Mature results of an individualized radiation dose prescription study based on normal tissue constraints in stages I to III non-small-cell lung cancer

Cost-effectiveness of proton radiotherapy versus photon radiotherapy for non-small cell lung cancer patients: Exploring the model-based approach

INTRODUCTION

Proton radiotherapy (PT) is a promising but more expensive strategy than photon radiotherapy (XRT) for the treatment of non-small cell lung cancer (NSCLC). PT is probably not cost-effective for all patients. Therefore, patients can be selected using normal tissue complication probability (NTCP) models with predefined criteria. This study aimed to explore the cost-effectiveness of three treatment strategies for patients with stage III NSCLC: 1. photon radiotherapy for all patients (XRT_All); 2. PT for all patients (PT_All); 3. PT for selected patients (PT_{Individualized}).

METHODS

A decision-analytical model was constructed to estimate and compare costs and QALYs of all strategies. Three radiation-related toxicities were included: dyspnea, dysphagia and cardiotoxicity. Costs and QALY's were incorporated for grade 2 and ≥ 3 toxicities separately. Incremental Cost-Effectiven Ratios (ICERs) were calculated and compared to a threshold value of €80,000. Additionally, scenario, sensitivity and value of information analyses were performed.

RESULTS

PT_All yielded most QALYs, but was also most expensive. XRT_All was the least effective and least expensive strategy, and the most cost-effective strategy. For thresholds higher than €163,467 per QALY gained, PT_{Individualized} was cost-effective. When assuming equal minutes per fraction (15 minutes) for PT and XRT, PT_{Individualized} was considered the most cost-effective strategy (ICER: €76,299).

CONCLUSION

Currently, PT is not cost-effective for all patients, nor for patient selected on the current NTCP models used in the Dutch indication protocol. However, with improved clinical experience, personnel and treatment costs of PT can decrease over time, which potentially leads to PT_{Individualized}, with optimal patient selection, will becoming a cost-effective strategy.

Development of a prognostic model of overall survival in oropharyngeal cancer from real-world data: PRO.M.E.THE.O

Objective

The PRO.M.E.THE.O. study (PredictiOn Models in Ent cancer for anti-EGFR based THErapy Optimization) aimed to develop a predictive model (PM) of overall survival (OS) for patients with locally advanced oropharyngeal cancer (LAOC) treated with radiotherapy (RT) and cetuximab (Cet) from an Italian dataset.

Methods

We enrolled patients with LAOC from 6 centres treated with RT-Cet. Clinical and treatment variables were collected. Patients were randomly divided into training (TS) (80%) and validation (VS) (20%) sets. A binary logistic regression model was used on the TS with stepwise feature selection and then on VS. Timepoints of 2, 3 and 5 years were considered. The area under the curve (AUC) of receiver operating characteristic of 2, 3 and 5 year and confusion matrix statistics at 5-threshold were used as performance criteria.

Results

Overall, 218 patients were enrolled and 174 (79.8%) were analysed. Age at diagnosis, gender, ECOG performance, clinical stage, dose to high-risk volume, overall treatment time and day of RT interruption were considered in the final PMs. The PMs were developed and represented by nomograms with AUC of 0.75, 0.73 and 0.73 for TS and 0.713, 0.713, 0.775 for VS at 2, 3 and 5 years, respectively.

Conclusions

PRO.M.E.THE.O. allows the creation of a PM for OS in patients with LAOC treated with RT-Cet.

A Comparison of Isotoxic Dose-escalated Radiotherapy in Lung Cancer with Moderate Deep Inspiration Breath Hold, Mid-ventilation and Internal Target Volume Techniques

AIMS

With interest in normal tissue sparing and dose-escalated radiotherapy in the treatment of inoperable locally advanced non-small cell lung cancer, this study investigated the impact of motion-managed moderate deep inspiration breath hold (mDIBH) on normal tissue sparing and dose-escalation potential and compared this to planning with a four-dimensional motion-encompassing internal target volume or motion-compensating mid-ventilation approach.

MATERIALS AND METHODS

Twenty-one patients underwent four-dimensional and mDIBH planning computed tomography scans. Internal and mid-ventilation target volumes were generated on the four-dimensional scan, with mDIBH target volumes generated on the mDIBH scan. Isotoxic target dose-escalation guidelines were used to generate six plans per patient: three with a target dose cap and three without. Target dose-escalation potential, normal tissue complication probability and differences in pre-specified dose-volume metrics were evaluated for the three motion-management techniques.

RESULTS

The mean total lung volume was significantly greater with mDIBH compared with four-dimensional scans. Lung dose (mean and V21 Gy) and mean heart dose were significantly reduced with mDIBH in comparison with four-dimensional-based approaches, and this translated to a significant reduction in heart and lung normal tissue complication probability with mDIBH. In 20/21 patients, the trial target prescription dose cap of 79.2 Gy was achievable with all motion-management techniques.

CONCLUSION

mDIBH aids lung and heart dose sparing in isotoxic dose-escalated radiotherapy compared with four-dimensional planning techniques. Given concerns about lung and cardiac toxicity, particularly in an era of consolidation immunotherapy, reduced normal tissue doses may be advantageous for treatment tolerance and outcome.

Implementation of MR-linac and proton therapy in two radiotherapy departments in The Netherlands: Recommendations based on lessons learned

Recently, two new treatment techniques, i.e. proton therapy and MR-linac based radiotherapy (RT), have been introduced in Dutch RT centres with major impact on daily practice. The content and context of these techniques are frequently described in scientific literature while little is reported about the implementation phase. This process is complex due to a variety of aspects, such as the involvement of multiple stakeholders, significant unpredictability in the start-up phase, the impact of the learning curve, standard operating procedures under development, new catchment areas, and extensive training programs. Insight about implementation in daily care is utterly important for clinics that are about to introduce these new technologies in order to prevent that every centre needs to reinvent the wheel. This position paper gives an overview of the implementation of proton therapy and MR-linac based RT in two large academic RT centres in the Netherlands, i.e. Maastro and Radboudumc respectively. With this paper we aim to report our lessons learned, in order to facilitate other RT centres that consider introducing these and other new techniques in their departments.

Impact of Interobserver Variability in Manual Segmentation of Non-Small Cell Lung Cancer (NSCLC) Applying Low-Rank Radiomic Representation on Computed Tomography

Simple Summary

Discovery of predictive and prognostic radiomic features in cancer is currently of great interest to the radiologic and oncologic community. Tumor phenotypic and prognostic information can be obtained by extracting features on tumor segmentations, and it is typically imaging analysts, physician trainees, and attending physicians who provide these labeled datasets for analysis. The potential impact of level and type of specialty training on interobserver variability in manual segmentation of NSCLC was examined. Although there was some variability in segmentation between readers, the subsequently extracted radiomic features were overall well correlated. High fidelity radiomic feature extraction relies on accurate feature extraction from imaging that produce robust prognostic and predictive radiomic NSCLC biomarkers. This study concludes that this goal can be obtained using segmenters of different levels of training and clinical experience.

Abstract

This study tackles interobserver variability with respect to specialty training in manual segmentation of non-small cell lung cancer (NSCLC). Four readers included for segmentation are: a data scientist (BY), a medical student (LS), a radiology trainee (MH), and a specialty-trained radiologist (SK) for a total of 293 patients from two publicly available databases. Sørensen–Dice (SD) coefficients and low rank Pearson correlation coefficients (CC) of 429 radiomics were calculated to assess interobserver variability. Cox proportional hazard (CPH) models and Kaplan-Meier (KM) curves of overall survival (OS) prediction for each dataset were also generated. SD and CC for segmentations demonstrated high similarities, yielding, SD: 0.79 and CC: 0.92 (BY-SK), SD: 0.81 and CC: 0.83 (LS-SK), and SD: 0.84 and CC: 0.91 (MH-SK) in average for both databases, respectively. OS through the maximal CPH model for the two datasets yielded c-statistics of 0.7 (95% CI) and 0.69 (95% CI), while adding radiomic and clinical variables (sex, stage/morphological status, and histology) together. KM curves also showed significant discrimination between high- and low-risk patients (p-value < 0.005). This supports that readers’ level of training and clinical experience may not significantly influence the ability to extract accurate radiomic features for NSCLC on CT. This potentially allows flexibility in the training required to produce robust prognostic imaging biomarkers for potential clinical translation.

Dose and fractionation schedules in radiotherapy for non-small cell lung cancer

In the field of radiotherapy (RT), the issues of total dose, fractionation, and overall treatment time for non-small cell lung cancer (NSCLC) have been extensively investigated. There is some evidence to suggest that higher treatment intensity of RT, when given alone or sequentially with chemotherapy (CHT), is associated with improved survival. However, there is no evidence that the outcome is improved by RT at a higher dose and/or higher intensity when it is used concurrently with CHT. Moreover, some reports on the combination of full dose CHT with a higher biological dose of RT warn of the significant risk posed by such intensification. Stereotactic body radiotherapy (SBRT) provides a high rate of local control in the management of early-stage NSCLC through the use of high ablative doses. However, in centrally located tumors the use of SBRT may carry a risk of serious damage to the great vessels, bronchi, and esophagus, owing to the high ablative doses needed for optimal tumor control. There is a similar problem with moderate hypofractionation in radical RT for locally advanced NSCLC, and more evidence needs to be gathered regarding the safety of such schedules, especially when used in combination with CHT. In this article, we review the current evidence and questions related to RT dose/fractionation in NSCLC.

Physics of Particle Beam and Hypofractionated Beam Delivery in NSCLC

The dosimetric advantages of particle therapy lead to significantly reduced integral dose to normal tissues, making it an attractive treatment option for body sites such as the thorax. With reduced normal tissue dose comes the potential for dose escalation, toxicity reduction, or hypofractionation. While proton and heavy ion therapy have been used extensively for NSCLC, there are challenges in planning and delivery compared with X-ray-based radiation therapy. Particularly, range uncertainties compounded by breathing motion have to be considered. This article summarizes the current state of particle therapy for NSCLC with a specific focus on the impact of dosimetric uncertainties in planning and delivery.

Impact of CT convolution kernel on robustness of radiomic features for different lung diseases and tissue types

OBJECTIVES

In this study, we aimed to assess the impact of different CT reconstruction kernels on the stability of radiomic features and the transferability between different diseases and tissue types. Three lung diseases were evaluated, i.e. non-small cell lung cancer (NSCLC), malignant pleural mesothelioma (MPM) and interstitial lung disease related to systemic sclerosis (SSc-ILD) as well as four different tissue types, i.e. primary tumor, largest involved lymph node ipsilateral and contralateral lung.

METHODS

Pre-treatment non-contrast enhanced CT scans from 23 NSCLC, 10 MPM and 12 SSc-ILD patients were collected retrospectively. For each patient, CT scans were reconstructed using smooth and sharp kernel in filtered back projection. The regions of interest (ROIs) were contoured on the smooth kernel-based CT and transferred to the sharp kernel-based CT. The voxels were resized to the largest voxel dimension of each cohort. In total, 1386 features were analyzed. Feature stability was assessed using the intraclass correlation coefficient. Features above the stability threshold >0.9 were considered stable.

RESULTS

We observed a strong impact of the reconstruction method on stability of the features (at maximum 26% of the 1386 features were stable). Intensity features were the most stable followed by texture and wavelet features. The wavelet features showed a positive correlation between percentage of stable features and size of the ROI (R2 = 0.79, p = 0.005). Lymph node radiomics showed poorest stability (<10%) and lung radiomics the largest stability (26%). Robustness analysis done on the contralateral lung could to a large extent be transferred to the ipsilateral lung, and the overlap of stable lung features between different lung diseases was more than 50%. However, results of robustness studies cannot be transferred between tissue types, which was investigated in NSCLC and MPM patients; the overlap of stable features for lymph node and lung, as well as for primary tumor and lymph node was very small in both disease types.

CONCLUSION

The robustness of radiomic features is strongly affected by different reconstruction kernels. The effect is largely influenced by the tissue type and less by the disease type.

ADVANCES IN KNOWLEDGE

The study presents to our knowledge the most complete analysis on the impact of convolution kernel on the robustness of CT-based radiomics for four relevant tissue types in three different lung diseases. .

Dyspnea in Patients Receiving Radical Radiotherapy for Non-Small Cell Lung Cancer: A Prospective Study

Background and Purpose

Dyspnea is an important symptomatic endpoint for assessment of radiation-induced lung injury (RILI) following radical radiotherapy in locally advanced disease, which remains the mainstay of treatment at the time of significant advances in therapy including combination treatments with immunotherapy and chemotherapy and the use of local ablative radiotherapy techniques. We investigated the relationship between dose-volume parameters and subjective changes in dyspnea as a measure of RILI and the relationship to spirometry.

Material and Methods

Eighty patients receiving radical radiotherapy for non-small cell lung cancer were prospectively assessed for dyspnea using two patient-completed tools: EORTC QLQ-LC13 dyspnea quality of life assessment and dyspnea visual analogue scale (VAS). Global quality of life, spirometry and radiation pneumonitis grade were also assessed. Comparisons were made with lung dose-volume parameters.

Results

The median survival of the cohort was 26 months. In the evaluable group of 59 patients there were positive correlations between lung dose-volume parameters and a change in dyspnea quality of life scale at 3 months (V₃₀ p=0.017; V₄₀ p=0.026; V₅₀ p=0.049; mean lung dose p=0.05), and a change in dyspnea VAS at 6 months (V₃₀ p=0.05; V₄₀ p=0.026; V₅₀ p=0.028) after radiotherapy. Lung dose-volume parameters predicted a 10% increase in dyspnea quality of life score at 3 months (V₄₀; p=0.041, V₅₀; p=0.037) and dyspnea VAS score at 6 months (V₄₀; p=0.027) post-treatment.

Conclusions

Worsening of dyspnea is an important symptom of RILI. We demonstrate a relationship between lung dose-volume parameters and a 10% worsening of subjective dyspnea scores. Our findings support the use of subjective dyspnea tools in future studies on radiation-induced lung toxicity, particularly at doses below conventional lung radiation tolerance limits.

Study protocol: a multicentre, prospective, phase II trial of isotoxic hypofractionated concurrent chemoradiotherapy for non-small cell lung cancer

INTRODUCTION

Concurrent chemoradiotherapy with conventional fractionation has been acknowledged as one of the standard treatments for locally advanced non-small cell lung cancer (NSCLC). The radiotherapy dose of 60 Gy is far from enough for local tumour control. Due to this fact, hypofractionated radiotherapy can shorten the total treatment duration, partially counteract the accelerated repopulation of tumour cells and deliver a higher biological effective dose, it has been increasingly used for NSCLC. In theory, concurrent hypofractionated chemoradiotherapy can result in an enhanced curative effect. To date, the vast majority of radiotherapy prescriptions assign a uniform radiotherapy dose to all patients. However this kind of uniform radiotherapy prescription may lead to two consequences: excess damage to normal tissues for large tumours and insufficient dose for small tumours. Our study aims to evaluate whether delivering individualised radiotherapy dose is feasible using intensity-modulated radiotherapy.

METHODS AND ANALYSIS

Our study of individualised radiotherapy is a multicenter phase II trial. From April 2019, a total of 30 patients from three Chinese centres, with a proven histological or cytological diagnosis of inoperable NSCLC, will be recruited. The dose of radiation will be increased until one or more of the organs at risk tolerance or the maximum dose of 69 Gy is reached. The primary end point is feasibility, with response rates, progression-free survival and overall survival as secondary end points. The concurrent chemotherapy regimen will be docetaxel plus lobaplatin.

ETHICS AND DISSEMINATION

The study has been approved by medical ethics committees from three research centres. The trial is conducted in accordance with the Declaration of Helsinki.The trial results will be disseminated through academic conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT03606239.

A narrative review of toxicity of chemoradiation and immunotherapy for unresectable, locally advanced non-small cell lung cancer

Despite declining smoking rates, lung cancer remains the second most common malignancy in the United States and the leading cause of cancer-related mortality. Non-small cell lung cancer (NSCLC) comprises roughly 85% of cases, and patients tend to present with advanced disease. Historically, concurrent chemoradiotherapy (CRT) has been the standard of care for stage III unresectable NSCLC but outcomes even with multimodal therapy have remained relatively poor. Efforts to improve outcomes through radiation dose escalation with conventional dose fractionation were unsuccessful with RTOG 0617, demonstrating significantly decreased overall survival (OS) with high dose radiation with respect to standard therapy. The recent PACIFIC trial established a new role for consolidative immune checkpoint blockade therapy after CRT using the programmed death ligand 1 (PD-L1) inhibitor durvalumab, by demonstrating significantly improved progression free survival and OS. Although promising, the addition of immunotherapy to multimodal therapy has generated debate regarding the most effective immune pathways to target, appropriate sequencing of therapy, most effective radiation techniques, and toxicity-related concerns. This review will highlight recent and ongoing trials in unresectable, locally advanced NSCLC that incorporate chemotherapy, radiation, and immunotherapy with an emphasis on analysis of treatment-related toxicities and implications for future study design.

Radiation dose escalation with modified fractionation schedules for locally advanced NSCLC: A systematic review

Concomitant chemo‐radiotherapy (cCRT) with 60 Gy in 30 fractions is the standard of care for stage 111 non‐small cell lung cancer (NSCLC). With a median overall survival of 28.7 months at best and maximum locoregional control rates of 70% at two years, the prognosis for these patients is still dismal. This systematic review summarizes data on dose escalation by alternative fractionation, which has been explored as a primary strategy to improve both local control and overall survival over the past three decades. A Pubmed literature search was performed according to the PRISMA guidelines. Because of the large variety of radiation regimens total doses were converted to EQD_2,T. Only studies using an EQD_2,T of at least 49.5 Gy, which corresponds to the conventional 60 Gy in six weeks, were included. In a total of 3256 patients, the median OS was 17 months (range 7.4–30 months). While OS was better for patients treated after the year 2000 (P = 0.003) or with a mandatory ¹⁸F‐FDG‐PET‐CT in the diagnostic work‐up (P = 0.001), treatment sequence did not make a difference (P = 0.106). The most commonly reported toxicity was acute esophagitis (AE) with a median rate of 24% (range 0%–84%). AE increased at a rate of 0.5% per Gy increment in EQD_2,T (P = 0.016). Dose escalation above the conventional 60 Gy using modified radiation fractionation schedules and shortened OTT yield similar mOS and LRC regardless of treatment sequence with a significant EQD_2,T dependent increase in AE.

Key points

Significant findings

Modified radiation dose escalation sequentially combined with chemotherapy yields similar outcome as concomitant treatment.

OS is better with the mandatory inclusion of FDG‐PET‐CT in the diagnostic work‐up.

The risk of acute esophagitis increases with higher EQD_2,T.

What this study adds

Chemo‐radiotherapy (CRT) with modified dose escalation regimens yields OS and LC rates in the range of standard therapy regardless of treatment sequence. This broadens the database of curative options in patients who are not eligible concomitant CRT.

Handgrip weakness, low fat-free mass, and overall survival in non-small cell lung cancer treated with curative-intent radiotherapy

BACKGROUND

Assessment of handgrip strength and fat-free mass provides quick and objective information on muscle performance and mass that might complement subjective World Health Organization Performance Status (WHO PS). We investigated to what extent the presence of pre-treatment handgrip weakness and low fat-free mass index (FFMI) provides additional prognostic information on top of well-established prognostic factors (including WHO PS) in non-small cell lung cancer (NSCLC) patients selected for curative-intent (chemo)radiation.

METHODS

Prospectively, patients with early and locally advanced NSCLC (stages I-III) treated with (chemo)radiation were enrolled. Handgrip weakness and low FFMI, derived from bioelectrical impedance analysis, were defined using normative values and were correlated with overall survival (OS).

RESULTS

We included 936 patients (age 68 ± 10 years; 64% male; 19% stage I, 9% stage II, and 72% stage III disease; 26% handgrip weakness; 27% low FFMI). In patients with good performance status (WHO PS 0 or 1), handgrip weakness and low FFMI were significant prognostic factors for OS, after adjustment for age, gender, disease stage, and co-morbidities. The combined presence of handgrip weakness and low FFMI was a strong prognostic factor for OS when compared with patients with normal handgrip strength and FFMI (hazard ratio: 1.79, 95% confidence interval: 1.34-2.40, P < 0.0001). In patients with impaired performance status (WHO PS ≥ 2, 19% of sample), handgrip weakness and low FFMI were not related to OS.

CONCLUSIONS

In early and locally advanced NSCLC patients treated with curative-intent (chemo)radiation who have good WHO PS, patients with combined handgrip weakness and low FFMI have the worst prognosis.

High dose radiation therapy based on normal tissue constraints with concurrent chemotherapy achieves promising survival of patients with unresectable stage III non-small cell lung cancer

BACKGROUND AND PURPOSE

We aimed to investigate the potential of individual isotoxic dose escalation based on normal tissue constraints (NTC), hypothesizing that high dose radiation therapy would be superior to standard-dose in concurrent chemoradiotherapy for unresectable stage III non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Individually prescribed radiation doses were calculated based on NTC. Patients with total tumour radiation doses ≥66 Gy were assigned to the high dose (HD, ≥66 Gy) group, and all other patients were assigned to the standard-dose (SD, <66 Gy) group. Each patient was retrospectively assigned an Eighth edition of American Joint Committee on Cancer disease stage based on the imaging data of initial diagnosis to avoid over- and under-staging. Intensity modulated radiation therapy plans were optimized to minimize the volumes of organs at risk exposed to radiation. The primary endpoint was overall survival.

RESULTS

From March 2006 to September 2012, 140 patients were enrolled and assigned to two groups: 71 patients into the HD group and 69 patients into the SD group. The median survival time (MST) was significantly higher in the HD group (33.5 months) than in the SD group (21 months), (p < 0.0001). Overall 5-year survival rates were significantly higher in the HD group than in the SD group (37.8% vs 16.7%). Median progression-free survival was 19 months in the HD group and 11 months in the SD group (p < 0.0001). No difference in severe (grade 3-5) toxic effects was noted between the two groups.

CONCLUSIONS

The significant positive association observed between prescribed dose and survival suggests that individualized isotoxic dose-escalated radiation based on NTC might improve survival in this cohort of stage III NSCLC Chinese patients.

Photons or protons for reirradiation in (non-)small cell lung cancer: Results of the multicentric ROCOCO in silico study

OBJECTIVE

Locally recurrent disease is of increasing concern in (non-)small cell lung cancer [(N)SCLC] patients. Local reirradiation with photons or particles may be of benefit to these patients. In this multicentre in silico trial performed within the Radiation Oncology Collaborative Comparison (ROCOCO) consortium, the doses to the target volumes and organs at risk (OARs) were compared when using several photon and proton techniques in patients with recurrent localised lung cancer scheduled to undergo reirradiation.

METHODS

24 consecutive patients with a second primary (N)SCLC or recurrent disease after curative-intent, standard fractionated radio(chemo)therapy were included in this study. The target volumes and OARs were centrally contoured and distributed to the participating ROCOCO sites. Remaining doses to the OARs were calculated on an individual patient's basis. Treatment planning was performed by the participating site using the clinical treatment planning system and associated beam characteristics.

RESULTS

Treatment plans for all modalities (five photon and two proton plans per patient) were available for 22 patients (N = 154 plans). 3D-conformal photon therapy and double-scattered proton therapy delivered significantly lower doses to the target volumes. The highly conformal techniques, i.e., intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), CyberKnife, TomoTherapy and intensity-modulated proton therapy (IMPT), reached the highest doses in the target volumes. Of these, IMPT was able to statistically significantly decrease the radiation doses to the OARs.

CONCLUSION

Highly conformal photon and proton beam techniques enable high-dose reirradiation of the target volume. They, however, significantly differ in the dose deposited in the OARs. The therapeutic options, i.e., reirradiation or systemic therapy, need to be carefully weighed and discussed with the patients.

ADVANCES IN KNOWLEDGE

Highly conformal photon and proton beam techniques enable high-dose reirradiation of the target volume. In light of the abilities of the various highly conformal techniques to spare specific OARs, the therapeutic options need to be carefully weighed and patients included in the decision-making process.

The evolving role of radiotherapy in non-small cell lung cancer

Lung cancer is the most commonly diagnosed cancer and biggest cause of cancer mortality worldwide with non-small cell lung cancer (NSCLC) accounting for most cases. Radiotherapy (RT) plays a key role in its management and is used at least once in over half of patients in both curative and palliative treatments. This narrative review will demonstrate how the evolution of RT for NSCLC has been underpinned by improvements in RT technology. These improvements have facilitated geometric individualization, increasingly accurate treatment and now offer the ability to deliver truly individualized RT. In this review, we summarize and discuss recent developments in the field of advanced RT in early stage, locally advanced and metastatic NSCLC. We highlight limitations in current approaches and discuss future potential treatment strategies for patients with NSCLC.

Multifactorial risk factors for mortality after chemotherapy and radiotherapy for non-small cell lung cancer

BACKGROUND AND PURPOSE

A higher radiation dose to the heart is known to be associated with increased mortality in non-small cell lung cancer (NSCLC) patients. It is however unknown what the contribution of the heart dose is when other risk factors for mortality are also accounted for.

MATERIALS AND METHODS

We constructed and externally validated prediction models of mortality after definitive chemoradiotherapy for NSCLC. Models were developed in 145 stage I-IIIB NSCLC patients. Clinical (performance status, age, gross tumour volume (GTV) combining primary tumour and involved lymph nodes, current smoker) and dosimetric (mean lung (MLD) and heart (MHD) dose) variables were considered. Multivariable logistic regression models predicting 12 and 24 month mortality were built in 5-fold cross-validation. Discrimination and calibration was assessed in 3 external validation datasets containing 878 (via distributed learning), 127 and 96 NSCLC patients.

RESULTS

The best discriminating prediction models combined GTV, smoker and/or MHD: bootstrapping AUC (95% CI) of 0.74 (0.66-0.78) and 0.69 (0.55-0.74) at 12 and 24 months. At external validation, the 24 month mortality GTV-smoker-MHD model robustly showed moderate discrimination (AUC = 0.61-0.64 before and 0.64-0.65 after model update) with limited 0.01-0.07 improvement over a GTV-only model, and calibration slope (0.64-0.65). This model can identify patients for whom a MHD reduction may be useful (e.g. PPV = 77%, NPV = 52% (60% cut-off)).

CONCLUSIONS

Tumour volume is strongly related to mortality risk in the first 2 years after chemoradiotherapy for NSCLC. Modelling indicates that efforts to reduce cardiac dose may be relevant for small tumours and that smoking has an important negative association with survival.

Pulmonary function changes following helical tomotherapy in patients with inoperable, locally advanced non-small cell lung cancer

PURPOSE

To evaluate alterations in pulmonary function indices after helical tomotherapy and explore potential associations with biologically corrected dosimetric parameters.

PATIENTS AND METHODS

In 64 patients with inoperable locally advanced non-small cell lung cancer, pulmonary function tests before and within 6 months after radiotherapy were evaluated retrospectively. In the case of concurrent chemotherapy a total dose of 67.2 Gy was delivered, otherwise 70.5 Gy was provided. In 44 patients, late pulmonary function changes (≥6 months after radiotherapy) could also be assessed.

RESULTS

In the entire patient group, there were significant declines in forced expiratory volume in 1s (FEV₁) (average change -4.1% predicted; P = 0.007), in forced vital capacity (FVC) (-4.9% predicted; P = 0.002), total lung capacity (TLC) (-5.8% predicted; P = 0.0016) and DL_CO (diffusing capacity of the lung for carbon monoxide corrected for hemoglobin level) (-8.6% predicted; P < 0.001) during the first 6 months. Corresponding FEV₁, FVC, TLC and DL_CO declines in the subgroup with late measurements (after 11.3 months on average) were -5.7, -7.4, -7.0, -9.8% predicted. A multivariate analysis including V_5 Gy, V_10 Gy, V_20 Gy, V_40 Gy, V_60 Gy, mean lung dose (MLD), gross tumor volume (GTV) and planning target volume (PTV) as potential covariates showed that GTV was the most consistent contributor, being significant for ∆FEV₁ (P = 0.003), ∆FVC (P = 0.003), ∆TLC (P = 0.001) and ∆DL_CO (P = 0.01). V_5 Gy or V_10 Gy did not contribute to any of the lung function changes.

CONCLUSIONS

The decline in pulmonary function indices after helical tomotherapy was of similar magnitude to that observed in studies reporting the effect of conformal radiotherapy on lung function. Diffusion capacity was the parameter showing the largest decrease following radiation therapy as compared to baseline and correlated with gross tumor volume. None of the alterations in pulmonary function tests were associated with the lung volume receiving low-dose radiation.

Assessment of contour variability in target volumes and organs at risk in lung cancer radiotherapy

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It aimed to examine if there’s any significant differences in TV & OAR contouring in lung trials QA.

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Statistically significant difference in trial protocol compliances of TV & OAR contouring existed.

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Trial protocol compliances of TV & OARs delineation can be identified through trial QA.

Aims

This study aimed to examine whether any significant differences existed in trial protocol compliance in target volumes (TV) and organs at risk (OARs) contouring amongst clinical oncologists specialised in lung cancer radiotherapy.

Materials/methods

Two lung radiotherapy trials that require all prospective investigators to submit pre-trial outlining quality assurance (QA) benchmark cases were selected. The contours from the benchmark cases were compared against a set of reference contours which were defined by the trial management group (TMG). In order to quantify the degree of variation in TV and OARs contouring, the matching index (MI), Dice coefficient (DICE), Jaccard index (JI), Van‘t Riet Index and geographical miss index (GMI) were calculated.

Results

A total of 198 structures contoured by 21 clinicians were collected from the outlining benchmark cases. There were 40 clinical target volumes (CTV), 32 spinal cord, 36 oesophagus, 36 heart and 54 lungs volumes included in the study. Analysis of the pre-trial benchmark cases revealed statistically significant differences (p ≤ 0.05) in trial protocol compliances between clinical oncologists’ target volume and organs at risk contours. Our results demonstrated that the lung contours had the highest level of conformity, followed by heart, CTV, spinal cord and oesophagus respectively.

Conclusions

This study showed that there was a statistically significant difference in trial protocol compliance for lung clinical oncologists’ TV and OARs contouring within the pre-trial QA benchmark cases. Trial protocol compliances of TV and OARs delineation can be identified through assessing outlining QA benchmark cases.

Development and internal validation of a multinomial NTCP model for the severity of acute dyspnea after radiotherapy for lung cancer

BACKGROUND AND PURPOSE

Dyspnea evolution after radiotherapy for lung cancer is complex with potential symptom deterioration and improvement from baseline. We developed and internally validated a multinomial normal tissue complication probability (NTCP) model predicting dyspnea grade.

MATERIALS AND METHODS

Patient-reported dyspnea was collected pre-treatment and during 6 months follow-up for 182 stage I-IV lung cancer patients treated with radical (chemo)radiotherapy. Dyspnea changes (ΔDys) from the baseline grade (Dys₀) to the follow-up grade (Dys) were evaluated. A multinomial logistic regression model simultaneously predicting 3 grades of Dys (Dys ≥ 3, Dys = 2 and Dys ≤ 1 (reference level)) was optimized. Reference NTCP models predicting Dys ≥ 2 and Dys ≥ 3 risks irrespective of Dys₀ were generated for comparison. Models were shrunken and performance was assessed using optimism-corrected AUC (bootstrapping).

RESULTS

Rates of ΔDys ≥ 1 (deterioration) and ΔDys ≤ -1 (improvement) at 6 months were 31.9% and 12.6%. Dys ≥ 3, Dys = 2 and Dys ≤ 1 rates were 13.7%, 20.9% and 65.4%, respectively. The multinomial model (combining the risk factors Dys₀ and MLD and the protective factor chemotherapy treatment) predicted Dys ≥ 3, Dys = 2 and Dys ≤ 1 with AUC (95% CI) of 0.72 (0.65-0.75) 0.76 (0.72-0.79) and 0.78 (0.74-0.80), respectively. Reference Dys ≥ 2 and Dys ≥ 3 models showed worse AUC: 0.64 (0.59-0.67) and 0.66 (0.50-0.70), respectively.

CONCLUSIONS

Dyspnea grade could be predicted with high accuracy using a multinomial NTCP model, yielding personalized dyspnea symptom improvement and deterioration risks.

Individualized accelerated isotoxic concurrent chemo-radiotherapy for stage III non-small cell lung cancer: 5-Year results of a prospective study

BACKGROUND

Stage III non-small cell lung cancer (NSCLC) still has a poor prognosis. Prior studies with individualized, accelerated, isotoxic dose escalation (INDAR) with 3D-CRT showed promising results, especially in patients not treated with concurrent chemo-radiotherapy. We investigated if INDAR delivered with IMRT would improve the overall survival (OS) of stage III NSCLC patients treated with concurrent chemotherapy and radiotherapy.

PATIENTS AND METHODS

Patients eligible for concurrent chemo-radiotherapy were entered in this prospective study. Radiotherapy was given to a dose of 45 Gy/30 fractions BID (1.5 Gy/fraction), followed by QD fractions of 2 Gy until a total dose determined by the normal tissue constraints. The primary endpoint was OS, secondary endpoints were loco-regional relapses and toxicity.

RESULTS

From May 4, 2009 until April 26, 2012, 185 patients were included. The mean tumor dose was 66.0 ± 12.8 Gy (36-73 Gy), delivered in a mean of 39.7 fractions in an overall treatment time of 38.2 days. The mean lung dose (MLD) was 17.3 Gy. The median OS was 19.8 months (95% CI 17.3-22.3) with a 5-year OS of 24.3%. Loco-regional failures as first site of recurrence occurred in 59/185 patients (31.8%). Isolated nodal failures (INF) were observed in 3/185 patients (1.6%). Dyspnea grade 3 was seen in 3.2% of patients and transient dysphagia grade 3 in 22%.

CONCLUSIONS

INDAR with IMRT concurrently with chemotherapy did not lead to a sign of an improved OS in unselected stage III NSCLC patients.

Radiotherapy boost in patients with hypoxic lesions identified by 18F-FMISO PET/CT in non-small-cell lung carcinoma: can we expect a better survival outcome without toxicity? [RTEP5 long-term follow-up]

PURPOSE

Chemoradiotherapy is the reference curative-intent treatment for nonresectable locally advanced non-small-cell lung carcinoma (NSCLC), with unsatisfactory survival, partially due to radiation resistance in hypoxic tissues. The objective was to update survival and toxicity at 3 years following radiotherapy boost to hypoxic tumours in NSCLC patients treated with curative-intent chemoradiotherapy.

METHODS

This was an open-label, nonrandomized, multicentre, phase II clinical trial. ¹⁸F-Fluoromisonidazole (¹⁸F-FMISO) PET/CT was used to determine the hypoxic profile of the patients. ¹⁸F-FMISO-positive patients and those without organ-at-risk constraints received a radiotherapy boost (70-84 Gy); the others received standard radiotherapy (66 Gy). Overall survival (OS), progression-free survival (PFS) and safety were assessed.

RESULTS

A total of 54 patients were evaluated. OS and PFS rates at 3 years were 48.5% and 28.8%, respectively. The median OS in the ¹⁸F-FMISO-positive patients was 25.8 months and was not reached in the ¹⁸F-FMISO-negative patients (p = 0.01). A difference between the groups was also observed for PFS (12 months vs. 26.2 months, p = 0.048). In ¹⁸F-FMISO-positive patients, no difference was observed in OS in relation to dose, probably because of the small sample size (p = 0.30). However, the median OS seemed to be in favour of patients who received the radiotherapy boost (26.5 vs. 15.3 months, p = 0.71). In patients who received the radiotherapy boost, no significant late toxicities were observed.

CONCLUSION

¹⁸F-FMISO uptake in NSCLC patients is strongly associated with features indicating a poor prognosis. In ¹⁸F-FMISO-positive patients, the radiotherapy boost seemed to improve the OS by 11.2 months. A further clinical trial is needed to investigate the efficacy of a radiotherapy boost in patients with hypoxic tumours.

Accelerated, Dose escalated, Sequential Chemoradiotherapy in Non-small-cell lung cancer (ADSCaN): a protocol for a randomised phase II study

INTRODUCTION

Lung cancer is the most common cause of cancer mortality in the UK, and non-small-cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancers. Most patients present with inoperable disease; therefore, radiotherapy plays a major role in treatment. However, the majority of patients are not suitable for the gold standard treatment (concurrent chemoradiotherapy) due to performance status and comorbidities. Novel strategies integrating radiotherapy advances and radiobiological knowledge need to be evaluated in patients treated with sequential chemoradiotherapy. Four separate dose escalation accelerated radiotherapy schedules have been completed in UK (CHART-ED, IDEAL-CRT, I-START and Isotoxic IMRT). This study will compare these schedules with a UK standard sequential chemoradiotherapy schedule of 55 Gy in 20 fractions over 4 weeks. As it would be impossible to test all schedules in a phase III study, the aim is to use a combined randomised phase II screening/'pick the winner' approach to identify the best schedule to take into a randomised phase III study against conventionally fractionated radiotherapy.

METHODS AND ANALYSIS

Suitable patients will have histologically/cytologically confirmed, stage III NSCLC and are able to undergo chemoradiotherapy treatment. The study will recruit 360 patients; 120 on the standard arm and 60 on each experimental arm. Patients will complete 2-4 cycles of platinum-based chemotherapy before being randomised to one of the radiotherapy schedules. The primary endpoint is progression-free survival, with overall survival, time to local-regional failure, toxicity and cost-effectiveness as secondary objectives.

ETHICS AND DISSEMINATION

The study has received ethical approval (research ethics committee (REC) reference: 16/WS/0165) from the West of Scotland REC 1. The trial is conducted in accordance with the Declaration of Helsinki and Good Clinical Practice. Trial results will be published in a peer-reviewed journal and presented internationally.

TRIAL REGISTRATION NUMBER

ISRCTN47674500.

Survival in early lung cancer patients treated with high dose radiotherapy is independent of pathological confirmation

BACKGROUND

Approximately 15% of lung cancer patients are diagnosed in early stages. Microscopic proof of disease cannot always be obtained because of comorbidity or reluctance to undergo invasive diagnostic procedures. In the current study, survival data of patients with and without pathology are compared.

METHODS

One hundred and sixty three patients with NSCLC I-IIb (T3 N0) treated between 2002 and 2016 were eligible: 123 (75%) had pathological confirmation of disease, whereas 40 (25%) did not. In accordance with international guidelines, both groups received radiotherapy. Comorbidity was assessed with the Charlson Comorbidity Index (CCI).

RESULTS

The median follow-up was 28.6 months (range: 0.3-162): 66 (40%) patients are still alive, while 97 (59%) patients died: 48 (29%) cancer-related deaths and 49 (30%) from causes other than cancer. Median overall survival (OS) in patients without pathological confirmation was 58.6 months (range: 0.5-162), which did not differ from those with microscopic proof of disease (39.4 months, range: 0.3-147.5; logrank P = 0.481). Median cancer-specific survival (CSS) also did not differ at 113.4 months (range: 0.5-162) in the non-confirmation group (logrank P = 0.763) versus 51.5 months (range: 3.7-129.5) in patients with pathology. In Cox regression, a CCI of ≥ 3 was associated with poor OS (hazard ratio 2.0; range 1.2-3.4; P = 0.010) and CSS (hazard ratio 2.0; 1.0-4.0; P = 0.043).

CONCLUSION

OS and CSS in early lung cancer patients depend on comorbidity rather than on pathological confirmation of disease.

Dose escalation to 84 Gy with concurrent chemotherapy in stage III NSCLC appears excessively toxic: Results from a prematurely terminated randomized phase II trial

OBJECTIVES

Concurrent chemoradiotherapy is the mainstay treatment for NSCLC stage III disease. To investigate whether radiation dose escalation based on individual normal tissue constraints can improve outcome, the Swedish lung cancer study group launched this randomized phase II trial.

MATERIALS AND METHODS

NSCLC patients with stage III disease, good performance status (0-1) and adequate lung function (FEV1 > 1.0 L and CO diffusion capacity > 40%) received three cycles of cisplatin (75 mg/m² day 1) and vinorelbine (25 mg/m² day 1 and 8) every third week. Radiotherapy started concurrently with the second cycle, with either 2 Gy daily, 5 days a week, to 68 Gy (A) or escalated therapy (B) based on constraints to the spinal cord, esophagus and lungs up to 84 Gy by adding an extra fraction of 2 Gy per week.

RESULTS

A pre-planned safety analysis revealed excessive toxicity and decreased survival in the escalated arm, and the study was stopped. Thirty-six patients were included during 2011-2013 (56% male, 78% with adenocarcinoma, 64% with PS 0 and 53% with stage IIIB). The median progression-free survival (PFS) and overall survival (OS) were 11 and 17 months in arm B compared to the encouraging results of 28 and 45 months in the standard arm. The 1- and 3-year survival rates were 56% and 33% (B) and 72% and 56% (A), respectively. There were seven toxicity-related deaths due to esophageal perforations and pneumonitis: five in the escalated group and two with standard treatment.

CONCLUSION

Dose-escalated concurrent chemoradiotherapy to 84 Gy to primary tumor and nodal disease is hazardous, with a high risk of excessive toxicity, whereas modern standard dose chemoradiotherapy with proper staging given in the control arm shows a promising outcome with a median survival of 45 months and a 3-year survival of 56% (NCT01664663).

An overview on personalisation of radiotherapy prescriptions in locally advanced non-small cell lung cancer: Are we there yet?

Standard of care radiotherapy in LA-NSCLC is 60-66 Gy in 30-33 fractions. However outcomes for these patients are poor with 5-year survival in the range of 10-20%. Randomised controlled trials have shown that dose escalation in a linear fashion does not improve outcomes for all patients, thus there is a need to tailor the prescription to the individual patient. This review assesses the strategies published to personalise the radiation therapy dose prescription in LA-NSCLC. A systematic and scoping search of the literature was performed to identify studies that met the inclusion criteria. 19 relevant studies were identified ranging from prospective clinical trials to mathematically modelled concept studies. Heterogeneity existed between all clinical studies. Nine heterogeneous publications proposed methodology to adapt the dose prescription to the individual patient. A number of encouraging strategies have been identified but fall short of the evidence level required to influence clinical practice.

Is heterogeneity in stage 3 non-small cell lung cancer obscuring the potential benefits of dose-escalated concurrent chemo-radiotherapy in clinical trials?

The current standard of care for the management of inoperable stage 3 non-small cell lung cancer (NSCLC) is concurrent chemoradiotherapy (cCRT) using radiotherapy dose-fractionation and chemotherapy regimens that were established 3 decades ago. In an attempt to improve the chances of long-term control from cCRT, dose-escalation of the radiotherapy dose was assessed in the RTOG 0617 randomised control study comparing the standard 60 Gy in 30 fractions with a high-dose arm receiving 74 Gy in 37 fractions. Following the publication of this trial the thoracic oncology community were surprised to learn that there was worse survival in the dose-escalated arm and that for now the standard of care must remain with the lower dose. In this article we review the RTOG 0617 paper with subsequent analyses and studies to explore why the use of dose-escalated cCRT in stage 3 NSCLC has not shown the benefits that were expected. The overarching theme of this opinion piece is how heterogeneity between stage 3 NSCLC cases in terms of patient, tumour, and clinical factors may obscure the potential benefits of dose-escalation by causing imbalances in the arms of studies such as RTOG 0617. We also examine recent advances in the staging, management, and technological delivery of radiotherapy in NSCLC and how these may be employed to optimise cCRT trials in the future and ensure that any potential benefits of dose-escalation can be detected.

Improved effectiveness of stereotactic radiosurgery in large brain metastases by individualized isotoxic dose prescription: an in silico study

INTRODUCTION

In large brain metastases (BM) with a diameter of more than 2 cm there is an increased risk of radionecrosis (RN) with standard stereotactic radiosurgery (SRS) dose prescription, while the normal tissue constraint is exceeded. The tumor control probability (TCP) with a single dose of 15 Gy is only 42%. This in silico study tests the hypothesis that isotoxic dose prescription (IDP) can increase the therapeutic ratio (TCP/Risk of RN) of SRS in large BM.

MATERIALS AND METHODS

A treatment-planning study with 8 perfectly spherical and 46 clinically realistic gross tumor volumes (GTV) was conducted. The effects of GTV size (0.5-4 cm diameter), set-up margins (0, 1, and 2 mm), and beam arrangements (coplanar vs non-coplanar) on the predicted TCP using IDP were assessed. For single-, three-, and five-fraction IDP dose-volume constraints of V_12Gy = 10 cm³, V_19.2 Gy = 10 cm³, and a V_20Gy = 20 cm³, respectively, were used to maintain a low risk of radionecrosis.

RESULTS

In BM of 4 cm in diameter, the maximum achievable single-fraction IDP dose was 14 Gy compared to 15 Gy for standard SRS dose prescription, with respective TCPs of 32 and 42%. Fractionated SRS with IDP was needed to improve the TCP. For three- and five-fraction IDP, a maximum predicted TCP of 55 and 68% was achieved respectively (non-coplanar beams and a 1 mm GTV-PTV margin).

CONCLUSIONS

Using three-fraction or five-fraction IDP the predicted TCP can be increased safely to 55 and 68%, respectively, in large BM with a diameter of 4 cm with a low risk of RN. Using IDP, the therapeutic ratio of SRS in large BM can be increased compared to current SRS dose prescription.

Incorporating spatial dose metrics in machine learning-based normal tissue complication probability (NTCP) models of severe acute dysphagia resulting from head and neck radiotherapy

Severe acute dysphagia commonly results from head and neck radiotherapy (RT). A model enabling prediction of severity of acute dysphagia for individual patients could guide clinical decision-making. Statistical associations between RT dose distributions and dysphagia could inform RT planning protocols aiming to reduce the incidence of severe dysphagia. We aimed to establish such a model and associations incorporating spatial dose metrics. Models of severe acute dysphagia were developed using pharyngeal mucosa (PM) RT dose (dose-volume and spatial dose metrics) and clinical data. Penalized logistic regression (PLR), support vector classification and random forest classification (RFC) models were generated and internally (173 patients) and externally (90 patients) validated. These were compared using area under the receiver operating characteristic curve (AUC) to assess performance. Associations between treatment features and dysphagia were explored using RFC models. The PLR model using dose-volume metrics (PLRstandard) performed as well as the more complex models and had very good discrimination (AUC = 0.82) on external validation. The features with the highest RFC importance values were the volume, length and circumference of PM receiving 1 Gy/fraction and higher. The volumes of PM receiving 1 Gy/fraction or higher should be minimized to reduce the incidence of severe acute dysphagia.

Blood-based biomarkers for precision medicine in lung cancer: precision radiation therapy

Both tumors and patients are complex and models that determine survival and toxicity of radiotherapy or any other treatment ideally must take into account this variability as well as its dynamic state. The genetic features of the tumor and the host, and increasingly also the epi-genetic and proteomic characteristics, are being unraveled. Multiple techniques, including histological examination, blood sampling, measurement of circulating tumor cells (CTCs), and functional and molecular imaging, can be used for this purpose. However, the effects of radiation on the tumor and on organs at risk (OARs) are also influenced by the applied dose and volume of irradiated tissues. Combining all these biological, clinical, imaging, and dosimetric parameters in a validated prognostic or predictive model poses a major challenge. Here we aimed to provide an objective review of the potential of blood markers to guide high precision radiation therapy. A combined biological-mathematical approach opens new doors beyond prognostication of patients, as it allows truly precise oncological treatment. Indeed, the core for individualized and precision medicine is not only selection of patients, but even more the optimization of the therapeutic window on an individual basis. A holistic model will allow for determination of an individual dose-response relationship for each organ at risk for each tumor in each individual patient for the complete oncological treatment package. This includes, but is not limited to, radiotherapy alone. Individualized dose-response curves will allow for consideration of different doses of radiation and combinations with other drugs to plan for both optimal toxicity and complete response. Insights into the interactions between a multitude of parameters will lead to the discovery of new pathways and networks that will fuel new biological research on target discovery.

Normal lung sparing Tomotherapy technique in stage III lung cancer

PURPOSE

Radiation pneumonitis (RP) has been a challenging obstacle in treating stage III lung cancer patients. Beam angle optimization (BAO) technique for Tomotherapy was developed to reduce the normal lung dose for stage III non-small cell lung cancer (NSCLC). Comparative analyses on plan quality by 3 different Intensity-modulated radiation therapy (IMRT) methods with BAO were done.

MATERIALS AND METHODS

Ten consecutive stage IIIB NSCLC patients receiving linac-based static IMRT (L-IMRT) with total 66 Gy in 33 fractions to the PTV were selected. Two additional Tomotherapy-based IMRT plans (helical beam (TH-IMRT) and static beam (TD-IMRT)) were generated on each patient. To reduce the normal lung dose, Beam angles were optimized by using complete and directional block functions in Tomotherapy based on knowledge based statistical analysis. Plan quality was compared with target coverage, normal organ sparing capability, and normal tissue complication probability (NTCP). Actual beam delivery times and risk of RP related with planning target volume (PTV) were also evaluated.

RESULTS

The best PTV coverage measured by conformity index and homogeneity index was achievable by TH-IMRT (0.82 and 1.06), followed by TD-IMRT (0.81 and 1.07) and L-IMRT (0.75 and 1.08). Mean lung dose was the lowest in TH-IMRT plan followed by TD-IMRT and L-IMRT, all of which were ≤20 Gy. TH-IMRT plan could significantly lower the lung volumes receiving low to medium dose levels: V5~30 when compared to L-IMRT plan; and V5~20 when compared to TD-IMRT plan, respectively. TD-IMRT plan was significantly better than L-IMRT with respects to V20 and V30 and there was no significant difference with respect to V40 among three plans. The NTCP of the lung was the lowest in TH-IMRT plan, followed by TD-IMRT and L-IMRT (6.42% vs. 6.53% vs. 8.11%). Beam delivery time was the shortest in TD-IMRT plan followed by L-IMRT. As PTV length increased, NTCP and Mean lung dose proportionally increased significantly in all three plans.

CONCLUSION

Advantageous profiles by TH-IMRT could be achieved by BAO by complete and directional block functions. Current observation could help radiation oncologists to make wise selection of IMRT method for stage IIIB NSCLC.

Treating locally advanced lung cancer with a 1.5T MR-Linac - Effects of the magnetic field and irradiation geometry on conventionally fractionated and isotoxic dose-escalated radiotherapy

PURPOSE

This study investigates the feasibility and potential benefits of radiotherapy with a 1.5T MR-Linac for locally advanced non-small cell lung cancer (LA NSCLC) patients.

MATERIAL AND METHODS

Ten patients with LA NSCLC were retrospectively re-planned six times: three treatment plans were created according to a protocol for conventionally fractionated radiotherapy and three treatment plans following guidelines for isotoxic target dose escalation. In each case, two plans were designed for the MR-Linac, either with standard (∼7mm) or reduced (∼3mm) planning target volume (PTV) margins, while one conventional linac plan was created with standard margins. Treatment plan quality was evaluated using dose-volume metrics or by quantifying dose escalation potential.

RESULTS

All generated treatment plans fulfilled their respective planning constraints. For conventionally fractionated treatments, MR-Linac plans with standard margins had slightly increased skin dose when compared to conventional linac plans. Using reduced margins alleviated this issue and decreased exposure of several other organs-at-risk (OAR). Reduced margins also enabled increased isotoxic target dose escalation.

CONCLUSION

It is feasible to generate treatment plans for LA NSCLC patients on a 1.5T MR-Linac. Margin reduction, facilitated by an envisioned MRI-guided workflow, enables increased OAR sparing and isotoxic target dose escalation for the respective treatment approaches.

Developing and Validating a Survival Prediction Model for NSCLC Patients Through Distributed Learning Across 3 Countries

PURPOSE

Tools for survival prediction for non-small cell lung cancer (NSCLC) patients treated with chemoradiation or radiation therapy are of limited quality. In this work, we developed a predictive model of survival at 2 years. The model is based on a large volume of historical patient data and serves as a proof of concept to demonstrate the distributed learning approach.

METHODS AND MATERIALS

Clinical data from 698 lung cancer patients, treated with curative intent with chemoradiation or radiation therapy alone, were collected and stored at 2 different cancer institutes (559 patients at Maastro clinic (Netherlands) and 139 at Michigan university [United States]). The model was further validated on 196 patients originating from The Christie (United Kingdon). A Bayesian network model was adapted for distributed learning (the animation can be viewed at https://www.youtube.com/watch?v=ZDJFOxpwqEA). Two-year posttreatment survival was chosen as the endpoint. The Maastro clinic cohort data are publicly available at https://www.cancerdata.org/publication/developing-and-validating-survival-prediction-model-nsclc-patients-through-distributed, and the developed models can be found at www.predictcancer.org.

RESULTS

Variables included in the final model were T and N category, age, performance status, and total tumor dose. The model has an area under the curve (AUC) of 0.66 on the external validation set and an AUC of 0.62 on a 5-fold cross validation. A model based on the T and N category performed with an AUC of 0.47 on the validation set, significantly worse than our model (P<.001). Learning the model in a centralized or distributed fashion yields a minor difference on the probabilities of the conditional probability tables (0.6%); the discriminative performance of the models on the validation set is similar (P=.26).

CONCLUSIONS

Distributed learning from federated databases allows learning of predictive models on data originating from multiple institutions while avoiding many of the data-sharing barriers. We believe that distributed learning is the future of sharing data in health care.

The Impact of Cardiac Radiation Dosimetry on Survival After Radiation Therapy for Non-Small Cell Lung Cancer

PURPOSE

The heart receives high radiation doses during radiation therapy of advanced-stage lung cancer. We have explored associations between overall survival, cardiac radiation doses, and electrocardiographic (ECG) changes in patients treated in IDEAL-CRT, a trial of isotoxically escalated concurrent chemoradiation delivering tumor doses of 63 to 73 Gy.

METHODS AND MATERIALS

Dosimetric and survival data were analyzed for 78 patients. The whole heart, pericardium, AV node, and walls of left and right atria (LA/RA-Wall) and ventricles (LV/RV-Wall) were outlined on radiation therapy planning scans, and differential dose-volume histograms (dDVHs) were calculated. For each structure, dDVHs were approximated using the average dDVH and the 10 highest-ranked structure-specific principal components (PCs). ECGs at baseline and 6 months after radiation therapy were analyzed for 53 patients, dichotomizing patients according to presence or absence of "any ECG change" (conduction or ischemic/pericarditis-like change). All-cause death rate (DR) was analyzed from the start of treatment using Cox regression.

RESULTS

38% of patients had ECG changes at 6 months. On univariable analysis, higher scores for LA-Wall-PC6, Heart-PC6, "any ECG change," and larger planning target volume (PTV) were significantly associated with higher DR (P=.003, .009, .029, and .037, respectively). Heart-PC6 and LA-Wall-PC6 represent larger volumes of whole heart and left atrial wall receiving 63 to 69 Gy. Cardiac doses ≥63 Gy were concentrated in the LA-Wall, and consequently Heart-PC6 was highly correlated with LA-Wall-PC6. "Any ECG change," LA-Wall-PC6 scores, and PTV size were retained in the multivariable model.

CONCLUSIONS

We found associations between higher DR and conduction or ischemic/pericarditis-like changes on ECG at 6 months, and between higher DR and higher Heart-PC6 or LA-Wall-PC6 scores, which are closely related to heart or left atrial wall volumes receiving 63 to 69 Gy in this small cohort of patients.

An individualized radiation dose escalation trial in non-small cell lung cancer based on FDG-PET imaging

AIM

The aim of the study was to assess the feasibility of an individualized 18F fluorodeoxyglucose positron emission tomography (FDG-PET)-guided dose escalation boost in non-small cell lung cancer (NSCLC) patients and to assess its impact on local tumor control and toxicity.

PATIENTS AND METHODS

A total of 13 patients with stage II-III NSCLC were enrolled to receive a dose of 62.5 Gy in 25 fractions to the CT-based planning target volume (PTV; primary turmor and affected lymph nodes). The fraction dose was increased within the individual PET-based PTV (PTV_PET) using intensity modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB) until the predefined organ-at-risk (OAR) threshold was reached. Tumor response was assessed during follow-up by means of repeat FDG-PET/computed tomography. Acute and late toxicity were recorded and classified according to the CTCAE criteria (Version 4.0). Local progression-free survival was determined using the Kaplan-Meier method.

RESULTS

The average dose to PTV_PET reached 89.17 Gy for peripheral and 75 Gy for central tumors. After a median follow-up period of 29 months, seven patients were still alive, while six had died (four due to distant progression, two due to grade 5 toxicity). Local progression was seen in two patients in association with further recurrences. One and 2-year local progression free survival rates were 76.9% and 52.8%, respectively. Three cases of acute grade 3 esophagitis were seen. Two patients with central tumors developed late toxicity and died due to severe hemoptysis.

CONCLUSION

These results suggest that a non-uniform and individualized dose escalation based on FDG-PET in IMRT delivery is feasible. The doses reached were higher in patients with peripheral compared to central tumors. This strategy enables good local control to be achieved at acceptable toxicity rates. However, dose escalation in centrally located tumors with direct invasion of mediastinal organs must be performed with great caution in order to avoid severe late toxicity.

Phase II Study of a Radiotherapy Total Dose Increase in Hypoxic Lesions Identified by 18F-Misonidazole PET/CT in Patients with Non-Small Cell Lung Carcinoma (RTEP5 Study)

See an invited perspective on this article on page 1043.This multicenter phase II study investigated a selective radiotherapy dose increase to tumor areas with significant ¹⁸F-misonidazole (¹⁸F-FMISO) uptake in patients with non-small cell lung carcinoma (NSCLC). Methods: Eligible patients had locally advanced NSCLC and no contraindication to concomitant chemoradiotherapy. The ¹⁸F-FMISO uptake on PET/CT was assessed by trained experts. If there was no uptake, 66 Gy were delivered. In ¹⁸F-FMISO-positive patients, the contours of the hypoxic area were transferred to the radiation oncologist. It was necessary for the radiotherapy dose to be as high as possible while fulfilling dose-limiting constraints for the spinal cord and lungs. The primary endpoint was tumor response (complete response plus partial response) at 3 mo. The secondary endpoints were toxicity, disease-free survival (DFS), and overall survival at 1 y. The target sample size was set to demonstrate a response rate of 40% or more (bilateral α = 0.05, power 1-β = 0.95). Results: Seventy-nine patients were preincluded, 54 were included, and 34 were ¹⁸F-FMISO-positive, 24 of whom received escalated doses of up to 86 Gy. The response rate at 3 mo was 31 of 54 (57%; 95% confidence interval [CI], 43%-71%) using RECIST 1.1 (17/34 responders in the ¹⁸F-FMISO-positive group). DFS and overall survival at 1 y were 0.86 (95% CI, 0.77-0.96) and 0.63 (95% CI, 0.49-0.74), respectively. DFS was longer in the ¹⁸F-FMISO-negative patients (P = 0.004). The radiotherapy dose was not associated with DFS when adjusting for the ¹⁸F-FMISO status. One toxic death (66 Gy) and 1 case of grade 4 pneumonitis (>66 Gy) were reported. Conclusion: Our approach results in a response rate of 40% or more, with acceptable toxicity. ¹⁸F-FMISO uptake in NSCLC patients is strongly associated with poor prognosis features that could not be reversed by radiotherapy doses up to 86 Gy.

Management of stage I and II nonsmall cell lung cancer

The incidence of stage I and II nonsmall cell lung cancer is likely to increase with the ageing population and introduction of screening for high-risk individuals. Optimal management requires multidisciplinary collaboration. Local treatments include surgery and radiotherapy and these are currently combined with (neo)adjuvant chemotherapy in specific cases to improve long-term outcome. Targeted therapies and immunotherapy may also become important therapeutic modalities in this patient group. For resectable disease in patients with low cardiopulmonary risk, complete surgical resection with lobectomy remains the gold standard. Minimally invasive techniques, conservative and sublobar resections are suitable for a subset of patients. Data are emerging that radiotherapy, especially stereotactic body radiation therapy, is a valid alternative in compromised patients who are high-risk candidates for surgery. Whether this is also true for good surgical candidates remains to be evaluated in randomised trials. In specific subgroups adjuvant chemotherapy has been shown to prolong survival; however, patient selection remains important. Neoadjuvant chemotherapy may yield similar results as adjuvant chemotherapy. The role of targeted therapies and immunotherapy in early stage nonsmall cell lung cancer has not yet been determined and results of randomised trials are awaited.

Optimal design and patient selection for interventional trials using radiogenomic biomarkers: A REQUITE and Radiogenomics consortium statement

The optimal design and patient selection for interventional trials in radiogenomics seem trivial at first sight. However, radiogenomics do not give binary information like in e.g. targetable mutation biomarkers. Here, the risk to develop severe side effects is continuous, with increasing incidences of side effects with higher doses and/or volumes. In addition, a multi-SNP assay will produce a predicted probability of developing side effects and will require one or more cut-off thresholds for classifying risk into discrete categories. A classical biomarker trial design is therefore not optimal, whereas a risk factor stratification approach is more appropriate. Patient selection is crucial and this should be based on the dose-response relations for a specific endpoint. Alternatives to standard treatment should be available and this should take into account the preferences of patients. This will be discussed in detail.

PRONTOX - proton therapy to reduce acute normal tissue toxicity in locally advanced non-small-cell lung carcinomas (NSCLC): study protocol for a randomised controlled trial

Background

Primary radiochemotherapy with photons is the standard treatment for locally advanced-stage non-small cell lung cancer (NSCLC) patients. Acute radiation-induced side effects such as oesophagitis and radiation pneumonitis limit patients’ quality of life, and the latter can be potentially life-threatening. Due to its distinct physical characteristics, proton therapy enables better sparing of normal tissues, which is supposed to translate into a reduction of radiation-induced side effects.

Methods/design

This is a single-centre, prospective, randomised controlled, phase II clinical trial to compare photon to proton radiotherapy up to 66 Gy (RBE) with concomitant standard chemotherapy in patients with locally advanced-stage NSCLC. Patients will be allocated in a 1:1 ratio to photon or proton therapy, and treatment will be delivered slightly accelerated with six fractions of 2 Gy (RBE) per week.

Discussion

The overall aim of the study is to show a decrease of early and intermediate radiation-induced toxicity using proton therapy. For the primary endpoint of the study we postulate a decrease of radiation-induced side effects (oesophagitis and pneumonitis grade II or higher) from 39 to 12%. Secondary endpoints are locoregional and distant failure, overall survival and late side effects.

Trial registration

Registered at ClinicalTrials.gov with Identifier NCT02731001 on 1 April 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1679-4) contains supplementary material, which is available to authorized users.

Prognostic Factors in Stage III Non-Small-Cell Lung Cancer Patients

Aim: The objective of this study is to investigate prognostic factors affecting survival of patients undergoing concurrent or sequential chemoradiotherapy (CRT) for stage III non-small-cell lung cancer (NSCL). Methods and materials: We retrospectively reviewed the clinical records of 148 patients with advanced, inoperable stage III NSCLC, who were treated between 2007 and 2015. Results: The median survival was found to be 19 months and 3-year overall survival was 27%. Age (<65 vs ≥65 years, p=0.026), stage (IIIA vs IIIB, p=0.033), dose of radiotherapy (RT) (<60 vs ≥60 Gy, p=0.024) and treatment method (sequential chemotherapy+RT vs concurrent CRT , p=0.023) were found to be factors affecting survival in univariate analyses. Gender, histological subtype, weight loss during CRT, performance status, induction/consolidation chemotherapy and presence of comorbidities did not affect survival (p>0.050). Conclusion: Young age, stage IIIA, radiotherapy dose and concurrent chemoradiotherapy may positively affect survival in stage III NSCL cases.

[Role of functional imaging in the definition of target volumes for lung cancer radiotherapy]

Functional imaging with positron emission tomography (PET) is interesting to optimize lung radiotherapy planning, and probably to deliver a heterogeneous dose or adapt the radiation dose during treatment. Only fluorodeoxyglucose (FDG) PET-computed tomography (CT) is validated for staging lung cancer and planning radiotherapy. The optimal segmentation methods remain to be defined as well as the interest of "dose painting" from pre-treatment PET (metabolism: FDG) or hypoxia (fluoromisonidazole: FMISO) and the interest of replanning based on pertherapeutic PET.

Functional Data Analysis Applied to Modeling of Severe Acute Mucositis and Dysphagia Resulting From Head and Neck Radiation Therapy

Purpose

Current normal tissue complication probability modeling using logistic regression suffers from bias and high uncertainty in the presence of highly correlated radiation therapy (RT) dose data. This hinders robust estimates of dose-response associations and, hence, optimal normal tissue—sparing strategies from being elucidated. Using functional data analysis (FDA) to reduce the dimensionality of the dose data could overcome this limitation.

Methods and Materials

FDA was applied to modeling of severe acute mucositis and dysphagia resulting from head and neck RT. Functional partial least squares regression (FPLS) and functional principal component analysis were used for dimensionality reduction of the dose-volume histogram data. The reduced dose data were input into functional logistic regression models (functional partial least squares—logistic regression [FPLS-LR] and functional principal component—logistic regression [FPC-LR]) along with clinical data. This approach was compared with penalized logistic regression (PLR) in terms of predictive performance and the significance of treatment covariate—response associations, assessed using bootstrapping.

Results

The area under the receiver operating characteristic curve for the PLR, FPC-LR, and FPLS-LR models was 0.65, 0.69, and 0.67, respectively, for mucositis (internal validation) and 0.81, 0.83, and 0.83, respectively, for dysphagia (external validation). The calibration slopes/intercepts for the PLR, FPC-LR, and FPLS-LR models were 1.6/−0.67, 0.45/0.47, and 0.40/0.49, respectively, for mucositis (internal validation) and 2.5/−0.96, 0.79/−0.04, and 0.79/0.00, respectively, for dysphagia (external validation). The bootstrapped odds ratios indicated significant associations between RT dose and severe toxicity in the mucositis and dysphagia FDA models. Cisplatin was significantly associated with severe dysphagia in the FDA models. None of the covariates was significantly associated with severe toxicity in the PLR models. Dose levels greater than approximately 1.0 Gy/fraction were most strongly associated with severe acute mucositis and dysphagia in the FDA models.

Conclusions

FPLS and functional principal component analysis marginally improved predictive performance compared with PLR and provided robust dose-response associations. FDA is recommended for use in normal tissue complication probability modeling.

Prognostic value of blood-biomarkers related to hypoxia, inflammation, immune response and tumour load in non-small cell lung cancer - A survival model with external validation

AIM

Improve the prognostic prediction of clinical variables for non-small cell lung cancer (NSCLC), by selecting from blood-biomarkers, non-invasively describing hypoxia, inflammation and tumour load.

METHODS

Model development and validation included 182 and 181 inoperable stage I-IIIB NSCLC patients treated radically with radiotherapy (55.2%) or chemo-radiotherapy (44.8%). Least absolute shrinkage and selection operator (LASSO), selected from blood-biomarkers related to hypoxia [osteopontin (OPN) and carbonic anhydrase IX (CA-IX)], inflammation [interleukin-6 (IL-6), IL-8, and C-reactive protein (CRP)], and tumour load [carcinoembryonic antigen (CEA), and cytokeratin fragment 21-1 (Cyfra 21-1)]. Sequent model extension selected from alpha-2-macroglobulin (α2M), serum interleukin-2 receptor (sIL2r), toll-like receptor 4 (TLR4), and vascular endothelial growth factor (VEGF). Discrimination was reported by concordance-index.

RESULTS

OPN and Cyfra 21-1 (hazard ratios of 3.3 and 1.7) significantly improved a clinical model comprising gender, World Health Organization performance-status, forced expiratory volume in 1s, number of positive lymph node stations, and gross tumour volume, from a concordance-index of 0.66 to 0.70 (validation=0.62 and 0.66). Extension of the validated model yielded a concordance-index of 0.67, including α2M, sIL2r and VEGF (hazard ratios of 4.6, 3.1, and 1.4).

CONCLUSION

Improvement of a clinical model including hypoxia and tumour load blood-biomarkers was validated. New immunological markers were associated with overall survival. Data and models can be found at www.cancerdata.org (http://dx.doi.org/10.17195/candat.2016.04.1) and www.predictcancer.org.

Accelerated hypofractionated three-dimensional conformal radiation therapy (3 Gy/fraction) combined with concurrent chemotherapy for patients with unresectable stage III non-small cell lung cancer: preliminary results of an early terminated phase II trial

BACKGROUND

Increasing the biological effective dose (BED) of radiotherapy for non-small cell lung cancer (NSCLC) can increase local control rates and improve overall survival. Compared with conventional fractionated radiotherapy, accelerated hypofractionated radiotherapy can yield higher BED, shorten the total treatment time, and theoretically obtain better efficacy. However, currently, there is no optimal hypofractionated radiotherapy regimen. Based on phase I trial results, we performed this phase II trial to further evaluate the safety and preliminary efficacy of accelerated hypofractionated three-dimensional conformal radiation therapy(3-DCRT) combined with concurrent chemotherapy for patients with unresectable stage III NSCLC.

METHODS

Patients with previously untreated unresectable stage III NSCLC received 3-DCRT with a total dose of 69 Gy, delivered at 3 Gy per fraction, once daily, five fractions per week, completed within 4.6 weeks. At the same time, platinum doublet chemotherapy was applied.

RESULTS

After 12 patients were enrolled in the group, the trial was terminated early. There were five cases of grade III radiation esophagitis, of which four cases completed the radiation doses of 51 Gy, 51 Gy, 54 Gy, and 66 Gy, and one case had 16 days of radiation interruption. The incidence of grade III acute esophagitis in patients receiving an irradiation dose per fraction ≥2.7 Gy on the esophagus was 83.3% (5/6). The incidence of symptomatic grade III radiation pneumonitis among the seven patients who completed 69 Gy according to the plan was 28.6% (2/7). The median local control (LC) and overall survival (OS) were not achieved; the 1-year LC rate was 59.3%, and the 1-year OS rate was 78.6%.

CONCLUSION

For unresectable stage III NSCLC, the accelerated hypofractionated radiotherapy with a total dose of 69 Gy (3 Gy/f) combined with concurrent chemotherapy might result in severe radiation esophagitis and pneumonitis to severely affect the completion of the radiotherapy. Therefore, we considered that this regimen was infeasible. During the hypofractionated radiotherapy with concurrent chemotherapy, the irradiation dose per fraction to esophagus should be lower than 2.7 Gy. Further studies should be performed using esophageal tolerance as a metric in dose escalation protocols.

TRIAL REGISTRATION

NCT02720614, the date of registration: March 23, 2016.