallowing muscles as a potential imaging biomarker of radiation-induced dysphagia in oropharyngeal cancer (OPC) patients receiving radiotherapy (RT).

METHODS

Patients were enrolled under an IRB approved Phase II/III randomized trial. Patients underwent serial MRIs at pre-, mid-, and post-RT. Normalized T1, T1+ contrast (T1 + C), and T2 SI for swallowing muscle volumes-of-interest (VOIs) were collected and delta SI changes (Δ) were calculated. Mid- and post-RT SI relative to baseline were assessed and correlations between radiation dose and percent change in SI were calculated. Independent samples' t-tests were used to compare the percent change of SI between patients divided into two groups based on dysphagia status post-RT.

RESULTS

Forty-six patients with stage III/IV HPV+ OPC were included in this study. Relative to baseline, mean T2 and T1 + C SIs for middle pharyngeal constrictor were both significantly higher at mid- and post-RT (p < 0.004 for all). Superior pharyngeal constrictor also showed a significant increase in T1 + C SI at mid-RT (p = 0.0004). Additional muscle VOIs showed significant changes post-RT, but not earlier at mid-RT. Both mid- and post-RT doses were significantly correlated with the percent change of normalized T2 and T1 + C SI for examined muscle VOIs (p < 0.002). Mean percent changes of normalized T2 SI at mid-RT relative to baseline for all muscle VOIs were significantly higher in patients who developed grade ≥2 dysphagia relative to patients with no/mild dysphasia (mean Δ%: 8.2% vs 1.9%; respectively, p = 0.002). However, at post-RT, these changes were only significant in T1 SI (11.2% vs -1.3%; p < 0.0001).

CONCLUSION

Signal intensity kinetics of radiation injury can be broadly correlated with the functional muscular defect. Serial MRI during the course of RT may provide an opportunity to quantitatively track muscular pathology for subclinical detection of patients at high risk to develop dysphagia.

Knowledge-based dose prediction models for head and neck cancer are strongly affected by interorgan dependency and dataset inconsistency

PURPOSE

The goal of this study was to generate a large treatment plan database for head and neck (H&N) cancer patients that can be considered as the gold standard to train and validate models for knowledge-based (KB) treatment planning and QA. With this dataset, the intrinsic prediction performance, the effect of interorgan dependency, and the impact of dataset inconsistency was investigated for an existing treatment planning QA model.

METHODS

The CT scans of 108 previously treated oropharyngeal patients were used to establish the plan database. For each patient, 15 Pareto optimal treatment plans with different planning priorities for the parotid glands were generated with fully automatic multicriterial treatment planning (1620 plans in total). For each of the 15 sets of plans in the database, a KB model was trained with 54 patients and validated on the other 54 by comparing the predictions with the achieved doses. The dose prediction accuracy (predicted-achieved) of the KB models was assessed and compared among the different models to characterize the intrinsic performance and effect of interorgan dependency. In addition, the effect of dataset inconsistency with respect to planning prioritizations was investigated by mixing plans with different prioritizations, for the training, the validation dataset, and for both combined.

RESULTS

In the case of a high planning priority, the mean ± SD of the prediction error for the mean dose of the parotid glands was only 0.2 ± 2.2 Gy, but this increased to 1.0 ± 5.0 Gy in the case that the parotid glands had a low planning priority. Dataset inconsistency (in planning priority) led to a large increase in prediction error for the parotid glands (mean ± SD) from 0.2 ± 2.2 Gy to 2.8 ± 3.3 Gy, -3.2 ± 5.0 Gy or -0.6 ± 5.4 Gy, depending on the way the datasets were mixed.

CONCLUSIONS

The generated plan database can be used to validate and characterize KB prediction models for H&N cancer and will be made available upon request. The investigated KB model performed well in case the parotid glands had a high planning priority (little dependence on lower priority OARs), but poorly for organs for which the dose strongly depends on other higher priority OARs. To improve the performance of KB prediction models for H&N cancer, interorgan dependency should be modeled and accounted for. Dataset inconsistency has a large negative impact on the prediction errors of KB models and should be avoided as much as possible.

Clinical Trial Strategies to Compare Protons With Photons

The favorable beam properties of protons can be translated into clinical benefits by target dose escalation to improve local control without enhancing unacceptable radiation toxicity or to spare normal tissues to prevent radiation-induced side effects without jeopardizing local tumor control. For the clinical validation of the added value of protons to improve local control, randomized controlled trials are required. For the clinical validation of the added value of protons to prevent side effects, both model-based validation or randomized controlled trials can be used. Model-based patient selection for proton therapy is crucial, independent of the validation approach. Combining these approaches in rapid learning health care systems is expected to yield the most efficient and scientifically sound way to continuously improve patient selection and the therapeutic window, eventually leading to more cancer survivors with better quality of life.

18F-FDG Metabolic Tumor Volume: Association with Short- and Long-Term Feeding Tube Use in Head and Neck IMRT

The purpose of this study was to investigate whether the metabolic tumor volume (MTV) of head and neck primary tumors may be a significant prognostic factor for feeding tube (FT) use and FT dependence. Seventy-nine patients with evaluable primary tumors, pre-therapy FDG-PET scans, treated with definitive intensity-modulated radiotherapy (IMRT) (± concurrent chemotherapy) for head and neck mucosal cancers were included. MTV was quantified and recorded for the primary lesion using a minimum standardized uptake value (SUV) threshold of 2.0. Patients were recommended prophylactic FT and followed up by a dietician for at least eight weeks of post-radiotherapy. Associations between MTV, dose to swallowing organs at risk, FT use, and FT dependence were analyzed. MTV was positively correlated with gross tumor volume (GTV) (r = 0.7357; p < 0.0001). MTVs larger than 17 cc were associated with higher rates of FT use (87.8% vs. 69.5%, p = 0.0067) and FT dependence at six weeks (76.7% vs. 41.7%, p = 0.0024) and six months (25.0% vs. 8.7%, p = 0.0088). Increasing MTV was associated with increasing mean dose to the oral cavity (p = < 0.0001), tongue base (p = 0.0009), and superior (SPCM) (p = 0.0001) and middle pharyngeal constrictor muscles (MPCM) (p = 0.0005). Increasing MTV was associated with increasing maximum dose to oral cavity (p = 0.0028), tongue base (p = 0.0056), SPCM (p = 0.0037), and MPCM (p = 0.0085). Pre-treatment MTV is a reproducible parameter that can be generated at or prior to a pre-treatment Multidisciplinary Tumor Board and may expedite decisions regarding placement of prophylactic FTs. Prospective evaluation in larger series is required to determine whether MTV is a more useful prognostic variable for FT use than clinical T-classification.

Data Analysis in Radiotherapy Treatments

Radiotherapy is one of the main cancer treatments available today, together with chemotherapy and surgery. Radiotherapy treatments have to be planned for each patient in an individualized manner. The knowledge acquired from one single treatment can be used to improve the treatment planning and outcome of several other patients. In the last years, attention has been drawn to the added value of using data analysis for radiotherapy treatment planning, prediction of treatment outcomes, survival analysis and quality assurance. In this article, existing literature is reviewed.

Assessing Novel Drugs and Radiation Technology in the Chemoradiation of Oropharyngeal Cancer

Integrating immunotherapy, proton therapy and biological dose escalation into the definitive chemoradiation of oropharyngeal cancer poses several challenges. Reliable and reproducible data must be obtained in a timely fashion. However, despite recent international radiotherapy contouring guidelines, controversy persists as to the applicability of such guidelines to all cases. Similarly, a lack of consensus exists concerning both the definition of the organ at risk for oral mucositis and the most appropriate endpoint to measure for this critical toxicity. Finally, the correlation between early markers of efficacy such as complete response on PET CT following treatment and subsequent survival needs elucidation for biological subsets of oropharyngeal cancer.

Prospective in silico study of the feasibility and dosimetric advantages of MRI-guided dose adaptation for human papillomavirus positive oropharyngeal cancer patients compared with standard IMRT

PURPOSE

We aim to determine the feasibility and dosimetric benefits of a novel MRI-guided IMRT dose-adaption strategy for human papillomavirus positive (HPV+) oropharyngeal squamous cell carcinoma (OPC).

MATERIALS/METHODS

Patients with locally advanced HPV+ OPC underwent pre-treatment and in-treatment MRIs every two weeks using RT immobilization setup. For each patient, two IMRT plans were created (i.e. standard and adaptive). The prescription dose for the standard plans was 2.12 Gy/fx for 33 fractions to the initial PTV. For adaptive plans, a new PTVadaptive was generated based on serial MRIs in case of detectable tumor shrinkage. Prescription dose to PTVadaptive was 2.12 Gy/fx to allow for maximum dose to the residual disease. Any previously involved volumes received minimally a floor dose of 50.16 Gy. Uninvolved elective nodal volumes were prescribed 50.16 Gy in 1.52 Gy/fx. Dosimetric parameters of organs at risk (OARs) were recorded for standard vs. adaptive plans. Normal tissue complication probability (NTCP) for toxicity endpoints was calculated using literature-derived multivariate logistic regression models.

RESULTS

Five patients were included in this pilot study, 3 men and 2 women. Median age was 58 years (range 45-69). Three tumors originated at the tonsillar fossa and two at the base of tongue. The average dose to 95% of initial PTV volume was 70.7 Gy (SD,0.3) for standard plans vs. 58.5 Gy (SD,2.0) for adaptive plans. The majority of OARs showed decrease in dosimetric parameters using adaptive plans vs. standard plans, particularly swallowing related structures. The average reduction in the probability of developing dysphagia ≥ grade2, feeding tube persistence at 6-month post-treatment and hypothyroidism at 1-year post-treatment was 11%, 4%, and 5%, respectively. The probability of xerostomia at 6-month was only reduced by 1% for adaptive plans vs. standard IMRT.

CONCLUSION

These in silico results showed that the proposed MRI-guided adaptive approach is technically feasible and advantageous in reducing dose to OARs, especially swallowing musculature.

Proton Therapy for Head and Neck Cancers

Because of its sharp lateral penumbra and steep distal fall-off, proton therapy offers dosimetric advantages over photon therapy. In head and neck cancer, proton therapy has been used for decades in the treatment of skull-base tumors. In recent years the use of proton therapy has been extended to numerous other disease sites, including nasopharynx, oropharynx, nasal cavity and paranasal sinuses, periorbital tumors, skin, and salivary gland, or to reirradiation. The aim of this review is to present the physical properties and dosimetric benefit of proton therapy over advanced photon therapy; to summarize the clinical benefit described for each disease site; and to discuss issues of patient selection and cost-effectiveness.

Pretreatment risk stratification of feeding tube use in patients treated with intensity-modulated radiotherapy for head and neck cancer

BACKGROUND

The purpose of this study was to establish a risk stratification model for feeding tube use in patients who undergo intensity-modulated radiotherapy (IMRT) for head and neck cancers.

METHODS

One hundred thirty-nine patients treated with definitive IMRT (+/- concurrent chemotherapy) for head and neck mucosal cancers were included in this study. Patients were recommended a prophylactic feeding tube and followed up by a dietician for at least 8 weeks postradiotherapy (post-RT). Potential prognostic factors were analyzed for risk and duration of feeding tube use for at least 25% of dietary requirements.

RESULTS

Many variables had significant effects on risk and/or duration of feeding tube use in univariate analyses. Subsequent multivariable analysis showed that T classification ≥3 and level 2 lymphadenopathy were the best independent significant predictors of higher risk and duration of feeding tube use, respectively, in oral cavity, pharyngeal, and supraglottic primaries.

CONCLUSION

In patients treated with definitive IMRT, T classification ≥3 and level 2 lymphadenopathy can potentially stratify patients into 4 risk groups for developing severe dysphagia requiring feeding tube use.