TORPEdO - A Phase III Trial of Intensity-modulated Proton Beam Therapy Versus Intensity-modulated Radiotherapy for Multi-toxicity Reduction in Oropharyngeal Cancer

Global assessment of swallow function (GASF) following VMAT radiotherapy for head and neck squamous cell carcinoma

Aim

This study aimed to conduct a global assessment of swallow function (GASF) using a range of swallow outcome tools, in a cohort of patients pre- and post-treatment with image-guided volumetric modulated arc therapy (VMAT) radiotherapy.

Materials and methods

All patients receiving radical (chemo)radiation for SCC of the larynx, oro-, hypo- or nasopharynx between October 2016 - 2021 were eligible for inclusion.Patients were treated with VMAT radiotherapy according to institutional and national protocols.Patients underwent GASF pre- and 6 months post-treatment. Data were collated from the MD Anderson Dysphagia Inventory (MDADI), the Functional Oral Intake Scale (FOIS), the Performance Status Scale-Head and Neck: Normalcy of Diet scale (PSS-NoD), the 100 ml water swallow test (WST) for capacity and maximal interincisal opening (MIO).

Results

One hundred and seventy-five patients were included. 55.2 % of patients experienced a fall in MDADI-Composite score greater than the published meaningful clinical important difference (MCID).A trend for a decrease in FOIS score reflects a decrease in range of diet textures and increase in reliance on enteral feeding at 6 months post-treatment.Mean PSS-NoD score decreased reflecting increased restriction in diet textures.20 patients' WST capacity improved by the minimal clinically important difference of > 4mls whilst 37 % of patients experienced a decrease in WST capacity of 4mls or more. 12.6 % of patients developed trismus following radiotherapy.

Conclusions

This paper adds new detail to the understanding of the decline in measured eating, drinking and swallowing function that patients treated with VMAT radiotherapyexperience at 6 months post treatment. However, gaps are highlighted in the evidence base in terms of interpretation of swallow outcomes tool scores; future research in HNC should include ongoing discussion and development around robust outcomes tools and data collection.

Clinical advantages of incorporating predicted weekly anatomy in IMPT optimization with reduced setup error

BACKGROUND

In head and neck (H&N) cancer treatment, a conventional setup error (SE) of 3mm is often used in robust optimization (cRO3mm). However, cRO3mm may lead to excessive radiation doses to organs at risk (OARs) and does not purposefully compensate for interfractional anatomy variations.

PURPOSE

This study introduces a method using predicted images from an anatomical model and a reduced 1mm SE uncertainty for robust optimization (aRO1mm), aiming to decrease the dose to OARs without affecting the coverage of the clinical target volume (CTV).

METHODS

This retrospective study involved 10 nasopharynx radiotherapy patients. Validation CT scans (vCT) from treatment weeks 1 to 6 were analyzed. A predictive anatomical model, designed to capture the average anatomical changes over time, provided predicted CT images for weeks 1, 3, and 5. We compared three optimization scenarios: (1) aRO1mm, using three predicted images with 1mm setup shift and 3% range uncertainty, (2) cRO3mm, with a robust 3mm setup shift and 3% range uncertainty, and (3) cRO1mm, a robust 1mm setup shift and 3% range uncertainty. The accumulated dose to CTVs and serial organs was evaluated under these uncertainties, while parallel OARs were assessed using the accumulated nominal dose (without errors).

RESULTS

The accumulated volume receiving 94% of the prescribed dose (V94) for CTVs in cRO3mm exceeded 98%, meeting the clinical goal. For high-risk CTV, the minimum V94 was 96.44% in aRO1mm and 94.05% in cRO1mm. For low-risk CTV, these values were 97.68% in aRO1mm and 97.15% in cRO1mm. When comparing aRO1mm to cRO3mm on OARs, aRO1mm reduced normal tissue complication probability (NTCP) for grade ≥ $\ge$ 2 xerostomia and dysphagia by averages of 3.67% and 1.54%, respectively.

CONCLUSION

aRO1mm lowers the radiation dose to OARs compared to the traditional approach, while maintaining adequate dose coverage on the target area. This method offers an improved strategy for managing uncertainties in radiation therapy planning for H&N cancer, enhancing treatment effectiveness.

The Case for Allowing Proton Beam Therapy on Head and Neck Cooperative Group Studies

This Viewpoint present the case for revisiting the proscription of proton beam therapy in trials of patients with de novo, nonmetastatic head and neck cancer.

Hitting the Target: Developing High-quality Evidence for Proton Beam Therapy Through Randomised Controlled Trials

The National Health Service strategy for the delivery of proton beam therapy (PBT) in the UK provides a unique opportunity to deliver high-quality evidence for PBT through randomised controlled trials (RCTs). We present a summary of three UK PBT RCTs in progress, including consideration of their key design characteristics and outcome assessments, to inform and support future PBT trial development. The first three UK multicentre phase III PBT RCTs (TORPEdO, PARABLE and APPROACH), will compare PBT with photon radiotherapy for oropharyngeal squamous cell carcinoma, breast cancer and oligodendroglioma, respectively. All three studies were designed by multidisciplinary teams, which combined expertise from clinicians, clinical trialists and scientists with strong patient advocacy and guidance from national radiotherapy research networks and international collaborators. Consistent across all three studies is a focus on the reduction of long-term radiotherapy-related toxicities and an evaluation of patient-reported outcomes and health-related quality of life, which will address key uncertainties regarding the clinical benefits of PBT. Innovative translational components will provide insights into mechanisms of toxicity and help to frame the key future research questions regarding PBT. The UK radiotherapy research community is developing and delivering an internationally impactful PBT research portfolio. The combination of data from RCTs with prospectively collected data from a national PBT outcomes registry will provide an innovative, high-quality repository for PBT research and the platform to design and deliver future trials of PBT.

Effect of definitive hypo-fractionated radiotherapy concurrent with weekly cisplatin in locally advanced squamous cell carcinoma of the head and neck

To mitigate the risk of COVID-19 infection in cancer patients, it is recommended to utilize hypo-fractionated treatment schedules that aim to minimize the overall duration of treatment. In this study, we aimed to determine whether hypo-fractionated intensity-modulated radiotherapy (hypo-IMRT) with concurrent chemotherapy was practical, effective, and could achieve acceptable tumor control rates for squamous cell carcinoma of the head and neck (SCCHN). We enrolled 62 patients with high-risk stage II, stage III, and IVA SCCHN who received hypo-IMRT (62.5 Gy in 25 fractions over 5 weeks 2.5Gy/fraction with weekly cisplatin 40 mg/m²). Our primary endpoint was to assess acute toxicity, while our secondary endpoints were late toxicity, loco-regional control, disease-free survival, and overall survival. The percentages of grade 3 acute pain, dermatitis, mucositis, and dysphagia were 71%, 19.4%, 72.6%, and 41.9%, respectively. The rates of late xerostomia, dysphagia, dental complications, grade 3 pain, and grade 3 weight loss were 72.6%, 62.9%, 27.4%, 4.8%, and 4.3%, respectively. At a median follow-up time of 24 months, 2-year loco-regional control and overall survival were 87.1% and 83.9%, respectively. Disease-free survival was 100%, 89.5%, and 69% in stages II, III, and IV%, respectively, with a significant p-value of 0.024. This regimen was effective and relatively safe, with acceptable and tolerable acute and late toxicity. Given the reduced need for hospital visits, hypo-fractionated schedules may represent an alternative treatment during the COVID-19 outbreak.

Proton Beam Radiation Therapy for Oropharyngeal Squamous Cell Carcinoma

Purpose

To discuss the role of proton beam therapy (PBT) in the treatment of patients with oropharyngeal squamous cell carcinoma (OPSCC).

Materials and Methods

A review of the pertinent literature.

Results

Proton beam therapy likely results in reduced acute and late toxicity as compared with intensity-modulated radiation therapy (IMRT). The extent of the reduced toxicity, which may be modest, depends on the endpoint and technical factors such as pencil beam versus passive scattered PBT and adaptive replanning. The disease control rates after PBT are likely similar to those after IMRT.

Conclusion

Proton beam therapy is an attractive option to treat patients with OPSCC. Whether it becomes widely available depends on access.

Planned dose of intensity modulated proton beam therapy versus volumetric modulated arch therapy to tooth-bearing regions

BACKGROUND

Intensity modulated proton beam therapy (IMPT) for head and neck cancer offers dosimetric benefits for the organs at risk when compared to photon-based volumetric modulated arch therapy (VMAT). However, limited data exists about the potential benefits of IMPT for tooth-bearing regions. The aim of this study was to compare the IMPT and VMAT radiation dosimetrics of the tooth-bearing regions in head and neck cancer patients. Also, we aimed to identify prognostic factors for a cumulative radiation dose of ≥40 Gy on the tooth-bearing areas, which is considered the threshold dose for prophylactic dental extractions.

METHODS

A total of 121 head and neck cancer patients were included in this retrospective analysis of prospectively collected data. We compared the average Dmean values of IMPT versus VMAT of multiple tooth-bearing regions in the same patients. Multivariate logistic regression analysis was performed for receiving a cumulative radiation dose of ≥40 Gy to the tooth-bearing regions (primary endpoint) in both VMAT and IMPT.

RESULTS

A lower Dmean was seen after applying IMPT to the tooth-bearing tumour regions (p < 0.001). Regarding VMAT, oral cavity tumours, T3-T4 tumours, molar regions in the mandible, and regions ipsilateral to the tumour were risk factors for receiving a cumulative radiation dose of ≥40 Gy.

CONCLUSIONS

IMPT significantly reduces the radiation dose to the tooth-bearing regions.

Treatment of oropharyngeal squamous cell carcinoma: Is swallowing quality better after TORS or RT?

BACKGROUND AND PURPOSE

To answer an important question regarding the long-term morbidity of two oncological equivalent treatment for oropharyngeal squamous cell carcinoma (OPSCC), namely a comparison of swallowing function results between patients treated with trans-oral robotic surgery (TORS) versus patients treated with radiotherapy (RT).

MATERIALS AND METHODS

Studies included patients with OPSCC treated with TORS or RT. Articles reporting complete data on MD Anderson Dysphagia Inventory (MDADI) and comparing the two treatments (TORS vs RT) were included in the meta-analysis. Swallowing assessed with MDADI was the primary outcome, the evaluation with instrumental methods was the secondary aim.

RESULTS

Included studies provided a total of 196 OPSCC primarily treated with TORS vs 283 OPSCC primarily treated with RT. The mean difference in MDADI score at the longest follow-up was not significantly different between TORS and RT group (mean difference [MD] -0.52; 95% CI -4.53-3.48; p = 0.80). After treatment, mean composite MDADI scores demonstrated a slight impairment in both groups without reaching a statistical difference compared to the baseline status. DIGEST score and Yale score showed a significantly worse function in both treatment groups at 12-month follow-up compared to baseline status.

CONCLUSION

The meta-analysis demonstrates that up-front TORS (+- adjuvant therapy) and up-front RT (+- CT) appear to be equivalent treatments in functional outcomes in T1-T2, N0-2 OPSCC, however, both treatments cause impaired swallowing ability. Clinicians should have a holistic approach and work with patients to develop an individualized nutrition plan and swallowing rehabilitation protocol from diagnosis to post-treatment surveillance.

TORPEdO: A phase III trial of intensity-modulated proton beam therapy versus intensity-modulated radiotherapy for multi-toxicity reduction in oropharyngeal cancer

•There is a lack of prospective level I evidence for the use of PBT for most adult cancers including oropharyngeal squamous cell carcinoma (OPSCC).•TORPEdO is the UK's first PBT clinical trial and aims to determine the benefits of PBT for OPSCC.•Training and support has been provided before and during the trial to reduce variations of contouring and radiotherapy planning.•There is a strong translational component within TORPEdO. Imaging and physics data along with blood, tissue collection will inform future studies in refining patient selection for IMPT.

Toxicity Profiles and Survival Outcomes Among Patients With Nonmetastatic Oropharyngeal Carcinoma Treated With Intensity-Modulated Proton Therapy vs Intensity-Modulated Radiation Therapy

IMPORTANCE

Patients with oropharyngeal carcinoma (OPC) treated with radiotherapy often experience substantial toxic effects, even with modern techniques such as intensity-modulated radiation therapy (IMRT). Intensity-modulated proton therapy (IMPT) has a potential advantage over IMRT due to reduced dose to the surrounding organs at risk; however, data are scarce given the limited availability and use of IMPT.

OBJECTIVE

To compare toxic effects and oncologic outcomes among patients with newly diagnosed nonmetastatic OPC treated with IMPT vs IMRT with or without chemotherapy.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included patients aged 18 years or older with newly diagnosed nonmetastatic OPC who received curative-intent radiotherapy with IMPT or IMRT at a single-institution tertiary academic cancer center from January 1, 2018, to December 31, 2021, with follow-up through December 31, 2021.

EXPOSURES

IMPT or IMRT with or without chemotherapy.

MAIN OUTCOMES AND MEASURES

The main outcomes were the incidence of acute and chronic (present after ≥6 months) treatment-related adverse events (AEs) and oncologic outcomes, including locoregional recurrence (LRR), progression-free survival (PFS), and overall survival (OS). Fisher exact tests and χ2 tests were used to evaluate associations between toxic effects and treatment modality (IMPT vs IMRT), and the Kaplan-Meier method was used to compare LRR, PFS, and OS between the 2 groups.

RESULTS

The study included 292 patients with OPC (272 [93%] with human papillomavirus [HPV]-p16-positive tumors); 254 (87%) were men, 38 (13%) were women, and the median age was 64 years (IQR, 58-71 years). Fifty-eight patients (20%) were treated with IMPT, and 234 (80%) were treated with IMRT. Median follow-up was 26 months (IQR, 17-36 months). Most patients (283 [97%]) received a dose to the primary tumor of 70 Gy. Fifty-seven of the patients treated with IMPT (98%) and 215 of those treated with IMRT (92%) had HPV-p16-positive disease. There were no significant differences in 3-year OS (97% IMPT vs 91% IMRT; P = .18), PFS (82% IMPT vs 85% IMRT; P = .62), or LRR (5% IMPT vs 4% IMRT; P = .59). The incidence of acute toxic effects was significantly higher for IMRT compared with IMPT for oral pain of grade 2 or greater (42 [72%] IMPT vs 217 [93%] IMRT; P < .001), xerostomia of grade 2 or greater (12 [21%] IMPT vs 68 [29%] IMRT; P < .001), dysgeusia of grade 2 or greater (16 [28%] IMPT vs 134 [57%] IMRT; P < .001), grade 3 dysphagia (4 [7%] IMPT vs 29 [12%] IMRT; P < .001), mucositis of grade 3 or greater (10 [53%] IMPT vs 13 [70%] IMRT; P = .003), nausea of grade 2 or greater (0 [0%] IMPT vs 18 [8%] IMRT; P = .04), and weight loss of grade 2 or greater (22 [37%] IMPT vs 138 [59%] IMRT; P < .001). There were no significant differences in chronic toxic effects of grade 3 or greater, although there was a significant difference for chronic xerostomia of grade 2 or greater (6 IMPT [11%] vs 22 IMRT [10%]; P < .001). Four patients receiving IMRT (2%) vs 0 receiving IMPT had a percutaneous endoscopic gastrostomy tube for longer than 6 months.

CONCLUSIONS AND RELEVANCE

In this study, curative-intent radiotherapy with IMPT for nonmetastatic OPC was associated with a significantly reduced acute toxicity burden compared with IMRT, with few chronic toxic effects and favorable oncologic outcomes, including locoregional recurrence of only 5% at 2 years. Prospective randomized clinical trials comparing these 2 technologies and of patient-reported outcomes are warranted.

Human Papillomavirus-Related Non-Metastatic Oropharyngeal Carcinoma: Current Local Treatment Options and Future Perspectives

Over the last two decades, human papillomavirus (HPV) has caused a new pandemic of cancer in many urban areas across the world. The new entity, HPV-associated oropharyngeal squamous cell carcinoma (OPSCC), has been at the center of scientific attention ever since, not only due to its distinct biological behavior, but also because of its significantly better prognosis than observed in its HPV-negative counterpart. The very good treatment outcomes of the disease after primary therapy (minimally-invasive surgery, radiation therapy with or without chemotherapy) resulted in the creation of a separate staging system, reflecting this excellent prognosis. A substantial proportion of newly diagnosed HPV-driven OPSCC is diagnosed in stage I or II, where long-term survival is observed worldwide. Deintensification of the primary therapeutic methods, aiming at a reduction of long-term toxicity in survivors, has emerged, and the quality of life of the patient after treatment has become a key-point in many clinical trials. Current treatment recommendations for the treatment of HPV-driven OPSCC do not differ significantly from HPV-negative OPSCC; however, the results of randomized trials are eagerly awaited and deemed necessary, in order to include deintensification into standard clinical practice.

Improving workflow for adaptive proton therapy with predictive anatomical modelling: A proof of concept

PURPOSE

To demonstrate predictive anatomical modelling for improving the clinical workflow of adaptive intensity-modulated proton therapy (IMPT) for head and neck cancer.

METHODS

10 radiotherapy patients with nasopharyngeal cancer were included in this retrospective study. Each patient had a planning CT, weekly verification CTs during radiotherapy and predicted weekly CTs from our anatomical model. Predicted CTs were used to create predicted adaptive plans in advance with the aim of maintaining clinically acceptable dosimetry. Adaption was triggered when the increase in mean dose (Dmean) to the parotid glands exceeded 3 Gy(RBE). We compared the accumulated dose of two adaptive IMPT strategies: 1) Predicted plan adaption: One adaptive plan per patient was optimised on a predicted CT triggered by replan criteria. 2) Standard replan: One adaptive plan was created reactively in response to the triggering weekly CT.

RESULTS

Statistical analysis demonstrates that the accumulated dose differences between two adaptive strategies are not significant (p > 0.05) for CTVs and OARs. We observed no meaningful differences in D95 between the accumulated dose and the planned dose for the CTVs, with mean differences to the high-risk CTV of -1.20 %, -1.23 % and -1.25 % for no adaption, standard and predicted plan adaption, respectively. The accumulated parotid Dmean using predicted plan adaption is within 3 Gy(RBE) of the planned dose and 0.31 Gy(RBE) lower than the standard replan approach on average.

CONCLUSION

Prediction-based replanning could potentially enable adaptive therapy to be delivered without treatment gaps or sub-optimal fractions, as can occur during a standard replanning strategy, though the benefit of using predicted plan adaption over the standard replan was not shown to be statistically significant with respect to accumulated dose in this study. Nonetheless, a predictive replan approach can offer advantages in improving clinical workflow efficiency.

Acute toxicity in patients treated with concurrent chemoradiotherapy with proton versus intensity-modulated radiation therapy for nonmetastatic head and neck cancers

BACKGROUND

We evaluated if proton therapy is associated with decreased acute toxicities compared to intensity-modulated radiation therapy (IMRT) in patients receiving concurrent chemoradiotherapy for head and neck cancers.

METHODS

We analyzed 580 patients with nonmetastatic head and neck cancers. Primary endpoint was any 90-day grade ≥3 toxicity, prospectively collected and graded per CTCAEv4. Modified Poisson regression models were used.

RESULTS

Ninety-five patients received proton and 485 IMRT. The proton group had more HPV-positive tumors (65.6 vs. 58.0%, p = 0.049), postoperative treatment (76.8 vs. 62.1%, p = 0.008), unilateral neck treatment (18.9 vs. 6.6%, p < 0.001) and significantly lower doses to organs-at-risk compared to IMRT group. Adjusted for patient and treatment characteristics, the proton group had decreased grade 2 dysgeusia (RR0.67, 95%CI 0.53-0.84, p = 0.004) and a trend toward lower grade ≥3 toxicities (RR0.60, 95%CI 0.41-0.88, p = 0.06).

CONCLUSIONS

Proton therapy was associated with significantly reduced grade 2 dysgeusia and nonstatistically significant decrease in acute grade ≥3 toxicities compared to IMRT.

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.

Estimating the percentage of patients who might benefit from proton beam therapy instead of X-ray radiotherapy

OBJECTIVES

High-energy Proton Beam Therapy (PBT) commenced in England in 2018 and NHS England commissions PBT for 1.5% of patients receiving radical radiotherapy. We sought expert opinion on the level of provision.

METHODS

Invitations were sent to 41 colleagues working in PBT, most at one UK centre, to contribute by completing a spreadsheet. 39 responded: 23 (59%) completed the spreadsheet; 16 (41%) declined, arguing that clinical outcome data are lacking, but joined six additional site-specialist oncologists for two consensus meetings. The spreadsheet was pre-populated with incidence data from Cancer Research UK and radiotherapy use data from the National Cancer Registration and Analysis Service. 'Mechanisms of Benefit' of reduced growth impairment, reduced toxicity, dose escalation and reduced second cancer risk were examined.

RESULTS

The most reliable figure for percentage of radical radiotherapy patients likely to benefit from PBT was that agreed by 95% of the 23 respondents at 4.3%, slightly larger than current provision. The median was 15% (range 4-92%) and consensus median 13%. The biggest estimated potential benefit was from reducing toxicity, median benefit to 15% (range 4-92%), followed by dose escalation median 3% (range 0 to 47%); consensus values were 12 and 3%. Reduced growth impairment and reduced second cancer risk were calculated to benefit 0.5% and 0.1%.

CONCLUSIONS

The most secure estimate of percentage benefit was 4.3% but insufficient clinical outcome data exist for confident estimates. The study supports the NHS approach of using the evidence base and developing it through randomised trials, non-randomised studies and outcomes tracking.

ADVANCES IN KNOWLEDGE

Less is known about the percentage of patients who may benefit from PBT than is generally acknowledged. Expert opinion varies widely. Insufficient clinical outcome data exist to provide robust estimates. Considerable further work is needed to address this, including international collaboration; much is already underway but will take time to provide mature data.

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 Novel Model and Infrastructure for Clinical Outcomes Data Collection and Their Systematic Evaluation for UK Patients Receiving Proton Beam Therapy

AIMS

To establish an infrastructure for sustainable, comprehensive data collection and systematic outcomes evaluation for UK patients receiving proton beam therapy (PBT).

MATERIALS AND METHODS

A Proton Outcomes Working Group was formed in 2014 to develop a national minimum dataset for PBT patients and to define a clinically integrated informatics solution for data collection. The Christie Proton Beam Therapy Centre formed its Proton Clinical Outcomes Unit in 2018 to collect, curate and analyse outcomes data prospectively for UK-treated patients and retrospectively for UK patients referred abroad for PBT since 2008 via the Proton Overseas Programme (POP).

RESULTS

A single electronic form (eForm) was developed to capture the agreed data, using a data tree approach including conditional logic: data items are requested once, further questions depend on previous answers and are sensitive to tumour site and patient pathway time point. Relevant data automatically populate other forms, saving time, prompting completeness of clinical assessments and ensuring data consistency. Completed eForm data populate the electronic patient record and generate individualised outputs, including consultation letters, treatment summary and surveillance plans, based on organs at risk irradiated, age and sex. All data regarding POP-treated patients are verified and migrated into the system, ensuring that patient data, whether overseas or UK treated, are consistently recorded. The eForm utilises a 'user friendly' web portal interface, the Clinical Web Portal, including clickable tables and infographics. Data items are coded to a universally recognised standard comparable with other data systems. Patient-reported outcomes are also integrated, highlighting significant toxicities and prompting a response. Outcomes data can be correlated with dosimetric DICOM data to support radiation dose modelling.

CONCLUSION

Outcomes data from both POP-treated and The Christie-treated patients support long-term care, allow evaluation of PBT efficacy and safety, assist future selection of PBT patients and support hypothesis generation for future clinical trials.

Repurposing Proton Beam Therapy through Novel Insights into Tumour Radioresistance

Despite improvements in radiotherapy, radioresistance remains an important clinical challenge. Radioresistance can be mediated through enhanced DNA damage response mechanisms within the tumour or through selective pressures exerted by the tumour microenvironment (TME). The effects of the TME have in recent times gained increased attention, in part due to the success of immune modulating strategies, but also through improved understanding of the downstream effects of hypoxia and dysregulated wound healing processes on mediating radioresistance. Although we have a better appreciation of these molecular mechanisms, efforts to address them through novel combination approaches have been scarce, owing to limitations of photon therapy and concerns over toxicity. At the same time, proton beam therapy (PBT) represents an advancement in radiotherapy technologies. However, early clinical results have been mixed and the clinical strategies around optimal use and patient selection for PBT remain unclear. Here we highlight the role that PBT can play in addressing radioresistance, through better patient selection, and by providing an improved toxicity profile for integration with novel agents. We will also describe the developments around FLASH PBT. Through close examination of its normal tissue-sparing effects, we will highlight how FLASH PBT can facilitate combination strategies to tackle radioresistance by further improving toxicity profiles and by directly mediating the mechanisms of radioresistance.

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.

Deintensification Strategies Using Proton Beam Therapy for HPV-Related Oropharyngeal Cancer

Oropharyngeal cancers related to the human papillomavirus are a growing segment of head and neck cancers throughout the world. These cancers are biologically and demographically unique with patients presenting at younger ages and with more curable disease. This combination of factors heightens the importance of normal tissue sparing because patients will live a long time with treatment sequelae. Proton therapy has demonstrated benefits in reducing normal tissue exposure, which may lead to less toxicity, a higher quality of life, less immunologic suppression, and lower cost. Research investigating deintensified radiation volumes and doses are also underway. These deintensification studies synergize well with the beam characteristics of proton beam therapy and can decrease that already reduced normal tissue exposure enabled by proton therapy. Future studies should refine patient selection to best allow for volume and dose reduction paired with proton therapy.

Proton Therapy for HPV-Associated Oropharyngeal Cancers of the Head and Neck: a De-Intensification Strategy

The rise in the incidence of human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPC), the relatively young age at which it is diagnosed, and its favorable prognosis necessitate the use of treatment techniques that reduce the likelihood of side effects during and after curative treatment. Intensity-modulated proton therapy (IMPT) is a form of radiotherapy that de-intensifies treatment through dose de-escalation to normal tissues without compromising dose to the primary tumor and involved, regional lymph nodes. Preclinical studies have demonstrated that HPV-positive squamous cell carcinoma is more sensitive to proton radiation than is HPV-negative squamous cell carcinoma. Retrospective studies comparing intensity-modulated photon (X-ray) radiotherapy to IMPT for OPC suggest comparable rates of disease control and lower rates of pain, xerostomia, dysphagia, dysgeusia, gastrostomy tube dependence, and osteoradionecrosis with IMPT—all of which meaningfully affect the quality of life of patients treated for HPV-associated OPC. Two phase III trials currently underway—the “Randomized Trial of IMPT versus IMRT for the Treatment of Oropharyngeal Cancer of the Head and Neck” and the “TOxicity Reduction using Proton bEam therapy for Oropharyngeal cancer (TORPEdO)” trial—are expected to provide prospective, level I evidence regarding the effectiveness of IMPT for such patients.

The Promise of Proton Beam Therapy for Oesophageal Cancer: A Systematic Review of Dosimetric and Clinical Outcomes

AIMS

Due to its physical advantages over photon radiotherapy, proton beam therapy (PBT) has the potential to improve outcomes from oesophageal cancer. However, for many tumour sites, high-quality evidence supporting PBT use is limited. We carried out a systematic review of published literature of PBT in oesophageal cancer to ascertain potential benefits of this technology and to gauge the current state-of-the-art. We considered if further evaluation of this technology in oesophageal cancer is desirable.

MATERIALS AND METHODS

A systematic literature search of Medline, Embase, Cochrane Library and Web of Science using structured search terms was carried out. Inclusion criteria included non-metastatic cancer, full articles and English language studies only. Articles deliberating technical aspects of PBT planning or delivery were excluded to maintain a clinical focus. Studies were divided into two sections: dosimetric and clinical studies; qualitatively synthesised.

RESULTS

In total, 467 records were screened, with 32 included for final qualitative synthesis. This included two prospective studies with the rest based on retrospective data. There was heterogeneity in treatment protocols, including treatment intent (neoadjuvant or definitive), dose, fractionation and chemotherapy used. Compared with photon radiotherapy, PBT seemed to reduce dose to organs at risk, especially lung and heart, although not for all reported parameters. Toxicity outcomes, including postoperative complications, were reduced compared with photon radiotherapy. Survival outcomes were reported to be at least comparable with photon radiotherapy.

CONCLUSION

There is a paucity of high-quality evidence supporting PBT use in oesophageal cancer. Wide variation in intent and treatment protocols means that the role and 'gold-standard' treatment protocol are yet to be defined. Current literature suggests significant benefit in terms of toxicity reduction, especially in the postoperative period, with comparable survival outcomes. PBT in oesophageal cancer holds significant promise for improving patient outcomes but requires robust systematic evaluation in prospective studies.

Patient and Public Involvement Refines the Design of ProtOeus: A Proposed Phase II Trial of Proton Beam Therapy in Oesophageal Cancer

BACKGROUND

Neoadjuvant chemoradiotherapy for oesophageal cancer significantly improves overall survival but is associated with severe post-operative complications. Proton beam therapy may reduce these toxicities by sparing normal tissues compared with standard radiotherapy. ProtOeus is a proposed randomised phase II study of neoadjuvant chemoradiotherapy in oesophageal cancer that compares proton beam therapy to standard radiotherapy techniques. As proton beam therapy services are often centralised in academic centres in major cities, proton beam therapy trials raise distinct challenges including patient acceptance of travelling for proton beam therapy, coordination of treatments with local centres and ensuring equity of access for patients.

METHODS

Focus groups were held early in the trial development process to establish patients' views on the trial proposal. Topics discussed include perception of proton beam therapy, patient acceptability of the trial pathway and design, patient-facing materials, and common clinical scenarios. Focus groups were led by the investigators and facilitated by patient involvement teams from the institutions who are involved in this research. Responses for each topic were analysed, and fed back to the trial's development group.

RESULTS

Three focus groups were held in separate locations in the UK (Manchester, Cardiff, Wigan). Proton beam therapy was perceived as superior to standard radiotherapy making the trial attractive. Patients felt strongly that travel costs should be reimbursed to ensure equity of access to proton beam therapy. They were very supportive of a shorter treatment schedule and felt that toxicity reduction was the most important endpoint.

DISCUSSION AND CONCLUSIONS

Incorporating patient views early in the trial development process resulted in significant trial design refinements including travel/accommodation provisions, choice of primary endpoint, randomisation ratio and fractionation schedule. Focus groups are a reproducible and efficient method of incorporating the patient and public voice into research.

Heavy charged particle beam therapy and related new radiotherapy technologies: The clinical potential, physics and technical developments required to deliver benefit for patients with cancer

In the UK, one in two people will develop cancer during their lifetimes and radiotherapy (RT) plays a key role in effective treatment. High energy proton beam therapy commenced in the UK National Health Service in 2018. Heavier charged particles have potential advantages over protons by delivering more dose in the Bragg peak, with a sharper penumbra, lower oxygen dependence and increased biological effectiveness. However, they also require more costly equipment including larger gantries to deliver the treatment. There are significant uncertainties in the modelling of relative biological effectiveness and the effects of the fragmentation tail which can deliver dose beyond the Bragg peak. These effects need to be carefully considered especially in relation to long-term outcomes.In 2019, a group of clinicians, clinical scientists, engineers, physical and life scientists from academia and industry, together with funding agency stakeholders, met to consider how the UK should address new technologies for RT, especially the use of heavier charged particles such as helium and carbon and new modes of delivery such as FLASH and spatially fractionated radiotherapy (SFRT).There was unanimous agreement that the UK should develop a facility for heavier charged particle therapy, perhaps constituting a new National Ion Research Centre to enable research using protons and heavier charged particles. Discussion followed on the scale and features, including which ions should be included, from protons through helium, boron, and lithium to carbon, and even oxygen. The consensus view was that any facility intended to treat patients must be located in a hospital setting while providing dedicated research space for physics, preclinical biology and clinical research with beam lines designed for both in vitro and in vivo research. The facility should to be able to investigate and deliver both ultra-high dose rate FLASH RT and SFRT (GRID, minibeams etc.). Discussion included a number of accelerator design options and whether gantries were required. Other potential collaborations might be exploited, including with space agencies, electronics and global communications industries and the nuclear industry.In preparation for clinical delivery, there may be opportunities to send patients overseas (for 12C or 4He ion therapy) using the model of the National Health Service (NHS) Proton Overseas Programme and to look at potential national clinical trials which include heavier ions, FLASH or SFRT. This could be accomplished under the auspices of NCRI CTRad (National Cancer Research Institute, Clinical and Translational Radiotherapy Research Working Group).The initiative should be a community approach, involving all interested parties with a vision that combines discovery science, a translational research capability and a clinical treatment facility. Barriers to the project and ways to overcome them were discussed. Finally, a set of different scenarios of features with different costs and timelines was constructed, with consideration given to the funding environment (prer-Covid-19) and need for cross-funder collaboration.

Proton therapy and the European Particle Therapy Network: The past, present and future

Proton therapy is delivered to selected cancer patients presenting with rare tumours, for which a dose escalation paradigm and/or a reduced dose-bath to the organs at risk is pursued. It is a costly treatment with an additional cost factor of 2–3 when compared to photon radiotherapy. Notwithstanding the 180′000 patients treated with protons, scars robust clinical evidence is available to justify the administration of this treatment modality. The European Particle Therapy Network (EPTN) was created in 2015 to answer the critical European needs for cooperation among protons and carbon ions centres in the framework of clinical research networks. EPTN with other European groups will launch a number of prospective clinical trials that could be practice changing if positive. Alternative way to generate clinical data could be provided by alternative methodologies, such as the Dutch model-based approach, or could be provided by European infrastructure projects.

Comparing Proton to Photon Radiotherapy Plans: UK Consensus Guidance for Reporting Under Uncertainty for Clinical Trials

In the UK, the recent introduction of high-energy proton beam therapy into national clinical practice provides an opportunity for new clinical trials, particularly those comparing proton and photon treatments. However, comparing these different modalities can present many challenges. Although protons may confer an advantage in terms of reduced normal tissue dose, they can also be more sensitive to uncertainty. Uncertainty analysis is fundamental in ensuring that proton plans are both safe and effective in the event of unavoidable discrepancies, such as variations in patient setup and proton beam range. Methods of evaluating and mitigating the effect of these uncertainties can differ from those approaches established for photon therapy treatments, such as the use of expansion margins to assure safety. These differences should be considered when comparing protons and photons. An overview of the effect of uncertainties on proton plans is presented together with an introduction to some of the concepts and terms that should become familiar to those involved in proton therapy trials. This report aims to provide guidance for those engaged in UK clinical trials comparing protons and photons. This guidance is intended to take a pragmatic approach considering the tools that are available to practising centres and represents a consensus across multidisciplinary groups involved in proton therapy in the UK.

Particle therapy in Europe

Particle therapy using protons or heavier ions is currently the most advanced form of radiotherapy and offers new opportunities for improving cancer care and research. Ions deposit the dose with a sharp maximum – the Bragg peak – and normal tissue receives a much lower dose than what is delivered by X‐ray therapy. Particle therapy has also biological advantages due to the high linear energy transfer of the charged particles around the Bragg peak. The introduction of particle therapy has been slow in Europe, but within the last decade, more than 20 clinical facilities have opened and facilitated access to this frontline therapy. In this review article, the basic concepts of particle therapy are reviewed along with a presentation of the current clinical indications, the European clinical research, and the established networks.

Proton beam therapy: perspectives on the National Health Service England clinical service and research programme

The UK has an important role in the evaluation of proton beam therapy (PBT) and takes its place on the world stage with the opening of the first National Health Service (NHS) PBT centre in Manchester in 2018, and the second in London coming in 2020. Systematic evaluation of the role of PBT is a key objective. By September 2019, 108 patients had started treatment, 60 paediatric, 19 teenagers and young adults and 29 adults. Obtaining robust outcome data is vital, if we are to understand the strengths and weaknesses of current treatment approaches. This is important in demonstrating when PBT will provide an advantage and when it will not, and in quantifying the magnitude of benefit.The UK also has an important part to play in translational PBT research, and building a research capability has always been the vision. We are perfectly placed to perform translational pre-clinical biological and physical experiments in the dedicated research room in Manchester. The nature of DNA damage from proton irradiation is considerably different from X-rays and this needs to be more fully explored. A better understanding is needed of the relative biological effectiveness (RBE) of protons, especially at the end of the Bragg peak, and of the effects on tumour and normal tissue of PBT combined with conventional chemotherapy, targeted drugs and immunomodulatory agents. These experiments can be enhanced by deterministic mathematical models of the molecular and cellular processes of DNA damage response. The fashion of ultra-high dose rate FLASH irradiation also needs to be explored.

Reduced radiation-induced toxicity by using proton therapy for the treatment of oropharyngeal cancer

Patients with squamous cell carcinoma of the oropharynx are generally treated with (chemo) radiation. Patients with oropharyngeal cancer have better survival than patients with squamous cell carcinoma of other head and neck subsites, especially when related to human papillomavirus. However, radiotherapy results in a substantial percentage of survivors suffering from significant treatment-related side-effects. Late radiation-induced side-effects are mostly irreversible and may even be progressive, and particularly xerostomia and dysphagia affect health-related quality of life. As the risk of radiation-induced side-effects highly depends on dose to healthy normal tissues, prevention of radiation-induced xerostomia and dysphagia and subsequent improvement of health-relatedquality of life can be obtained by applying proton therapy, which offers the opportunity to reduce the dose to both the salivary glands and anatomic structures involved in swallowing.This review describes the results of the first cohort studies demonstrating that proton therapy results in lower dose levels in multiple organs at risk, which translates into reduced acute toxicity (i.e. up to 3 months after radiotherapy), while preserving tumour control. Next to reducing mucositis, tube feeding, xerostomia and distortion of the sense of taste, protons can improve general well-being by decreasing fatigue and nausea. Proton therapy results in decreased rates of tube feeding dependency and severe weight loss up to 1 year after radiotherapy, and may decrease the risk of radionecrosis of the mandible. Also, the model-based approach for selecting patients for proton therapy in the Netherlands is described in this review and future perspectives are discussed.