C. elegans: A potent model for high-throughput screening experiments investigating the FLASH effect

This study explores the effects of UHDR irradiation on Caenorhabditis elegans embryos. UHDR proton and electron beams demonstrate a sparing effect, aligning with literature findings. This highlights C. elegans suitability as a screening model for studying the LET impact on the FLASH effect, reinforcing its potential in radiation research.

Correction: Krayem et al. The Benefit of Reactivating p53 under MAPK Inhibition on the Efficacy of Radiotherapy in Melanoma. Cancers 2019, 11, 1093

In the original article [...].

First-in-human study of SBRT and adenosine pathway blockade to potentiate the benefit of immunochemotherapy in early-stage luminal B breast cancer: results of the safety run-in phase of the Neo-CheckRay trial

BACKGROUND

Luminal B breast cancer (BC) presents a worse prognosis when compared with luminal A BC and exhibits a lower sensitivity to chemotherapy and a lower immunogenicity in contrast to non-luminal BC subtypes. The Neo-CheckRay clinical trial investigates the use of stereotactic body radiation therapy (SBRT) directed to the primary tumor in combination with the adenosine pathway inhibitor oleclumab to improve the response to neo-adjuvant immuno-chemotherapy in luminal B BC. The trial consists of a safety run-in followed by a randomized phase II trial. Here, we present the results of the first-in-human safety run-in.

METHODS

The safety run-in was an open-label, single-arm trial in which six patients with early-stage luminal B BC received the following neo-adjuvant regimen: paclitaxel q1w×12 → doxorubicin/cyclophosphamide q2w×4; durvalumab (anti-programmed cell death receptor ligand 1 (PD-L1)) q4w×5; oleclumab (anti-CD73) q2w×4 → q4w×3 and 3×8 Gy SBRT to the primary tumor at week 5. Surgery must be performed 2-6 weeks after primary systemic treatment and adjuvant therapy was given per local guidelines, RT boost to the tumor bed was not allowed. Key inclusion criteria were: luminal BC, Ki67≥15% or histological grade 3, MammaPrint high risk, tumor size≥1.5 cm. Primary tumor tissue samples were collected at three timepoints: baseline, 1 week after SBRT and at surgery. Tumor-infiltrating lymphocytes, PD-L1 and CD73 were evaluated at each timepoint, and residual cancer burden (RCB) was calculated at surgery.

RESULTS

Six patients were included between November 2019 and March 2020. Median age was 53 years, range 37-69. All patients received SBRT and underwent surgery 2-4 weeks after the last treatment. After a median follow-up time of 2 years after surgery, one grade 3 adverse event (AE) was reported: pericarditis with rapid resolution under corticosteroids. No grade 4-5 AE were documented. Overall cosmetical breast evaluation after surgery was 'excellent' in four patients and 'good' in two patients. RCB results were 2/6 RCB 0; 2/6 RCB 1; 1/6 RCB 2 and 1/6 RCB 3.

CONCLUSIONS

This novel treatment combination was considered safe and is worth further investigation in a randomized phase II trial.

TRIAL REGISTRATION NUMBER

NCT03875573.

Acoustic Analysis of Voluntary Coughs, Throat Clearings, and Induced Reflexive Coughs in a Healthy Population

Cough efficacy is considered a reliable predictor of the aspiration risk in head and neck cancer patients with radiation-associated dysphagia. Currently, coughing is assessed perceptually or aerodynamically. The goal of our research is to develop methods of acoustic cough analysis. In this study, we examined in a healthy population the acoustical differences between three protective maneuvers: voluntary cough, voluntary throat clearing, and induced reflexive cough. Forty healthy participants were included in this study. Voluntary cough, voluntary throat clearing, and reflexive cough samples were recorded and analyzed acoustically. Temporal acoustic features were the following: the slope and curvature of the amplitude contour, as well as the average, slope, and curvature of the sample entropy and kurtosis contours of the recorded signal. Spectral features were the relative energy in the frequency bands (0-400 Hz, 400-800 Hz, 800-1600 Hz, 1600 Hz-3200 Hz, > 3200 Hz) as well as the weighted spectral energy. Results showed that, compared to a voluntary cough, a throat clearing starts with a weaker onset pulse and involves oscillations from the onset to the offset (concave curvature of the amplitude contour, p < 0.05), lower average (p < 0.05), and slope (p < 0.05) as well as lower convex curvature (p < 0.05) of the kurtosis contour. An induced reflexive cough starts with a higher and briefer onset burst and includes higher frication noise (larger convexity of the curvature of the amplitude and kurtosis contours (p < 0.05)) compared to a voluntary cough. The conclusion is that voluntary coughs are acoustically significantly different from voluntary throat clearings and induced reflexive coughs.

A CT-based radiomics classification model for the prediction of histological type and tumour grade in retroperitoneal sarcoma (RADSARC-R): a retrospective multicohort analysis

BACKGROUND

Retroperitoneal sarcomas are tumours with a poor prognosis. Upfront characterisation of the tumour is difficult, and under-grading is common. Radiomics has the potential to non-invasively characterise the so-called radiological phenotype of tumours. We aimed to develop and independently validate a CT-based radiomics classification model for the prediction of histological type and grade in retroperitoneal leiomyosarcoma and liposarcoma.

METHODS

A retrospective discovery cohort was collated at our centre (Royal Marsden Hospital, London, UK) and an independent validation cohort comprising patients recruited in the phase 3 STRASS study of neoadjuvant radiotherapy in retroperitoneal sarcoma. Patients aged older than 18 years with confirmed primary leiomyosarcoma or liposarcoma proceeding to surgical resection with available contrast-enhanced CT scans were included. Using the discovery dataset, a CT-based radiomics workflow was developed, including manual delineation, sub-segmentation, feature extraction, and predictive model building. Separate probabilistic classifiers for the prediction of histological type and low versus intermediate or high grade tumour types were built and tested. Independent validation was then performed. The primary objective of the study was to develop radiomic classification models for the prediction of retroperitoneal leiomyosarcoma and liposarcoma type and histological grade.

FINDINGS

170 patients recruited between Oct 30, 2016, and Dec 23, 2020, were eligible in the discovery cohort and 89 patients recruited between Jan 18, 2012, and April 10, 2017, were eligible in the validation cohort. In the discovery cohort, the median age was 63 years (range 27-89), with 83 (49%) female and 87 (51%) male patients. In the validation cohort, median age was 59 years (range 33-77), with 46 (52%) female and 43 (48%) male patients. The highest performing model for the prediction of histological type had an area under the receiver operator curve (AUROC) of 0·928 on validation, based on a feature set of radiomics and approximate radiomic volume fraction. The highest performing model for the prediction of histological grade had an AUROC of 0·882 on validation, based on a radiomics feature set.

INTERPRETATION

Our validated radiomics model can predict the histological type and grade of retroperitoneal sarcomas with excellent performance. This could have important implications for improving diagnosis and risk stratification in retroperitoneal sarcomas.

FUNDING

Wellcome Trust, European Organisation for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group, the National Institutes for Health, and the National Institute for Health and Care Research Biomedical Research Centre at The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research.

Assessment of radio(chemo)therapy-related dysphagia in head and neck cancer patients based on cough-related acoustic features: a prospective phase II national clinical trial (ACCOUGH-P/A trial)

BACKGROUND

Radiation-associated dysphagia is defined as impaired swallowing efficiency/safety following (chemo)radiotherapy in head and neck cancer patients. In a dysphagia framework, impaired coughing may lead to lung aspiration and fatal lung infection. Although cough efficacy is a predictor of the risk of aspiration, cough investigation is minimal in patients with radiation-associated dysphagia. Because cough is a transient signal, existing software for speech analysis are not appropriate. The goal of our project is to develop an assessment method using acoustic features related to voluntary and reflexive coughs as biomarkers of the risk of penetration/aspiration in patients with radiation-associated dysphagia.

METHODS

Healthy subjects and head and neck cancer patients with and without dysphagia will produce voluntary coughs, throat clearings and reflexive coughs. Recordings will be made using an acoustic microphone and a throat microphone. The recorded signals will be manually segmented and subsequently analysed with a software under development. Automatic final segmentation enables to measure cough duration. The first method of analysis includes temporal features: the amplitude contour, the sample entropy and the kurtosis. These features report respectively the strength, the unpredictability (turbulence noise due to the air jet) and the impulsive quality (burst) of the signal. The second method of analysis consists of a spectral decomposition of the relative cough signal energy into several frequency bands (0-400 Hz, 400-800 Hz, 800-1600 Hz, 1600-3200 Hz, > 3200 Hz). The primary outcome of this exploratory research project is the identification of a set of descriptive acoustic cough features in healthy subjects as reference data (ACCOUGH). The secondary outcome of this research in head and neck cancer patients with radiation-associated dysphagia includes the identification of (1) a set of descriptive acoustic cough features as biomarkers of penetration-aspiration (ACCOUGH-P/A), (2) swallowing scores, (3) voice features and (4) aerodynamic cough features.

DISCUSSION

This study is expected to develop methods of acoustic cough analysis to enhance the assessment of radiation-associated dysphagia in head and neck cancer patients following (chemo)radiation.

TRIAL REGISTRATION

International Standard Randomized Controlled Trials Number (ISRCTN) registry ISRCTN16540497. Accepted on 23 June 2023.

Checkpoint Inhibitors in Combination With Stereotactic Body Radiotherapy in Patients With Advanced Solid Tumors: The CHEERS Phase 2 Randomized Clinical Trial

Importance

Although immune checkpoint inhibitors (ICIs) targeting programmed cell death 1 (PD-1) and PD-1 ligand 1 have improved the outcome for many cancer types, the majority of patients fails to respond to ICI monotherapy. Hypofractionated radiotherapy has the potential to improve the therapeutic ratio of ICIs.

Objective

To assess the addition of radiotherapy to ICIs compared with ICI monotherapy in patients with advanced solid tumors.

Design, Setting, and Participants

This open-label, multicenter, randomized phase 2 trial was conducted in 5 Belgian hospitals and enrolled participants between March 2018 and October 2020. Patients 18 years or older with locally advanced or metastatic melanoma, renal cell carcinoma, urothelial carcinoma, head and neck squamous cell carcinoma, or non-small cell lung carcinoma were eligible. A total of 99 patients were randomly assigned to either the control arm (n = 52) or the experimental arm (n = 47). Of those, 3 patients (1 in the control arm vs 2 in the experimental arm) withdrew consent and thus were not included in the analysis. Data analyses were performed between April 2022 and March 2023.

Interventions

Patients were randomized (1:1) to receive anti-PD-1/PD-1 ligand 1 ICIs alone as per standard of care (control arm) or combined with stereotactic body radiotherapy 3 × 8 gray to a maximum of 3 lesions prior to the second or third ICI cycle, depending on the frequency of administration (experimental arm). Randomization was stratified according to tumor histologic findings and disease burden (3 and fewer or more than 3 cancer lesions).

Main Outcomes and Measures

The primary end point was progression-free survival (PFS) as per immune Response Evaluation Criteria in Solid Tumors. Key secondary end points included overall survival (OS), objective response rate, local control rate, and toxic effects. Efficacy was assessed in the intention-to-treat population, while safety was evaluated in the as-treated population.

Results

Among 96 patients included in the analysis (mean age, 66 years; 76 [79%] female), 72 (75%) had more than 3 tumor lesions and 65 (68%) had received at least 1 previous line of systemic treatment at time of inclusion. Seven patients allocated to the experimental arm did not complete the study-prescribed radiotherapy course due to early disease progression (n = 5) or intercurrent illness (n = 2). With a median (range) follow-up of 12.5 (0.7-46.2) months, median PFS was 2.8 months in the control arm compared with 4.4 months in the experimental arm (hazard ratio, 0.95; 95% CI, 0.58-1.53; P = .82). Between the control and experimental arms, no improvement in median OS was observed (11.0 vs 14.3 months; hazard ratio, 0.82; 95% CI, 0.48-1.41; P = .47), and objective response rate was not statistically significantly different (22% vs 27%; P = .56), despite a local control rate of 75% in irradiated patients. Acute treatment-related toxic effects of any grade and grade 3 or higher occurred in 79% and 18% of patients in the control arm vs 78% and 18% in the experimental arm, respectively. No grade 5 adverse events occurred.

Conclusions and Relevance

This phase 2 randomized clinical trial demonstrated that while safe, adding subablative stereotactic radiotherapy of a limited number of metastatic lesions to ICI monotherapy failed to show improvement in PFS or OS.

Trial Registration

ClinicalTrials.gov Identifier: NCT03511391.

Boost modalities in cervical cancer: dosimetric comparison between intracavitary BT vs. intracavitary + interstitial BT vs. SBRT

PURPOSE / OBJECTIVE

This study compares the dosimetric plans of three distinct boost modalities in cervical cancer (CC): intracavitary (IC) with tandem/ovoids brachytherapy (BT), IC + interstitial (IS) BT, and Stereotactic-Body-Radiotherapy (SBRT). The aim is to determine the dosimetric impact in terms of target coverage and organ at risk (OAR) doses.

MATERIALS AND METHODS

24 consecutive IC + IS BT boost treatment plans were retrospectively identified. For each plan included, two additional plans were created: IC-BT and SBRT. Importantly, no planning target volume (PTV) or planning (organ at) risk volume (PRV) margins were generated, therefore all structures were identical for any boost modality. Two different normalizations were performed: (1) Normalization to the target: prescription of 7.1 Gy to the D90% (defined as the minimum dose covering 90%) of the high-risk clinical target volume (HR-CTV); (2) Normalization to the OARs. HR-CTV coverage and OARs sparing were compared. The equivalent doses in 2 Gy fractions (EQD2) of EBRT and BT for CTV-HR and OARs were calculated using the linear-quadratic model with α/β of 10 (EQD2₁₀) and 3 (EQD2₃), respectively RESULTS: A total of 72 plans were investigated. In the first normalization, the mean EQD2_3-D2cc (defined as the minimal dose of the 2 cc) of OAR was significantly higher in the IC-BT plans, and the bladder D2cc hard constraint could not be reached. IC + IS BT leads to a 1 Gy mean absolute decrease of bladder EQD2₃-D2cc (relative dose: -19%), allowing to reach the hard constraint. SBRT (without PTV) delivers the lowest EQD2₃-D2cc to the OAR. In the second normalization, IC-BT provides a significantly lower dose to the EQD2₁₀-D90% (6.62 Gy) and cannot achieve the coverage goal. SBRT (without PTV) yields the highest dose to the D90% of HR-CTV and a significantly lower EQD2₁₀-D50% and D30%.

CONCLUSION

The key dosimetric benefit of BT over SBRT without PTV is a significantly higher D50% and D30% in the HR-CTV, which increases the local and conformal dose to the target. IC + IS BT vs. IC-BT provides significantly better target coverage and a lower dose to the OARs, making it the preferred boost modality in CC.

The benefit of co-targeting PARP-1 and c-Met on the efficacy of radiotherapy in wild type BRAF melanoma

Melanoma is known to be a radioresistant cancer. Melanoma radioresistance can be due to several factors such as pigmentation, antioxidant defenses and high Deoxyribonucleic acid (DNA) repair efficacy. However, irradiation induces intracellular translocation of RTKs, including cMet, which regulates response to DNA damage activating proteins and promotes DNA repair. Accordingly, we hypothesized that co-targeting DNA repair (PARP-1) and relevant activated RTKs, c-Met in particular, may radiosensitize wild-type B-Raf Proto-Oncogene, Serine/Threonine Kinase (WTBRAF) melanomas where RTKs are often upregulated. Firstly, we found that PARP-1 is highly expressed in melanoma cell lines. PARP-1 inhibition by Olaparib or its KO mediates melanoma cell sensitivity to radiotherapy (RT). Similarly, specific inhibition of c-Met by Crizotinib or its KO radiosensitizes the melanoma cell lines. Mechanistically, we show that RT causes c-Met nuclear translocation to interact with PARP-1 promoting its activity. This can be reversed by c-Met inhibition. Accordingly, RT associated with the inhibition of both c-Met and PARP-1 resulted in a synergistic effect not only on tumor growth inhibition but also on tumor regrowth control in all animals following the stop of the treatment. We thus show that combining PARP and c-Met inhibition with RT appears a promising therapeutic approach in WTBRAF melanoma.

The current understanding of the immune landscape relative to radiotherapy across tumor types

Radiotherapy is part of the standard of care treatment for a great majority of cancer patients. As a result of radiation, both tumor cells and the environment around them are affected directly by radiation, which mainly primes but also might limit the immune response. Multiple immune factors play a role in cancer progression and response to radiotherapy, including the immune tumor microenvironment and systemic immunity referred to as the immune landscape. A heterogeneous tumor microenvironment and the varying patient characteristics complicate the dynamic relationship between radiotherapy and this immune landscape. In this review, we will present the current overview of the immunological landscape in relation to radiotherapy in order to provide insight and encourage research to further improve cancer treatment. An investigation into the impact of radiation therapy on the immune landscape showed in several cancers a common pattern of immunological responses after radiation. Radiation leads to an upsurge in infiltrating T lymphocytes and the expression of programmed death ligand 1 (PD-L1) which can hint at a benefit for the patient when combined with immunotherapy. In spite of this, lymphopenia in the tumor microenvironment of 'cold' tumors or caused by radiation is considered to be an important obstacle to the patient's survival. In several cancers, a rise in the immunosuppressive populations is seen after radiation, mainly pro-tumoral M2 macrophages and myeloid-derived suppressor cells (MDSCs). As a final point, we will highlight how the radiation parameters themselves can influence the immune system and, therefore, be exploited to the advantage of the patient.

Combination, Modulation and Interplay of Modern Radiotherapy with the Tumor Microenvironment and Targeted Therapies in Pancreatic Cancer: Which Candidates to Boost Radiotherapy?

Pancreatic ductal adenocarcinoma cancer (PDAC) is a highly diverse disease with low tumor immunogenicity. PDAC is also one of the deadliest solid tumor and will remain a common cause of cancer death in the future. Treatment options are limited, and tumors frequently develop resistance to current treatment modalities. Since PDAC patients do not respond well to immune checkpoint inhibitors (ICIs), novel methods for overcoming resistance are being explored. Compared to other solid tumors, the PDAC's tumor microenvironment (TME) is unique and complex and prevents systemic agents from effectively penetrating and killing tumor cells. Radiotherapy (RT) has the potential to modulate the TME (e.g., by exposing tumor-specific antigens, recruiting, and infiltrating immune cells) and, therefore, enhance the effectiveness of targeted systemic therapies. Interestingly, combining ICI with RT and/or chemotherapy has yielded promising preclinical results which were not successful when translated into clinical trials. In this context, current standards of care need to be challenged and transformed with modern treatment techniques and novel therapeutic combinations. One way to reconcile these findings is to abandon the concept that the TME is a well-compartmented population with spatial, temporal, physical, and chemical elements acting independently. This review will focus on the most interesting advancements of RT and describe the main components of the TME and their known modulation after RT in PDAC. Furthermore, we will provide a summary of current clinical data for combinations of RT/targeted therapy (tRT) and give an overview of the most promising future directions.

Patient-reported outcomes in terms of swallowing and quality of life after prophylactic versus reactive percutaneous endoscopic gastrostomy tube placement in advanced oropharyngeal cancer patients treated with definitive chemo-radiotherapy: Swall PEG study

BACKGROUND

Percutaneous endoscopic gastrostomy (PEG) is often used to provide nutritional support in locally advanced head and neck cancer patients undergoing multimodality treatment. However, there is little published data on the impact of prophylactic versus reactive PEG. PEG placement may affect swallowing-related physiology, function, and quality of life. The Swall PEG study is a randomized controlled phase III trial testing the impact of prophylactic versus reactive PEG on patient-reported outcomes in terms of swallowing and quality of life in oropharyngeal cancer patients.

METHODS

Patients with locally advanced oropharyngeal cancer receiving chemo-radiotherapy will be randomized to either the prophylactic or reactive PEG tube group. Randomization will be stratified by human papillomavirus (HPV) status and unilateral versus bilateral positive neck lymph nodes. The primary objective of the study is the patient's reported outcome in terms of swallowing (MD Anderson Dysphagia Inventory (MDADI)) at 6 months. Secondary objectives include health-related quality of life, dosimetric parameters associated with patient-reported outcomes, chemo-radiation toxicities, PEG tube placement complications, the impact of nutritional status on survival and toxicity outcomes, loco-regional control, overall survival, the impact of HPV and tobacco smoking on survival outcomes and toxicities, and the cost-effectiveness of each treatment strategy.

DISCUSSION

Findings from this study will enhance clinical evidence regarding nutritional management in oropharyngeal cancer patients treated by concurrent chemo-radiation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04019548, study protocol version 2.0_08/08/2019. Registered on 15 July 2019.

Intraoperative electron radiotherapy in early invasive ductal breast cancer: 6-year median follow-up results of a prospective monocentric registry

Background

Intraoperative electron radiotherapy (IOERT) can be used to treat early breast cancer during the conservative surgery thus enabling shorter overall treatment times and reduced irradiation of organs at risk. We report on our first 996 patients enrolled prospectively in a registry trial.

Methods

At Jules Bordet Institute, from February 2010 onwards, patients underwent partial IOERT of the breast. Women with unifocal invasive ductal carcinoma, aged 40 years or older, with a clinical tumour size ≤ 20 mm and tumour-free sentinel lymph node (on frozen section and immunohistochemical analysis). A 21 Gy dose was prescribed on the 90% isodose line in the tumour bed with the energy of 6 to 12 MeV (Mobetron®-IntraOp Medical).

Results

Thirty-seven ipsilateral tumour relapses occurred. Sixteen of those were in the same breast quadrant. Sixty patients died, and among those, 12 deaths were due to breast cancer. With 71.9 months of median follow-up, the 5-year Kaplan–Meier estimate of local recurrence was 2.7%.

Conclusions

The rate of breast cancer local recurrence after IOERT is low and comparable to published results for IORT and APBI. IOERT is highly operator-dependent, and appropriate applicator sizing according to tumour size is critical. When used in a selected patient population, IOERT achieves a good balance between tumour control and late radiotherapy-mediated toxicity morbidity and mortality thanks to insignificant irradiation of organs at risk.

Isotoxic High-Dose Stereotactic Body Radiotherapy (iHD-SBRT) Versus Conventional Chemoradiotherapy for Localized Pancreatic Cancer: A Single Cancer Center Evaluation

Given the lack of direct comparative evidence, we aimed to compare the oncological outcomes of localized pancreatic ductal adenocarcinoma (PDAC) treated in the same tertiary cancer center with isotoxic high-dose stereotactic body radiotherapy (iHD-SBRT) or conventional chemoradiotherapy (CRT). Biopsy-proven borderline/locally advanced patients treated with iHD-SBRT (35 Gy in 5 fractions with a simultaneous integrated boost up to 53 Gy) or CRT (45−60 Gy in 25−30 fractions) were retrospectively included from January 2006 to January 2021. The median overall survival (mOS) was evaluated trough uni- and multivariate analyses. The progression free survival (PFS) and the 1-year local control (1-yLC) were also reported. Eighty-two patients were included. The median follow-up was 19.7 months. The mOS was in favour of the iHD-SBRT group (22.5 vs. 15.9 months, p < 0.001), including after multivariate analysis (HR 0.39 [CI95% 0.18−0.83], p = 0.014). The median PFS and the 1-yLC were also significantly better for iHD-SBRT (median PFS: 16.7 vs. 11.5 months, p = 0.011; 1-yLC: 75.8 vs. 39.3%, p = 0.004). In conclusion, iHD-SBRT is a promising RT option and may offer an improvement in OS in comparison to CRT for localized PDAC. Further validation is required to confirm the exact role of iHD-SBRT and the optimal therapeutic sequence for the treatment of localized PDAC.

Inter-fraction heart displacement during voluntary deep inspiration breath hold radiation therapy without visual feedback measured by daily CBCT

Purpose/Objective

Deep Inspiration Breath Hold (DIBH) is now considered as the standard of care for many breast cancer patients. However, there are still uncertainties about the dose given to the heart, and it is unknown if patients may improve voluntary DIBH depth by gaining experience during treatment. In this study, we will examine the interfractional three-dimensional (3D) heart displacement throughout voluntary DIBH (vDIBH) radiotherapy by means of daily cone-beam computed tomography (CBCT).

Material and methods

Two hundred twenty-five unique CBCTs from 15 patients treated in 15 fractions were analyzed. During CBCT, a vDIBH was conducted without any visual feedback. Patients performed their DIBH freely after receiving explanations and training. After daily CBCT matching to the chest wall (CW), surface-guided radiation therapy (SGRT) tracked DIBH depth to ensure that the CW position was the same as the daily acquired CBCT. The CBCTs were retrospectively registered to the DIBH planning-CT to calculate daily changes in heart displacement relative to the CW.

Results

The mean displacement of the heart during DIBH treatment relative to the DIBH planning-CT was as follows: 1.1 mm to the right, interquartile range (IQR) 8.0; 0.5 mm superiorly, IQR 4.8; and 0 mm posteriorly, IQR 6.4. The Spearman correlation coefficients (r_s) were -0.15 (p=0.025), 0.04 (p=0.549), and 0.03 (p=0.612) for the X, Y, and Z directions, respectively. The differences in median heart displacement were significant: Friedmann rank sum test p=0.031 and pairwise comparison using the Wilcoxon rank-sum test were p=0.008 for X and Y; p=0.33 for X and Z; and p=0.07 for Y and Z. The total median heart motion was δ_{tot median}= 7.26 mm, IQR= 6.86 mm.

Conclusion

During DIBH, clinicians must be aware of the wide range of intra- and inter-individual heart position variations. The inter-individual heterogeneity shown in our study should be investigated further in order to avoid unexpected cardiac overexposure and to develop a more accurate heart dose-volume model.

Lymphocyte-sparing pelvic radiotherapy for prostate cancer: An in-silico study

•

Lymphocyte-sparing planning was developed for prostate cancer pelvic radiotherapy.

•

A significant dose reduction to the bone marrow was successfully demonstrated.

•

An Effective Dose to Immune Cells (EDIC) model was proposed for pelvic irradiation.

Background and Purpose

Evidence regarding radiation-induced lymphopenia and its negative impact on oncological outcome is incrementing. Therefore, the aim of this study is to evaluate the feasibility of lymphocyte-rich organs at risk (LOAR) sparing in pelvic irradiation for localized prostate cancer and to estimate its impact on the effective dose to circulating immune cells (EDIC).

Materials and Methods

Twenty patients with pelvic nodal and prostate or prostate bed irradiation were included. The following bone marrow (BM) structures were delineated as LOARs using semi-automatic segmentation: lumbosacral spine (Ls-BM), ilium (Il-BM), lower pelvis (Lp-BM), and the combined whole-pelvis (Wp-BM). Twenty new lymphocyte sparing treatment plans (LS plans) were calculated, optimizing doses to LOARs while maintaining strict coverage of the targets and respecting standard OARs dose constraints. Finally, we elaborated an EDIC calculation model for pelvic irradiation.

Results

LS plans showed a statistically significant dose decrease for LOAR compared to standard of care plans without compromising target coverage nor classic OAR dose constraints: in prostate plans, the V40Gy for Ls-BM, Il-BM, and Lp-BM was decreased by 23 %, 36 %, 52 % respectively. For prostate bed plans, the V40Gy for Ls-BM, Il-BM, and Lp-BM was decreased by 25 %, 59 %, 56 %, respectively. For Wp-BM, the V10Gy, V20Gy, and Dmean have been decreased by 3 %, 14 %, 15 %, and by 5 %, 15 %, 17 %, respectively for prostate and prostate bed plans. A statistically significant decrease in EDIC was seen for LS plans in both groups.

Conclusions

We successfully demonstrated the feasability of lympocyte-sparing treatment planning in pelvic irradiation, also proposing a model for EDIC calculation.

The State of the Art of Radiotherapy for Non-melanoma Skin Cancer: A Review of the Literature

Due to the general aging population and the fashion trend of sun exposure, non-melanoma skin cancer (NMSC) is rising. The management of NMSC is difficult and necessitates a multidisciplinary team (i.e., pathologists, dermatologists, medical oncologists, surgeons, and radiation oncologists). When surgery is not an option or will cause unacceptably functional morbidity, radiation therapy (RT) may be a preferable tissue-preserving option. Whether used alone or in conjunction with other treatments, RT has been shown to be quite effective in terms of cosmetic results and local control. Contact hypofractionated RT, brachytherapy, and electronic brachytherapy are all promising new treatments. However, rigorous, randomized trials are missing, explaining the disparity in dose, fractionation, and technique recommendations. Therefore, it is essential that interdisciplinary teams better understand RT modalities, benefits, and drawbacks. Our review will provide the role and indications for RT in patients with NMSC.

Qualitative evaluation of the role of RTTs IGRT specialists and their influence on treatment delivery

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Radiation Therapists specialised in image-guided radiation therapy (RTT spIGRT) experience their role positiveltly.

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The RTT spIGRT role is perceived to have a positive influence on radiotherapy treatment delivery.

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A legal framework to provide formal RTT training and continuous education in order to increase radiotherapy treatment quality is of utmost importance.

Purpose

The study aims to investigate qualitatively how Radiation Therapist IGRT specialists (RTT spIGRTs) experience their role and whether they have an impact on the treatment delivery.

Methods

Eleven RTTs, i.e. six RTT spIGRTs and five RTTs not specialised in IGRT (RTTs noIGRT) were interviewed during October and November 2020. RTTs noIGRT having knowledge of the daily practice before and after the creation of this RTT spIGRT role, served as control group capable of weighing its impact on the work environment. A qualitative method using face-to-face semi-structured questionnaires was used. Interviews lasted approximately 10–20 min, and were after coded and analysed for thematic content.

Results

Five themes and twelve sub-themes were drawn from the analysis. RTT spIGRTs experience their role positively, despite the limited role perception and different work experiences. The implemented role increased autonomy and facilitated decision-making and Radiotherapy (RT) treatment delivery.

Interviewees considered the new role useful to very useful. The raised concerns are related to a bigger role involvement and improvement, with focus on visibility, regular meetings and training. Interviewees considered the RTT spIGRT role to have an influence on the treatment delivery when properly carried out.

Conclusion

RTT spIGRTs experience their role positively. Their knowledge confidence seems to rely on the training received. The RTT spIGRT role is perceived to have a positive influence on the treatment delivery. Continuous follow up and training were amongst the suggested solutions to improve the RTT spIGRT’s role. This study stresses the urgent need for a legal framework to provide formal RTT training and continuous education in order to increase RT treatment quality.

Recent advances in radiosensitivity determinants in melanoma

PURPOSE OF REVIEW

Radiotherapy has been proven to be useful but insufficient in melanoma management due to the intrinsic radioresistance of melanoma cells. Elucidation of the molecular mechanisms and pathways related to resistance/sensitivity to radiotherapy in melanoma is of paramount importance. In this review, we will summarize and discuss the recent 'discoveries' and advances in radiosensitivity determinants in melanoma.

RECENT FINDINGS

The different levels of radiosensitivity among the various melanoma tumors could be attributed to the DNA damage signaling and repair proteins, tumor microenvironment, hypoxia, cell metabolism, glutathione and redox balance, protein kinase signaling pathways as well as pigmentation and melanin content.

SUMMARY

It is therapeutically important to elucidate the factors involved in radiation resistance/sensitivity of melanoma. More importantly, improving radiosensitivity may 'widen the clinical utility' in melanoma of this important therapeutic modality.

Clinical Outcomes After Proton Beam Therapy for Locally Advanced Non-Small Cell Lung Cancer: Analysis of a Multi-institutional Prospective Registry

Purpose

For most disease sites, level 1 evidence is lacking for proton beam therapy (PBT). By identifying target populations that would benefit most from PBT, prospective registries could overcome many of the challenges in clinical trial enrollment. Herein, we report clinical outcomes of patients treated with PBT for locally advanced non-small cell lung cancer (LA-NSCLC).

Methods and Materials

Data were obtained from the multi-institutional prospective database of the Proton Collaborative Group (PCG). Inclusion criteria of our study were stage III de novo or recurrent LA-NSCLC, use of PBT, and availability of follow-up data. Overall survival (OS) time was calculated from the start of treatment until death or last follow-up. Kaplan-Meier curves were generated for groups of interest and compared with log-rank tests. Cox regression modeling was used to evaluate the multivariate association between selected covariates and OS.

Results

A total of 195 patients were included in the analysis. PBT was given with a median equivalent dose in 2 Gy fractions (EQD2) of 63.8 Gy (relative biological effectiveness). Pencil beam scanning was used in 20% of treatments. Treatment-related grade 3 adverse events were rare: 1 pneumonitis, 2 dermatitis, and 3 esophagitis. No grade 4 events were reported. Two cardiac-related grade 5 events occurred in patients with multiple risk factors. The median follow-up time for living patients was 37.1 months and the median OS was 19.0 months. On multivariate analysis, good performance status (hazard ratio, 0.27; [95% confidence interval, 0.15-0.46]; P < .0001), pencil beam scanning use (0.55; [0.31-0.97]; P = .04), and increased EQD2 (0.80; [0.71-0.90] - per 10 Gy increase; P = .0002) were associated with decreased mortality.

Conclusions

PBT appears to yield low rates of adverse events with an OS similar to other retrospective studies on PBT for LA-NSCLC. PBS use and increased EQD2 can potentially improve OS.

Restoring p53 Function in Head and Neck Squamous Cell Carcinoma to Improve Treatments

TP53 mutation is one of the most frequent genetic alterations in head and neck squamous cell carcinoma (HNSCC) and results in an accumulation of p53 protein in tumor cells. This makes p53 an attractive target to improve HNSCC therapy by restoring the tumor suppressor activity of this protein. Therapeutic strategies targeting p53 in HNSCC can be divided into three categories related to three subtypes encompassing WT p53, mutated p53 and HPV-positive HNSCC. First, compounds targeting degradation or direct inhibition of WT p53, such as PM2, RITA, nutlin-3 and CH1iB, achieve p53 reactivation by affecting p53 inhibitors such as MDM2 and MDMX/4 or by preventing the breakdown of p53 by inhibiting the proteasomal complex. Second, compounds that directly affect mutated p53 by binding it and restoring the WT conformation and transcriptional activity (PRIMA-1, APR-246, COTI-2, CP-31398). Third, treatments that specifically affect HPV+ cancer cells by targeting the viral enzymes E6/E7 which are responsible for the breakdown of p53 such as Ad-E6/E7-As and bortezomib. In this review, we describe and discuss p53 regulation and its targeting in combination with existing therapies for HNSCC through a new classification of such cancers based on p53 mutation status and HPV infection.

Humanized Mice as a Valuable Pre-Clinical Model for Cancer Immunotherapy Research

Immunotherapy with checkpoint inhibitors opened new horizons in cancer treatment. Clinical trials for novel immunotherapies or unexplored combination regimens either need years of development or are simply impossible to perform like is the case in cancer patients with limited life expectancy. Thus, the need for preclinical models that rapidly and safely allow for a better understanding of underlying mechanisms, drug kinetics and toxicity leading to the selection of the best regimen to be translated into the clinic, is of high importance. Humanized mice that can bear both human immune system and human tumors, are increasingly used in recent preclinical immunotherapy studies and represent a remarkably unprecedented tool in this field. In this review, we describe, summarize, and discuss the recent advances of humanized mouse models used for cancer immunotherapy research and the challenges faced during their establishment. We also highlight the lack of preclinical studies using this model for radiotherapy-based research and argue that it can be a great asset to understand and answer many open questions around radiation therapy such as its presumed associated "abscopal effect".

Isotoxic high-dose stereotactic body radiotherapy integrated in a total multimodal neoadjuvant strategy for the treatment of localized pancreatic ductal adenocarcinoma

Background

Our aim was to evaluate the feasibility and safety of isotoxic high-dose (iHD) stereotactic body radiation therapy (SBRT) in a total neoadjuvant sequence for the treatment of localized pancreatic adenocarcinoma.

Materials and methods

Biopsy-proven borderline resectable/locally advanced pancreatic cancer (BR/LAPC) patients were included in this observational prospective analysis from August 2017 to April 2020 without excluding tumours showing a radiological direct gastrointestinal (GI) invasion. An induction chemotherapy by modified fluorouracil, irinotecan and oxaliplatin was performed for a median of six cycles. In case of non-progression, an isotoxic high-dose stereotactic body radiotherapy (iHD-SBRT) was delivered in 5 fractions followed by a surgical exploration. The primary endpoint was acute/late gastrointestinal grade ⩾3 toxicity. Secondary endpoints were overall survival (OS), progression-free survival (PFS) and local control (LC).

Results

A total of 39 consecutive patients (21 BR and 18 LAPC) were included: 34 patients (87.2%, 18 BR and 16 LAPC) completed the planned neoadjuvant sequence. After iHD-SBRT, 19 patients [55.9% overall, 13/18 BR (72.2%) and 6/16 LAPC (37.5%)] underwent an oncological resection among the 25 patients surgically explored (73.5%). The median follow up was 18.2 months. The rates of acute and late GI grade 3 toxicity were, respectively, 2.9% and 4.2%. The median OS and PFS from diagnosis were, respectively, 24.5 and 15.6 months. The resected patients had improved median OS and PFS in comparison with the non-resected patients (OS: 32.3 versus 18.2 months, p = 0.02; PFS: 24.1 versus 7.1 months, p < 0.001). There was no survival difference between the BR and LAPC patients. The 1-year LC from SBRT was 74.1% and the median locoregional PFS was not reached for both BR and LAPC patients.

Conclusions

iHD-SBRT displays an excellent toxicity profile, also for potentially high-risk patients with radiological direct GI invasion at diagnosis and can be easily integrated in a total neoadjuvant strategy. The oncological outcomes are promising and emphasise the need for further exploration of iHD-SBRT in phase II/III trials.

Unintended dose to the lower axilla in adjuvant radiotherapy for breast cancer: Differences between tangential beam and VMAT

BACKGROUND AND PURPOSE

To evaluate dosimetric differences in unintended dose to the lower axilla between 3D-standard (3DCRT), tangential beam forward intensity modulated radiotherapy (F-IMRT) and volumetric modulated arc therapy (VMAT). The objective is to evaluate whether results of clinical trials, such as the ACOSOG-Z011 trial, that evaluated omission of axillary clearance can be extrapolated towards more conformal techniques like VMAT.

MATERIALS AND METHODS

Twenty-five consecutive patients treated with whole breast radiotherapy alone (WBRT) using a F-IMRT technique were identified. Three additional plans were created for every patient: one plan using a single 270° arc (VMAT 1x270°), another using two small ≤90° opposing arcs (VMAT 2x < 90°) and thirdly a 3DCRT plan without F-IMRT. Axillary levels I-II were contoured after the treatment plans were made.

RESULTS

The volume of the axilla level I that was covered by the 50% isodose (V50%) was significantly higher for VMAT 2x < 90° (71.3 cm³, 84% of structure volume, p < 0.001) and VMAT 1x270° (68.8 cm³, 81%, p < 0.01) compared to 3DCRT (60.3 cm³, 71%) and F-IMRT (60.8 cm³, 72%). The V50% to the axilla level II, however, was low for all techniques: 12.3 cm³ (12%); 8.9 cm³ (9%); 4.3 cm³ (4%); 4.4 cm³ (4%) for VMAT 2x < 90°, VMAT 1x270°, 3DCRT, F-IMRT, respectively. For the higher doses (V90% and above), no clinically relevant differences were seen between the different modalities.

CONCLUSION

WBRT treatments with VMAT do not lead to a significant reduction of the unintended axillary dose in comparison with a tangential beam setup. Hence, concerning tumor control, VMAT can be applied to clinical situations similar to the Z0011 trial. The intermediate axillary dose is higher with VMAT, but the clinical consequence of this difference on toxicity is unknown.

Oligometastatic Disease Detection with 68Ga-PSMA-11 PET/CT in Hormone-Sensitive Prostate Cancer Patients (HSPC) with Biochemical Recurrence after Radical Prostatectomy: Predictive Factors and Clinical Impact

Metastasis-directed therapy (MDT) in oligometastatic prostate cancer has the potential of delaying the start of androgen deprivation therapy (ADT) and disease progression. We aimed to analyze the efficacy of PSMA-PET/CT in detecting oligometastatic disease (OMD), to look for predictive factors of OMD, and to evaluate the impact of PSMA-PET/CT findings on clinical management. We retrospectively analyzed a homogeneous population of 196 hormone-sensitive prostate cancer patients (HSPC), considered potential candidates for MDT, with a PSMA-PET/CT performed at biochemical recurrence (BCR) after radical prostatectomy (RP). Multivariable logistic regression analysis was performed based on several clinico-pathological factors. Changes in clinical management before and after PSMA-PET/CT were analyzed. The OMD detection rate was 44% for a total positivity rate of 60%. PSMA-PET/CT positivity was independently related to PSA (OR (95% CI), p) (1.7 (1.3-2.3), p < 0.0001) and PSAdt (0.4 (0.2-0.8), p = 0.013), and OMD detection was independently related to PSA (1.6 (1.2-2.2), p = 0.001) and no previous salvage therapy (0.3 (0.1-0.9), p = 0.038). A treatment change was observed in 58% of patients, mostly to perform MDT after OMD detection (60% of changes). This study showed that PSMA-PET/CT is an excellent imaging technique to detect OMD early in HSPC patients with BCR after RP, changing therapeutic management mostly into MDT.

Assessment of cough in head and neck cancer patients at risk for dysphagia-An overview

BACKGROUND

This literature review explores the terminology, the neurophysiology, and the assessment of cough in general, in the framework of dysphagia and regarding head and neck cancer patients at risk for dysphagia. In the dysphagic population, cough is currently assessed perceptually during a clinical swallowing evaluation or aerodynamically.

RECENT FINDINGS

Recent findings have shown intra and inter-rater disagreements regarding perceptual scoring of cough. Also, aerodynamic measurements are impractical in a routine bedside assessment. Coughing, however, is considered to be a clinically relevant sign of aspiration and dysphagia in head and cancer patients treated with concurrent chemoradiotherapy.

CONCLUSION

This article surveys the literature regarding the established cough assessment and stresses the need to implement innovative methods for assessing cough in head and neck cancer patients treated with concurrent chemoradiotherapy at risk for dysphagia.

Neo-CheckRay: radiation therapy and adenosine pathway blockade to increase benefit of immuno-chemotherapy in early stage luminal B breast cancer, a randomized phase II trial

BACKGROUND

Residual breast cancer after neo-adjuvant chemotherapy (NACT) predicts disease outcome and is a surrogate for survival in aggressive breast cancer (BC) subtypes. Pathological complete response (pCR) rate, however, is lower for luminal B BC in comparison to the triple negative (TNBC) and HER2+ subtypes. The addition of immune checkpoint blockade (ICB) to NACT has the potential to increase pCR rate but is hampered by the lower immunogenicity of luminal B BC. Novel strategies are needed to stimulate the immune response and increase the response rate to ICB in luminal B BC.

METHODS

The Neo-CheckRay trial is a randomized phase II trial investigating the impact of stereotactic body radiation therapy (SBRT) to the primary breast tumor in combination with an anti-CD73 (oleclumab) to increase response to anti PD-L1 (durvalumab) and NACT. The trial is designed as a three-arm study: NACT + SBRT +/- durvalumab +/- oleclumab. The result at surgery will be evaluated using the residual cancer burden (RCB) index as the primary endpoint. Six patients will be included in a safety run-in, followed by a randomized phase II trial that will include 136 evaluable patients in 3 arms. Inclusion is limited to luminal B breast cancers that are MammaPrint genomic high risk.

DISCUSSION

combination of ICB with chemotherapy in luminal B BC might benefit from immune priming agents to increase the response rate. As none have been identified so far, this phase II trial will evaluate SBRT and oleclumab as potential immune priming candidates.

TRIAL REGISTRATION

trial registered on ClinicalTrials.gov ( NCT03875573 ) on March 14th, 2019.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Checkpoint inhibition in combination with an immunoboost of external beam radiotherapy in solid tumors (CHEERS): study protocol for a phase 2, open-label, randomized controlled trial

BACKGROUND

While the introduction of checkpoint inhibitors (CPIs) as standard of care treatment for various tumor types has led to considerable improvements in clinical outcome, the majority of patients still fail to respond. Preclinical data suggest that stereotactic body radiotherapy (SBRT) could work synergistically with CPIs by acting as an in situ cancer vaccine, thus potentially increasing response rates and prolonging disease control. Though SBRT administered concurrently with CPIs has been shown to be safe, evidence of its efficacy from large randomized trials is still lacking. The aim of this multicenter randomized phase II trial is to assess whether SBRT administered concurrently with CPIs could prolong progression-free survival as compared to standard of care in patients with advanced solid tumors.

METHODS/DESIGN

Ninety-eight patients with locally advanced or metastatic disease will be randomized in a 1:1 fashion to receive CPI treatment combined with SBRT (Arm A) or CPI monotherapy (Arm B). Randomization will be stratified according to tumor histology (melanoma, renal, urothelial, head and neck squamous cell or non-small cell lung carcinoma) and disease burden (≤ or > 3 cancer lesions). The recommended SBRT dose is 24Gy in 3 fractions, which will be administered to a maximum of 3 lesions and is to be completed prior to the second or third CPI cycle (depending on CPI treatment schedule). The study's primary endpoint is progression-free survival as per iRECIST. Secondary endpoints include overall survival, objective response, local control, quality of life and toxicity. Translational analyses will be performed using blood, fecal and tissue samples.

DISCUSSION

The CHEERS trial will provide further insights into the clinical and immunological impact of SBRT when combined with CPIs in patients with advanced solid tumors. Furthermore, study results will inform the design of future immuno-radiotherapy trials.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT03511391 . Registered 17 April 2018.

Split-VMAT technique to control the deep inspiration breath hold time for breast cancer radiotherapy

BACKGROUND

To improve split-VMAT technique by optimizing treatment delivery time for deep-inspiration breath hold (DIBH) radiotherapy in left-sided breast cancer patients, when automatic beam-interruption devices are not available.

METHODS

Ten consecutive patients were treated with an eight partial arcs (8paVMAT) plan, standard of care in our center. A four partial arcs (4paVMAT) plan was also created and actual LINAC outputs were measured, to evaluate whether there was a dosimetric difference between both techniques and potential impact on the delivered dose. Subsequently, ten other patients were consecutively treated with a 4paVMAT plan to compare the actual treatment delivery time between both techniques. The prescribed dose was 40.05 Gy/15 fractions on the PTV breast (breast or thoracic wall), lymph nodes (LN) and intramammary lymph node chain (IMN). Treatment delivery time, PTVs coverage, conformity index (CI), organs at risk (OAR) dose, monitor units (MU), and gamma index were compared.

RESULTS

Both split-VMAT techniques resulted in similar dose coverage for the PTV Breast and LN, and similar CI. For PTV IMN we observed a 5% increased coverage for the volume receiving ≥ 36 Gy with 4paVMAT, with an identical volume receiving ≥ 32 Gy. There was no difference for the OAR sparing, with the exception of the contralateral organs: there was a 0.6 Gy decrease for contralateral breast mean (p ≤ 0.01) and 1% decrease for the volume of right lung receiving ≥ 5 Gy (p = 0.024). Overall, these results indicate a modest clinical benefit of using 4paVMAT in comparison to 8paVMAT. An increase in the number of MU per arc was observed for the 4paVMAT technique, as expected, while the total number of MU remained comparable for both techniques. All the plans were measured with the Delta4 phantom and passed the gamma index criteria with no significant differences. Finally, the main difference was seen for the treatment delivery time: there was a significant decrease from 8.9 to 5.4 min for the 4paVMAT plans (p < .05).

CONCLUSIONS

This study is mainly of interest for centers who are implementing the DIBH technique without automatic beam-holding devices and who therefore may require to manually switch the beam on and off during breast DIBH treatment. Split-VMAT technique with 4 partial arcs significantly reduces the treatment delivery time compared to 8 partial arcs, without compromising the target coverage and the OAR sparing. The technique decreases the number of breath holds per fraction, resulting in a shorter treatment session.

Evaluation of the XVI dual registration tool for image-guided radiotherapy in prostate cancer

Purpose

To compare the reliability and the required time for two cone-beam CT (CBCT) registration methods for prostate irradiation (PI) and prostate bed irradiation (PBI).

Material and methods

Two-hundred treatment fractions (in 10 PI and 10 PBI patients) were reanalyzed, using two CBCT registration methods: (1) a combination of an automated chamfer matching (CM) with manual matching (MM), and (2) the automated XVI dual registration tool (DRT). Bland-Altman 95% Limits of Agreement (LoA) were used to assess agreement with manual registration by Radiation Oncologists.

Results

All 95% LoA for CM + MM were ≤ 0.33 cm. For DRT, several 95% LoA were notably larger than the predefined clinical threshold of 0.3 cm: -0.47 to +0.25 cm (PI) and -0.36 to +0.23 cm (PBI) for the superior-inferior direction and -0.52 to +0.24 cm (PI) and -0.38 to +0.31 cm (PBI) for the anterior-posterior direction.For PI, the average time required was 33 s with CM + MM versus only 18 s with DRT (p = 0.002). For PBI, this was 13 versus 19 s, respectively (p = 0.16).

Conclusion

For PI, DRT was significantly faster than CM + MM, but the accuracy is insufficient to use without manual verification. Therefore, manual verification is still warranted, but could offset the time benefit. For PBI, the CM + MM method was faster and more accurate.

Preoperative and postoperative radiotherapy (RT) for non-small cell lung cancer: still an open question

Preoperative and postoperative radiotherapy (PORT) with or without chemotherapy has been used in non-small cell lung cancer (NSCLC) for decades. Numerous trials have investigated the potential survival benefit of this strategy, but despite greater knowledge of the disease, considerable technological developments in imaging and radiotherapy, and significant progress in surgery, many questions remain unsolved. In this review, we summarize the current knowledge on this problem and discuss issues which still require elucidation.

Impact of the COVID-19 Pandemic on Patients and Staff in Radiation Oncology Departments in Belgium: A National Survey

Purpose: COVID-19 reached Belgium in February and quickly became a major public health challenge. It is of importance to evaluate the actual impact of COVID-19 on patients and staff in Belgian radiotherapy departments (RTDs). This was evaluated through a weekly national survey sent to departments measuring key factors that were affected by the pandemic.

Materials and Methods: The Belgian SocieTy for Radiation Oncology (BeSTRO) together with the Belgian College for physicians in Radiation Oncology invited all 26 RTD to participate in a survey that started on March 2nd and was re- submitted weekly for 4 months to assess variations in time. The survey focused on: (1) the COVID-19 status of patients and staff; (2) the management of clinically suspected COVID patients and COVID positive patients; (3) the impact of COVID-19 on RTD activities; (4) its impact in radiotherapy indications and fractionation schemes.

Results: Seventy-three percent of 26 RTDs completed the first survey and 57% responded to all weekly surveys. In the RTD staff, 24 members were COVID-positive of whom 67% were RTTs. Over the study period, the number of patients treated dropped by a maximum of 18.8% when compared to March 2nd. In 32.3% of COVID-positive and 54% of COVID suspected patients, treatment was continued without any interruptions. Radiotherapy indications were adapted within the 1st weeks of the survey in 47.4% of RTD, especially for urological and breast tumors. Fractionation schemes were changed in 68.4% of RTD, mainly for urological, breast, gastro-intestinal, and lung tumors.

Conclusions: Between March and June 2020, the COVID-19 pandemic resulted in an important decrease in treatment activity in RTD in Belgium (18.8%). The COVID-19 infection status of patients influenced the continuity of the radiotherapy schedule. Changes in indications and fractionation schedules of radiotherapy were rapidly incorporated in the different RTD.

Successful treatment of synchronous chemoresistant pulmonary metastasis from pleomorphic rhabdomyosarcoma with stereotaxic body radiation therapy: A case report and a review of the literature

BACKGROUND

Rhabdomyosarcoma (RMS) is a highly malignant soft tissue sarcoma (STS), usually of adults, displaying skeletal muscle differentiation. STS principally metastasize to the lungs with more than 50% of metastatic patients presenting with isolated pulmonary metastasis. Paradoxically, the majority of drugs prescribed to treat RMS are associated with multidrug resistance.

CASE REPORT

We report the case of a 53 year-old patient who developed three synchronous chemoresistant lung metastasis from pleomorphic RMS. Considering the poor prognosis, the patient's preference and the chemoresistance of her lung metastasis, we decided to perform two consecutive stereotactic body radiotherapy (SBRT) on two of these three lesions.

DISCUSSION

Initially, the patient was referred to our institute with a painful mass in the anterior part of the left thigh increasing in volume for 3 months. Biopsy revealed a high-grade pleomorphic RMS. The cancer being staged IB, she had neoadjuvant radiotherapy. After complete surgical excision, pathology examination revealed a 6 cm Grade II pleomorphic RMS, with clear margins. Six months later, she developed three synchronous lung metastases. She got 4 courses of doxorubicin-ifosfamide which were poorly supported. After two courses, a heterogeneous (morphological and metabolic) response was observed, hence SBRT was delivered with a Biologically Equivalent Dose (α/β10)> 100 Gray on the two more chemoresistant lesions. This SBRT was very well tolerated, no side effects were reported. The patient remained alive and achieved a complete response of these three metastases, which sustains after more than 3 years.

CONCLUSION

Early recognition and proper management of these oligometastatic patients may lead to motivating results in a poor prognosis disease.

Meta-Analysis on Induction Chemotherapy in Locally Advanced Nasopharyngeal Carcinoma

Purpose

Concurrent chemo radiotherapy (CCRT) has been the standard of care in locally advanced nasopharyngeal carcinoma (LA‐NPC) for many years. The role of induction chemotherapy (ICT) has always been controversial. This systematic review and meta‐analysis investigates the value of adding ICT to CCRT in LA‐NPC.

Materials and Methods

Two reviewers independently assessed the eligibility of randomized controlled trials (RCTs) comparing ICT followed by CCRT versus CCRT alone, including treatment‐naive adult patients with histologically proven nonmetastatic LA‐NPC.

Results

Eight RCTs with in total 2,384 randomized patients, of whom 69% had N2–N3 disease, were selected. ICT was the allocated treatment in 1,200 patients, of whom 1,161 actually received this. Treatment compliance varied, with a median rate of 92% (range, 86%–100%) of patients receiving all cycles of ICT. The percentage of patients completing radiotherapy was 96% and 95% [(Combined Risk difference(CRD)= 0.004; 95% Confidence Interval (CI) –0.001–0.01; p = 0.14)] in the ICT group and CCRT group, respectively, whereas chemotherapy during radiotherapy could be completed in only 28% of the ICT group versus 61% in the CCRT group (CRD, −0.243; 95% CI, −0.403 to −0.083; p = .003). Grade 3–4 acute toxicity was mostly hematologic during the ICT phase (496 events vs. 191 nonhematologic) and was predominant in the ICT group (1,596 events vs. 1,073 in the CCRT alone group) during the CCRT. Adding ICT to CCRT provided a significant benefit in overall survival (hazard ratio [HR], 0.680; 95% CI, 0.511–0.905; p = .001) and progression‐free survival (HR, 0.657; 95% CI, 0.568–0.760; p < .001).

Conclusion

Although ICT followed by CCRT is associated with more acute toxicity and a lower compliance of the chemotherapy during the CCRT phase, this association resulted in a clinically meaningful survival benefit. ICT should be considered as a standard option in patients with LA‐NPC, but further study on optimal patient selection for this treatment is warranted.

Implications for Practice

Locally advanced nasopharyngeal carcinoma (LA‐NPC) is a relatively common disease in some parts of the world, with a rather poor prognosis due to its high metastatic potential. The role of induction chemotherapy (ICT) has always been controversial. This meta‐analysis found that ICT followed by concurrent chemoradiotherapy (CCRT) in LA‐NPC is associated with a significant clinical improvement in both overall survival and progression‐free survival compared with CCRT alone. ICT should be considered as a standard option in patients with LA‐NPC.

This review reports on the role of induction chemotherapy in locally advanced nasopharyngeal carcinoma, focusing on the effect of adding induction chemotherapy to concurrent chemoradiotherapy on overall and progression‐free survival.

Brachytherapy in Belgium in 2018. A national survey of the brachytherapy study group of the Belgian SocieTy for Radiotherapy and Oncology (BeSTRO)

PURPOSE

To explore the current practices patterns and evaluate the actual brachytherapy (BT) resources in Belgium.

MATERIAL AND METHODS

In 2019, the Brachytherapy Study Group proposed to conduct a survey on behalf of the Belgian SocieTy of Radiation Oncology (BeSTRO) in order to identify current BT practice patterns. An electronic questionnaire was sent to all primary radiotherapy centers in Belgium. This questionnaire was based on the questionnaire that was used by the Italian Association of Radiation Oncology (AIRO) in 2016, asking for: (a) General information on the Radiation Oncology Centre; (b) BT equipment and human resources; (c) BT procedures; (d) BT assessment (number of patients treated annually, treated sites, and different modalities of treatments).

RESULTS

All 24 radiation oncology centers (100% response rate) answered the questionnaire and gave also information on the performance of brachytherapy in their (eventual) satellite centers. Eighteen (18) BT afterloader units were installed and operational in 2018. Thirteen centers mentioned a prostate seed implant program, one center a prostate and eye plaque program and one center only an eye plaque program. Less than 50% of centers have the infrastructure to offer the full-range of BT in their own department. In 2018, 1486 patients received a BT-treatment, 28% of them were treated by prostate seed implant, 8% were treated by eye-(seed) BT and 64% by high dose rate (HDR)/pulsed dose rate (PDR) BT. Forty-five percent of HDR/PDR patients were treated by vaginal dome BT, 22% by intra-uterine BT, 11% by skin BT, 10% by breast BT (almost exclusively in one centre), 8% for benign pathology (keloid) and the remaining 4% were treated for prostate (as a boost or as salvage in one centre), anal, penile, lung or oesophageal cancer.

CONCLUSIONS

Belgian radiotherapy departments often perform BT only in a (highly) selected group of pathologies, resulting in a limited number of patients treated by this technique despite the sufficient availability of BT equipment. Modern indications are often not covered, hence patients do not have regular access to recognized treatment options, possibly leading to inferior oncological outcome. BeSTRO will use the results of this survey to stimulate improvements in training, awareness, education, implementation, collaboration and cooperation in the field of brachytherapy.

Novel strategies using modern radiotherapy to improve pancreatic cancer outcomes: toward a new standard?

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most aggressive solid tumours with an estimated 5-year overall survival rate of 7% for all stages combined. In this highly resistant disease that is located in the vicinity of many radiosensitive organs, the role of radiotherapy (RT) and indications for its use in this setting have been debated for a long time and are still under investigation. Although a survival benefit has yet to be clearly demonstrated for RT, it is the only technique, other than surgery, that has been demonstrated to lead to local control improvement. The adjuvant approach is now strongly challenged by neoadjuvant treatments that could spare patients with rapidly progressive systemic disease from unnecessary surgery and may increase free margin (R0) resection rates for those eligible for surgery. Recently developed dose-escalated RT treatments, designed either to maintain full-dose chemotherapy or to deliver a high biologically effective dose, particularly to areas of contact between the tumour and blood vessels, such as hypofractionated ablative RT (HFA-RT) or stereotactic body RT (SBRT), are progressively changing the treatment landscape. These modern strategies are currently being tested in prospective clinical trials with encouraging preliminary results, paving the way for more effective treatment combinations using novel targeted therapies. This review summarizes the current literature regarding the use of RT for the treatment of primary PDAC, describes the limitations of conventional RT, and discusses the emerging role of dose-escalated RT and heavy-particle RT.

Follow-Up of Head and Neck Cancer Survivors: Tipping the Balance of Intensity

The traditional concept of post-treatment surveillance in head and neck cancer patients relies on examinations directed at early detection of disease recurrence and/or second primary tumors. They are usually provided by ear, nose and throat specialists with complementary input from radiation oncologists and medical oncologists. Emerging evidence underscores the importance of monitoring and effective management of late adverse events. One of the major drawbacks is a lack of prospective controlled data. As a result, local institutional policies differ, and practice recommendations are subject to continuing debate. Due to the economic burden and impact on emotional comfort of patients, intensity and content of follow-up visits are a particularly conflicting topic. According to the current evidence-based medicine, follow-up of head and neck cancer patients does not prolong survival but can improve quality of life. Therefore, an approach giving priority to a multidisciplinary care involving a speech and swallowing expert, dietician, dentist, and psychologist may indeed be more relevant. Moreover, on a case-by-case basis, some patients need more frequent consultations supplemented by imaging modalities. Human papillomavirus positive oropharyngeal cancer tends to develop late failures at distant sites, and asymptomatic oligometastatic disease, especially in the lungs, can be successfully salvaged by local ablation, either surgically or by radiation. The deep structures of the skull base related to the nasopharynx are inaccessible to routine clinical examination, advocating periodic imaging supplemented by nasofibroscopy as indicated. Anamnesis of heavy smoking justifies annual low-dose computed tomography screening of the thorax and intensive smoking cessation counseling. Finally, some cancer survivors feel more comfortable with regular imaging, and their voice should be taken into consideration. Future development of surveillance strategies will depend on several variables including identification of reliable predictive factors to select those who could derive the most benefit from follow-up visits, the availability of long-term follow-up data, the results of the first randomized trials, resource allocation patterns, infrastructure density, and the therapeutic landscape of locally advanced and recurrent and/or metastatic disease, which is rapidly changing with the advent of immune checkpoint inhibitors and better utilization of local approaches.

Radiotherapy Quality Assurance for Head and Neck Squamous Cell Carcinoma

The impact of radiotherapy (RT) quality assurance (QA) has been demonstrated by numerous studies and is particularly important for head and neck cancer (HNC) treatment due to the complexity of RT target volumes in this region and the multiple adjacent organs at risk. The RT planning process includes many critical steps including interpretation of diagnostic imaging, image fusion, target volume delineation (tumor, lymph nodes, and organs at risk), and planning. Each step has become highly complex, and precise and rigorous QA throughout the planning process is essential. The ultimate aim is to precisely deliver radiation dose to the target, maximizing the tumor dose and minimizing the dose to surrounding organs at risk, in order to improve the therapeutic index. It is imperative that RT QA programs should systematically control all aspects of the RT planning pathway and include regular end-to-end tests and external audits. However, comprehensive QA should not be limited to RT and should, where possible, also be implemented for surgery, systemic therapy, pathology, as well as other aspects involved in the interdisciplinary treatment of HNC.

Prognostic impact of glioblastoma stem cell markers OLIG2 and CCND2

Aims

Glioblastoma (GBM) is the most common and lethal malignant brain tumor in adults. Glioma stem cells (GSCs) are implicated in this poor prognosis and in radio(chemo‐)resistance. We have previously demonstrated that among potentially highly specific GSC markers oligodendrocyte lineage transcription factor 2 (OLIG2) appears to be the most specific and cyclin D2 (CCND2) the only one related to cell cycle regulation. The purpose of this work was to investigate the clinical significance and the evolution of OLIG2 and CCND2 protein expression in GBM.

Methods and results

Immunohistochemical expression analysis of Olig2 and Ccnd2 was carried out on a cohort of human paired GBM samples comparing initial resections with local recurrent tumors after radiation therapy (RT) alone or radio‐chemotherapy with temozolomide (RT‐TMZ). Uni‐ and multivariate logistic regression analysis revealed that significant risk factors predicting early mortality (<12 months) are: subtotal surgery for recurrence, time to recurrence <6 months, Ccnd2 nuclear expression at initial surgery ≥30%, and Olig2 nuclear expression <30% at second surgery after RT alone and RT‐TMZ.

Conclusions

We demonstrated that patients for whom nuclear expression of Olig2 becomes low (<30%) after adjuvant treatments have a significantly shorter time to recurrence and survival reflecting most probably a proneural to mesenchymal transition of the GSCs population. We also highlighted the fact that at initial surgery, high nuclear expression (≥30%) of CCND2, a G1/S regulator specific of GSCs, has a prognostic value and is associated with early mortality (<12 months).

The Benefit of Reactivating p53 under MAPK Inhibition on the Efficacy of Radiotherapy in Melanoma

Radiotherapy (RT) in patients with melanoma historically showed suboptimal results, because the disease is often radioresistant due to various mechanisms such as scavenging free radicals by thiols, pigmentary machinery, or enhanced DNA repair. However, radiotherapy has been utilized as adjuvant therapy after the complete excision of primary melanoma and lymph nodes to reduce the rate of nodal recurrences in high-risk patients. The resistance of melanoma cells to radiotherapy may also be in relation with the constitutive activation of the MAPK pathway and/or with the inactivation of p53 observed in about 90% of melanomas. In this study, we aimed to assess the potential benefit of adding RT to BRAF-mutated melanoma cells under a combined p53 reactivation and MAPK inhibition in vitro and in a preclinical animal model. We found that the combination of BRAF inhibition (vemurafenib, which completely shuts down the MAPK pathway), together with p53 reactivation (PRIMA-1Met) significantly enhanced the radiosensitivity of BRAF-mutant melanoma cells. This was accompanied by an increase in both p53 expression and activity. Of note, we found that radiation alone markedly promoted both ERK and AKT phosphorylation, thus contributing to radioresistance. The combination of vemurafenib and PRIMA-1Met caused the inactivation of both MAPK kinase and PI3K/AKT pathways. Furthermore, when combined with radiotherapy, it was able to significantly enhance melanoma cell radiosensitivity. Interestingly, in nude mice bearing melanoma xenografts, the latter triple combination had not only a synergistic effect on tumor growth inhibition, but also a potent control on tumor regrowth in all animals after finishing the triple combination therapy. RT alone had only a weak effect. In conclusion, we provide a basis for a strategy that may overcome the radioresistance of BRAF-mutated melanoma cells to radiotherapy. Whether this will translate into a rational to use radiotherapy in the curative setting in BRAF-mutated melanoma patients deserves consideration.

Low-Dose vs. High-Dose Cisplatin: Lessons Learned From 59 Chemoradiotherapy Trials in Head and Neck Cancer

In locally advanced squamous cell carcinomas of the head and neck (LA-SCCHN), concurrent chemoradiotherapy is an integral part of multimodality management both in the adjuvant and in the definitive settings. Although de-intensification strategies have been propelled to the forefront of clinical research in human papillomavirus (HPV) positive oropharyngeal cancer, three cycles of 100 mg/m² cisplatin given every 3 weeks concurrently with conventionally fractionated external beam radiotherapy represent a cost-effective and globally accessible treatment option for the majority of LA-SCCHN cases. Based on four large randomized trials, this regimen has become the non-surgical standard of care for cisplatin-eligible patients. Nevertheless, the outcomes in terms of efficacy, toxicity, and compliance have been rather disappointing. Therefore, there is an unmet need to find a better alternative. With limited support from randomized trials, weekly low-dose cisplatin regimens have replaced the standard high-dose schedule at some institutions. Four prospective trials exploring radiotherapy with and without weekly low-dose cisplatin have been published. Two of them were conducted in the 1980s, one of which had a negative outcome, the third study provided insufficient information on toxicity, and the fourth trial had to be prematurely terminated due to poor accrual. Moreover, the findings of two phase III trials comparing the two concurrent cisplatin regimens favored the high-dose protocol. We performed a composite meta-analysis of 59 prospective trials enrolling a total of 5,582 patients. The primary endpoint was overall survival. Reflecting different radiotherapy fractionation schemes and treatment intents, three meta-analyses were carried out, one for postoperative conventional chemoradiotherapy, one for definitive conventional chemoradiotherapy, and one for definitive altered fractionation chemoradiotherapy. In the former two settings, both high- and low-dose regimens yielded similar survival outcomes, thus, the primary objective was not met. When given concurrently with altered fractionation radiotherapy, patients treated with high-dose cisplatin had significantly longer overall survival than those who received low-dose cisplatin. In this article we provide a synthetic view of the results, discuss the issue of cumulative dose, compare two vs. three cycles of high-dose cisplatin, and present our three-step recommendations for use of the current standard of care, high-dose cisplatin, in clinical practice.

Dose-response in choroidal melanoma

PURPOSE

In choroidal melanoma the radiation threshold dose for local control remains largely unknown. The present study examined a group of patients that received a wide range of minimum tumor dose in order to investigate a dose-response relationship. A literature review is performed to compare our results with available evidence in brachytherapy and charged particle external beam radiotherapy.

MATERIALS AND METHODS

A retrospective study was conducted on all choroidal melanomas treated with Strontium-90 (Sr-90) at the University Hospital of Leuven between 1983 and 2012. Local failure was defined as primary endpoint and was estimated according to the competing risk method.

RESULTS

In 135 patients, the minimum tumor dose (Dmin) ranged from 0 Gy to 287 Gy (median: 27.6 Gy). Multivariable analysis revealed Dmin ≥ 65 Gy (p = 0.04; HR = 0.09) and tumor distant from the optic disc (p < 0.001, HR = 0.09) to be independent variables favoring local control. The scleral dose, the tumor diameter and tumor height did not significantly affect local failure in multivariate analysis.

CONCLUSION

This is the first study to examine a group of patients treated with a Dmin ranging from 0 Gy to >250 Gy. Treatment with a Dmin of 65 Gy is necessary to achieve durable tumor response. The dose-response data provided by our study could be used for the design of future trials examining the ideal dose for the treatment of choroidal melanoma with brachytherapy or charged particle external beam radiotherapy.

Unusual presentation of a hepatocellular carcinoma as a potential late side effect of radiotherapy in a patient treated for Wilms tumor in childhood

Background

The development of a second primary tumor is a potential late side effect of radiotherapy. Particularly, an increased risk of secondary cancers, mostly of digestive or breast origin, has been observed in patients treated with high-dose radiotherapy for Wilms tumor (WT) in childhood. However, hepatocellular carcinoma (HCC) has been very rarely described as a potentially radiotherapy-induced tumor. We describe the case of a patient with an aggressive HCC 50 years after the treatment of a WT.

Case presentation

A 49-year old man, treated at the age of 6 weeks for a right WT by a right nephrectomy and adjuvant radiotherapy, presented with a right abdominal mass. Imaging demonstrated a 100-mm tumor invading the inferior segment of the right liver, the right colon and the right psoas muscle. The patient had no previous history of liver disease, nor of alcohol consumption, and hepatitis serologies were negatives. Biopsy demonstrated a poorly differentiated tumor of unknown origin. A panel of tumor markers was negative. Explorative surgery has been performed allowing en bloc R0 tumor resection, including resection of segments VI and VII of the liver, right hemicolectomy and resection of the anterior sheet of the right psoas muscle. Pathological examination revealed a poorly differentiated HCC. No signs of cirrhosis or chronic liver disease were observed in the non-tumor liver. Twenty weeks after surgery, the patient developed a multifocal tumor recurrence that was treated with intra-arterial ⁹⁰Yttrium radioembolization.

Conclusion

In this case, the absence of risk factors for HCC, such as cirrhosis, viral hepatitis and chronic liver disease, highly suggests the development of HCC to be related to previous high-dose radiation therapy given for a right WT to a field involving the inferior part of the liver. This observation shows radiotherapy to/near the liver, particularly in childhood, to be a potential risk factor for HCC, stressing the need for a long-term specific follow-up in patients irradiated in childhood.

The Outcome of the First 100 Nasopharyngeal Cancer Patients in Thailand Treated by Helical Tomotherapy

Background

The aim of the study was to analyse of two-year loco-regional failure free survival (LRFFS), distant metastasis free survival (DMFS), overall survival (OS), and toxicity outcomes of the first 100 nasopharyngeal carcinoma patients in Thailand treated by helical tomotherapy.

Patients and methods

Between March 2012 and December 2015, 100 patients with non-metastatic nasopharyngeal carcinoma were treated by helical tomotherapy. All patients were treated by platinum-based concurrent chemoradiotherapy and adjuvant or neo-adjuvant chemotherapy.

Results

The median age was 51 years (interquartile ranges [IQR]: 42.5–57.0). The mean ± SD of D95% of planning target volume (PTV) 70, 59.4 and 54 were 70.2 ± 0.5, 59.8 ± 0.6, and 54.3 ± 0.8 Gy, respectively. The mean ± SD of conformity index, and homogeneity index were 0.89 ± 0.13 and 0.06 ± 0.07. Mean ± SD of D2 % of spinal cord and brainstem were 34.1 ± 4.4 and 53.3 ±6.3 Gy. Mean ± SD of D50 of contralateral and ipsilateral parotid gland were 28.4 ± 6.7 and 38.5 ± 11.2 Gy. At a median follow-up of 33 months (IQR: 25–41), the 2-year LRFFS, DMFS, OS were 94% (95%CI: 87–98%), 96% (95% CI: 89–98%), and 99% (95% CI: 93–100%), respectively. Acute grade 3 dermatitis, pharyngoesophagitis, and mucositis occurred in 5%, 51%, and 37%, respectively. Late pharyngoesophagitis grade 0 and 1 were found in 98% and 2% of patients. Late xerostomia grade 0, 1 and 2 were found in 17%, 78% and 5%, respectively.

Conclusions

Helical tomotherapy offers good dosimetric performance and achieves excellent treatment outcome in nasopharyngeal carcinoma patients.