Radiation Therapy Quality Assurance (RTQA) of Concurrent Chemoradiation Therapy for Locally Advanced Non-Small Cell Lung Cancer in the PROCLAIM Phase 3 Trial

Clinical impact of radiotherapy quality assurance results in contemporary cancer trials: a systematic review and meta-analysis

BACKGROUND

Radiotherapy quality assurance (RTQA) is a critical aspect of randomized controlled trials (RCTs) and is associated with validity and reproducibility of the study findings. We conducted a systematic review and meta-analysis to assess the impact of RTQA results in contemporary RCTs on patient outcomes.

METHODS

We searched MEDLINE and CENTRAL from January 2010, to April 2024, for papers that report on the impact of RTQA on patient outcomes in contemporary RCTs. We conducted random-effects meta-analyses to examine the association of radiotherapy protocol deviations with overall survival (OS), progression free survival (PFS), and locoregional recurrence (LR).

RESULTS

Of 2,723 citations, 16 publications reporting on 13 RCTs were included across various disease sites. Of 7,170 total randomized patients across 1,076 institutions in over 25 countries, 5,560 patients had radiotherapy quality data and were included in RTQA analyses. Most included RCTs (7/12; 58 %) conducted exclusively retrospective RTQA after treatment completion. Our meta-analyses found that protocol deviations may be associated with worse OS [HR = 1.65 (95 % CI: 1.23-2.22; p < 0.001)] and PFS [HR = 1.79 (95 % CI: 1.00-3.21; p = 0.03)]. No significant association was demonstrated between protocol deviations and LR [HR = 2.09 (95 % CI: 0.85-5.15; p = 0.108)].

CONCLUSIONS

Quality of radiotherapy continues to have an important, measurable impact on patient outcomes in oncology RCTs, and rigorous, real-time RTQA procedures may diminish these effects by standardizing RT. Future trials should provide patient outcome data in relation to RTQA and continue to report on the effect of protocol deviations in the context of modern RT techniques.

Efficient application of deep learning-based elective lymph node regions delineation for pelvic malignancies

BACKGROUND

While there are established international consensuses on the delineation of pelvic lymph node regions (LNRs), significant inter- and intra-observer variabilities persist. Contouring these clinical target volumes for irradiation in pelvic malignancies is both time-consuming and labor-intensive.

PURPOSE

The purpose of this study was to develop a deep learning model of pelvic LNRs delineation for patients with pelvic cancers.

METHODS

Planning computed tomography (CT) studies of 160 patients with pelvic primary malignancies (including rectal, prostate, and cervical cancer) were retrospectively collected and divided into training set (n = 120) and testing set (n = 40). Six pelvic LNRs, including abdominal presacral, pelvic presacral, internal iliac nodes, external iliac nodes, obturator nodes, and inguinal nodes were delineated by two radiation oncologists as ground truth (Gt) contours. The cascaded multi-heads U-net (CMU-net) was constructed based on the Gt contours from training cohort, which was subsequently verified in the testing cohort. The automatic delineation of six LNRs (Auto) was evaluated using dice similarity coefficient (DSC), average surface distance (ASD), 95th percentile Hausdorff distance (HD95), and a 7-point scale score.

RESULTS

In the testing set, the DSC of six pelvic LNRs by CMU-net model varied from 0.851 to 0.942, ASD from 0.381 to 1.037 mm, and HD95 from 2.025 to 3.697 mm. No significant differences were founded in these three parameters between postoperative and preoperative cases. 95.9% and 96.2% of auto delineations by CMU-net model got a score of 1-3 by two expert radiation oncologists, respectively, meaning only minor edits needed.

CONCLUSIONS

The CMU-net was successfully developed for automated delineation of pelvic LNRs for pelvic malignancies radiotherapy with improved contouring efficiency and highly consistent, which might justify its implementation in radiotherapy work flow.

Deep Learning for Automatic Gross Tumor Volumes Contouring in Esophageal Cancer Based on Contrast-Enhanced Computed Tomography Images: A Multi-Institutional Study

PURPOSE

To develop and externally validate an automatic artificial intelligence (AI) tool for delineating gross tumor volume (GTV) in patients with esophageal squamous cell carcinoma (ESCC), which can assist in neo-adjuvant or radical radiation therapy treatment planning.

METHODS AND MATERIALS

In this multi-institutional study, contrast-enhanced CT images from 580 eligible ESCC patients were retrospectively collected. The GTV contours delineated by 2 experts via consensus were used as ground truth. A 3-dimensional deep learning model was developed for GTV contouring in the training cohort and internally and externally validated in 3 validation cohorts. The AI tool was compared against 12 board-certified experts in 25 patients randomly selected from the external validation cohort to evaluate its assistance in improving contouring performance and reducing variation. Contouring performance was measured using dice similarity coefficient (DSC) and average surface distance. Additionally, our previously established radiomics model for predicting pathologic complete response was used to compare AI-generated and ground truth contours, to assess the potential of the AI contouring tool in radiomics analysis.

RESULTS

The AI tool demonstrated good GTV contouring performance in multicenter validation cohorts, with median DSC values of 0.865, 0.876, and 0.866 and median average surface distance values of 0.939, 0.789, and 0.875 mm, respectively. Furthermore, the AI tool significantly improved contouring performance for half of 12 board-certified experts (DSC values, 0.794-0.835 vs 0.856-0.881, P = .003-0.048), reduced the intra- and interobserver variations by 37.4% and 55.2%, respectively, and saved contouring time by 77.6%. In the radiomics analysis, 88.7% of radiomic features from ground truth and AI-generated contours demonstrated stable reproducibility, and similar pathologic complete response prediction performance for these contours (P = .430) was observed.

CONCLUSIONS

Our AI contouring tool can improve GTV contouring performance and facilitate radiomics analysis in ESCC patients, which indicates its potential for GTV contouring during radiation therapy treatment planning and radiomics studies.

Stereotactic ablative body radiotherapy for primary kidney cancer (TROG 15.03 FASTRACK II): a non-randomised phase 2 trial

BACKGROUND

Stereotactic ablative body radiotherapy (SABR) is a novel non-invasive alternative for patients with primary renal cell cancer who do not undergo surgical resection. The FASTRACK II clinical trial investigated the efficacy of SABR for primary renal cell cancer in a phase 2 trial.

METHODS

This international, non-randomised, phase 2 study was conducted in seven centres in Australia and one centre in the Netherlands. Eligible patients aged 18 years or older had biopsy-confirmed diagnosis of primary renal cell cancer, with only a single lesion; were medically inoperable, were at high risk of complications from surgery, or declined surgery; and had an Eastern Cooperative Oncology Group performance status of 0-2. A multidisciplinary decision that active treatment was warranted was required. Key exclusion criteria were a pre-treatment estimated glomerular filtration rate of less than 30 mL/min per 1·73 m2, previous systemic therapies for renal cell cancer, previous high-dose radiotherapy to an overlapping region, tumours larger than 10 cm, and direct contact of the renal cell cancer with the bowel. Patients received either a single fraction SABR of 26 Gy for tumours 4 cm or less in maximum diameter, or 42 Gy in three fractions for tumours more than 4 cm to 10 cm in maximum diameter. The primary endpoint was local control, defined as no progression of the primary renal cell cancer, as evaluated by the investigator per Response Evaluation Criteria in Solid Tumours (version 1.1). Assuming a 1-year local control of 90%, the null hypothesis of 80% or less was considered not to be worthy of proceeding to a future randomised controlled trial. All patients who commenced trial treatment were included in the primary outcome analysis. This trial is registered with ClinicalTrials.gov, NCT02613819, and has completed accrual.

FINDINGS

Between July 28, 2016, and Feb 27, 2020, 70 patients were enrolled and initiated treatment. Median age was 77 years (IQR 70-82). Before enrolment, 49 (70%) of 70 patients had documented serial growth on initial surveillance imaging. 49 (70%) of 70 patients were male and 21 (30%) were female. Median tumour size was 4·6 cm (IQR 3·7-5·5). All patients enrolled had T1-T2a and N0-N1 disease. 23 patients received single-fraction SABR of 26 Gy and 47 received 42 Gy in three fractions. Median follow-up was 43 months (IQR 38-60). Local control at 12 months from treatment commencement was 100% (p<0·0001). Seven (10%) patients had grade 3 treatment-related adverse events, with no grade 4 adverse events observed. Grade 3 treatment-related adverse events were nausea and vomiting (three [4%] patients), abdominal, flank, or tumour pain (four [6%]), colonic obstruction (two [3%]), and diarrhoea (one [1%]). No treatment-related or cancer-related deaths occurred.

INTERPRETATION

To our knowledge, this is the first multicentre prospective clinical trial of non-surgical definitive therapy in patients with primary renal cell cancer. In a cohort with predominantly T1b or larger disease, SABR was an effective treatment strategy with no observed local failures or cancer-related deaths. We observed an acceptable side-effect profile and renal function after SABR. These outcomes support the design of a future randomised trial of SABR versus surgery for primary renal cell cancer.

FUNDING

Cancer Australia Priority-driven Collaborative Cancer Research Scheme.

Towards automated organs at risk and target volumes contouring: Defining precision radiation therapy in the modern era

Precision radiotherapy is a critical and indispensable cancer treatment means in the modern clinical workflow with the goal of achieving "quality-up and cost-down" in patient care. The challenge of this therapy lies in developing computerized clinical-assistant solutions with precision, automation, and reproducibility built-in to deliver it at scale. In this work, we provide a comprehensive yet ongoing, incomplete survey of and discussions on the recent progress of utilizing advanced deep learning, semantic organ parsing, multimodal imaging fusion, neural architecture search and medical image analytical techniques to address four corner-stone problems or sub-problems required by all precision radiotherapy workflows, namely, organs at risk (OARs) segmentation, gross tumor volume (GTV) segmentation, metastasized lymph node (LN) detection, and clinical tumor volume (CTV) segmentation. Without loss of generality, we mainly focus on using esophageal and head-and-neck cancers as examples, but the methods can be extrapolated to other types of cancers. High-precision, automated and highly reproducible OAR/GTV/LN/CTV auto-delineation techniques have demonstrated their effectiveness in reducing the inter-practitioner variabilities and the time cost to permit rapid treatment planning and adaptive replanning for the benefit of patients. Through the presentation of the achievements and limitations of these techniques in this review, we hope to encourage more collective multidisciplinary precision radiotherapy workflows to transpire.

Lung SBRT credentialing in the Canadian OCOG-LUSTRE randomized trial

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We report on the credentialing experience of a Phase III trial of SBRT versus hypofractionated RT for stage I lung cancer.

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Elements included a site survey, phantom test, and a standardized case for a peripheral and central tumour.

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Approximately 1/3 of plans required resubmission due to major deviations,but were not biased towards centre experience versus not.

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There was contour variability demonstrated, whereas target coverage and dose constraints were largely per-protocol.

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Such an exercise is important for studies that rely on high precision radiotherapy, and to ensure optimal trial quality.

Purpose

To report on the Stereotactic Body Radiation Therapy (SBRT) credentialing experience during the Phase III Ontario Clinical Oncology Group (OCOG) LUSTRE trial for stage I non-small cell lung cancer.

Methods

Three credentialing requirements were required in this process: (a) An institutional technical survey; (b) IROC (Imaging and Radiation Oncology Core) thoracic phantom end-to-end test; and (c) Contouring and completion of standardized test cases using SBRT for one central and one peripheral lung cancer, compared against the host institution as the standard. The main hypotheses were that unacceptable variation would exist particularly in OAR definition across all centres, and that institutions with limited experience in SBRT would be more likely to violate per-protocol guidelines.

Results

Fifteen Canadian centres participated of which 8 were new, and 7 were previously established (≥2 years SBRT experience), and all successfully completed surveys and IROC phantom testing. Of 30 SBRT test plans, 10 required replanning due to major deviations, with no differences in violations between new and established centres (p = 0.61). Mean contouring errors were highest for brachial plexus in the central (C) case (12.55 ± 6.62 mm), and vessels in the peripheral (P) case (13.01 ± 12.55 mm), with the proximal bronchial tree (PBT) (2.82 ± 0.78 C, 3.27 ± 1.06 P) as another variable structure. Mean dice coefficients were lowest for plexus (0.37 ± 0.2 C, 0.37 ± 0.14 P), PBT (0.77 ± 0.06 C, 0.75 ± 0.09 P), vessels (0.69 ± 0.29 C, 0.64 ± 0.31 P), and esophagus (0.74 ± 0.04 C, 0.76 ± 0.04 P). All plans passed per-protocol planning target volume (PTV) coverage and maximum/volumetric organs-at-risk constraints, although variations existed in dose gradients within and outside the target.

Conclusions

Clear differences exist in both contouring and planning with lung SBRT, regardless of centre experience. Such an exercise is important for studies that rely on high precision radiotherapy, and to ensure that implications on trial quality and outcomes are as optimal as possible.

Evaluation of auto-segmentation for EBRT planning structures using deep learning-based workflow on cervical cancer

Deep learning (DL) based approach aims to construct a full workflow solution for cervical cancer with external beam radiation therapy (EBRT) and brachytherapy (BT). The purpose of this study was to evaluate the accuracy of EBRT planning structures derived from DL based auto-segmentation compared with standard manual delineation. Auto-segmentation model based on convolutional neural networks (CNN) was developed to delineate clinical target volumes (CTVs) and organs at risk (OARs) in cervical cancer radiotherapy. A total of 300 retrospective patients from multiple cancer centers were used to train and validate the model, and 75 independent cases were selected as testing data. The accuracy of auto-segmented contours were evaluated using geometric and dosimetric metrics including dice similarity coefficient (DSC), 95% hausdorff distance (95%HD), jaccard coefficient (JC) and dose-volume index (DVI). The correlation between geometric metrics and dosimetric difference was performed by Spearman’s correlation analysis. The right and left kidney, bladder, right and left femoral head showed superior geometric accuracy (DSC: 0.88–0.93; 95%HD: 1.03 mm–2.96 mm; JC: 0.78–0.88), and the Bland–Altman test obtained dose agreement for these contours (P > 0.05) between manual and DL based methods. Wilcoxon’s signed-rank test indicated significant dosimetric differences in CTV, spinal cord and pelvic bone (P < 0.001). A strong correlation between the mean dose of pelvic bone and its 95%HD (R = 0.843, P < 0.001) was found in Spearman’s correlation analysis, and the remaining structures showed weak link between dosimetric difference and all of geometric metrics. Our auto-segmentation achieved a satisfied agreement for most EBRT planning structures, although the clinical acceptance of CTV was a concern. DL based auto-segmentation was an essential component in cervical cancer workflow which would generate the accurate contouring.

Treatment planning comparison in the PROTECT-trial randomising proton versus photon beam therapy in oesophageal cancer: results from eight european centres

PURPOSE

To compare dose distributions and robustness in treatment plans from eight European centres in preparation for the European randomized phase-III PROTECT-trial investigating the effect of proton therapy (PT) versus photon therapy (XT) for oesophageal cancer.

MATERIALS AND METHODS

All centres optimized one PT and one XT nominal plan using delineated 4DCT scans for four patients receiving 50.4Gy(RBE) in 28 fractions. Target volume receiving 95% of prescribed dose (V95%_iCTVtotal) should be >99%. Robustness towards setup, range, and respiration was evaluated. The plans were recalculated on a surveillance 4DCT (sCT) acquired at fraction ten and robustness evaluation was performed to evaluate the effect of respiration and inter-fractional anatomical changes.

RESULTS

All PT and XT plans complied with V95%_iCTVtotal>99% for the nominal plan and V95%_iCTVtotal>97% for all respiratory and robustness scenarios. Lung and heart dose varied considerably between centres for both modalities. The difference in mean lung dose and mean heart dose between each pair of XT and PT plans was in median [range] 4.8Gy [1.1;7.6] and 8.4Gy [1.9;24.5], respectively. Patients B and C showed large inter-fractional anatomical changes on sCT. For patient B, the minimum V95%_iCTVtotal in the worst-case robustness scenario was 45% and 94% for XT and PT, respectively. For patient C, the minimum V95%_iCTVtotal was 57% and 72% for XT and PT, respectively. Patient A and D showed minor inter-fractional changes and the minimum V95%_iCTVtotal was >85%.

CONCLUSION

Large variability in dose to the lungs and heart was observed for both modalities. Inter-fractional anatomical changes led to larger target dose deterioration for XT than PT plans.

Prognostic significance of baseline neutrophil-lymphocyte ratio in patients with non-small-cell lung cancer: a pooled analysis of open phase III clinical trial data

Aim: This study aimed to assess survival and hematological prognostic indicators of patients with non-small-cell lung cancer (NSCLC). Material & methods: Through the Project Data Sphere portal, two phase III clinical trial datasets were downloaded to analyze survival outcomes and related risk factors. Results: The median progression-free survival and overall survival of 756 patients with stage III-IV NSCLC were 6.2 and 14.2 months, respectively. In multivariate Cox analysis, high baseline neutrophil-lymphocyte ratio (NLR; ≥3.8) was associated with worse progression-free survival (hazard ratio: 1.37; p = 0.0004) and overall survival (hazard ratio: 1.65; p < 0.0001). In addition, it exerted an unfavorable impact on survival across multiple subgroups. Conclusions: NLR, a powerful inflammatory and immunologic indicator, is an independent prognostic indicator in patients with advanced NSCLC.

Multi-institutional feasibility study of intensity-modulated radiotherapy with chemotherapy for locally advanced non-small cell lung cancer

BACKGROUND

This multi-institutional clinical trial evaluated the feasibility of intensity-modulated radiotherapy (IMRT) for patients with locally advanced non-small cell lung cancer (NSCLC).

METHODS

The major inclusion criteria were clinical stage III NSCLC, age 20-74 years, and Eastern Cooperative Oncology Group performance status 0-1. Patients were treated with either cisplatin + S-1 (CS; four cycles every 4 weeks) or carboplatin + paclitaxel (CP; administered weekly with thoracic radiotherapy [RT], plus two consolidation cycles) concurrently with IMRT (60 Gy in 30 fractions). The primary endpoint was a treatment completion rate, defined as at least two cycles of CS or five cycles of CP during IMRT and completing 60 Gy IMRT within 56 days after the start of treatment, assumed its 90% confidence interval exceeds 60%. RT quality assurance was mandatory for all the patients.

RESULTS

Twenty-two patients were registered. One patient withdrew due to pulmonary infection before starting treatment. RT plans were reviewed and none was judged as a protocol violation. Grade 2 and 3 pneumonitis occurred in four (19%) and one (5%) patients, respectively. Seventeen patients met the primary endpoint, with a treatment completion rate of 77.3% (90% confidence interval [CI] 58.0%-90.6%). Four patients failed to complete chemotherapy due to chemotherapy-related adverse events, but 20 patients completed IMRT. There were no treatment-related deaths. The 2-year progression-free and overall survival rates were 31.8% (95% CI 17.3%-58.7%) and 77.3% (95% CI 61.6%-96.9%), respectively.

CONCLUSION

The treatment completion rate did not meet the primary endpoint, but 20 of 22 patients completed IMRT.

Radiation oncology peer review in Australia and New Zealand

Peer review is a part of high quality care within radiation oncology, designed to achieve the best outcomes for patients. We discuss the importance of and evidence for peer review in clinical practice. The Royal Australia and New Zealand College of Radiologists (RANZCR) has evolved a Peer Review Assessment Tool (PRAT) since 1999. We report the results of a RANZCR faculty survey conducted in radiation oncology facilities across Australia and New Zealand to guide the 2019 PRAT revision process, and discuss the development and implementation of the 2019 PRAT. Peer-review processes are now mandated as a component of Australian and International Quality Standards. Several practical recommendations might address challenges for effective implementation of peer review process in routine clinical practice. This includes prioritising tumour sites and treatment techniques for peer review within the time and resources constraints of each institution, improving resource allocation, ensuring optimal timing and duration for peer review meetings, and adopting multi-centre virtual peer review meeting where necessary.

Postoperative radiotherapy for patients with completely resected stage IIIA-N2 non-small cell lung cancer: opt-in or opt-out

The role of adjuvant radiotherapy in completely resected pIIIA-N2 non-small cell lung cancer (NSCLC) has long been debated. Evidence from previous retrospective and prospective studies showed that postoperative radiotherapy could reduce the incidence of local recurrence and prolong disease-free survival, while two recently reported randomized controlled trials (lung ART and PORT-C) both demonstrated no survival benefit of postoperative radiotherapy. The great gap between our knowledge and reality has made us rethink the value of postoperative radiotherapy. In this mini review, we elaborate on the role of postoperative radiotherapy in completely resected pIIIA-N2 NSCLC.

The radiotherapy quality assurance gap among phase III cancer clinical trials

PURPOSE

Quality assurance (QA) practices improve the quality level of oncology trials by ensuring that the protocol is followed and the results are valid and reproducible. This study investigated the utilization of QA among randomized controlled trials that involve radiotherapy (RT).

METHODS AND MATERIALS

We searched ClinicalTrials.gov in February 2020 for all phase III oncology randomized clinical trials (RCTs). These trials were screened for RT-specific RCTs that had published primary trial results. Information regarding QA in each trial was collected from the study publications and trial protocol if available. Two individuals independently performed trial screening and data collection. Pearson's Chi-square tests analyses were used to assess factors that were associated with QA inclusion in RT trials.

RESULTS

Forty-two RCTs with RT as the primary intervention or as a mandatory component of the protocol were analyzed; the earliest was started in 1994 and one trial was still active though not recruiting. Twenty-nine (69%) trials mandated RT quality assurance (RTQA) practices as part of the trial protocol, with 19 (45%) trials requiring institutional credentialing. Twenty-one (50%) trials published protocol deviation outcomes. Clinical trials involving advanced radiation techniques (IMRT, VMAT, SRS, SBRT) did not include more RTQA than trials without these advanced techniques (73% vs. 65%, p = 0.55). Trials that reported protocol deviation outcomes were associated with mandating RTQA in their protocols as compared to trials that did not report these outcomes (100% vs. 38%, p < 0.001).

CONCLUSIONS

There is a lack of RTQA utilization and transparency in RT clinical trials. It is imperative for RT trials to include increased QA for safe, consistent, and high-quality RT planning and delivery.

Relationship between Treatment Plan Dosimetry, Toxicity, and Survival following Intensity-Modulated Radiotherapy, with or without Chemotherapy, for Stage III Inoperable Non-Small Cell Lung Cancer

Simple Summary

Various radiotherapy treatment methods are available for patients with stage III non-small-cell lung cancer (NSCLC). A multidisciplinary tumor board review is recommended to determine the best treatment strategy. In fit patients with inoperable tumors, concurrent chemoradiotherapy (cCRT) is preferred over sequential CRT (sCRT), due to better survival. Nonetheless, the use of cCRT in stage III NSCLC varies significantly, with concerns about treatment toxicity being a contributory factor. Many reports describing the relationship between overall survival, toxicity, and dosimetry in patients with locally advanced NSCLC are based on clinical trials, with strict criteria for patient selection, including good performance status, pulmonary function, etc. These trials have not always mandated the use of IMRT/VMAT. We therefore performed an institutional analysis to study the relationship between dosimetric parameters and overall survival and toxicity in patients with stage III NSCLC treated with IMRT/VMAT-based techniques in routine clinical practice.

Abstract

Concurrent chemoradiotherapy (cCRT) is the preferred treatment for stage III NSCLC because surgery containing multimodality treatment is often not appropriate. Alternatives, often for less fit patients, include sequential CRT and RT alone. Many reports describing the relationship between overall survival (OS), toxicity, and dosimetry are based on clinical trials, with strict criteria for patient selection. We performed an institutional analysis to study the relationship between dosimetric parameters, toxicity, and OS in inoperable patients with stage III NSCLC treated with (hybrid) IMRT/VMAT-based techniques in routine clinical practice. Eligible patients had undergone treatment with radical intent using cCRT, sCRT, or RT alone, planned to a total dose ≥ 50 Gy delivered in ≥15 fractions. All analyses were performed for two patient groups, (1) cCRT (n = 64) and (2) sCRT/RT (n = 65). The toxicity rate differences between the two groups were not significant, and OS was 29 and 17 months, respectively. For sCRT/RT, no dosimetric factors were associated with OS, whereas for cCRT, PTV-volume, esophagus V50 Gy, and contralateral lung V5 Gy were associated. cCRT OS was significantly lower in patients with esophagitis ≥ G2. The overall rate of ≥G3 pneumonitis was low (3%), and the rate of high-grade esophagitis the OS in this real-world patient population was comparable to those reported in clinical trials. Based on this hypothesis-generating data, more aggressive esophageal sparing merits consideration. Institutional auditing and benchmarking of the planning strategy, dosimetry, and outcome have an important role to play in the continuous quality improvement process.

Impact of radiotherapy protocol adherence in NSCLC patients treated with concurrent chemoradiation: RTQA results of the PET-Plan trial

INTRODUCTION

The success of intensification and personalisation of the curative treatment of non-small cell lung cancer (NSCLC) is strongly associated with the precision in radiotherapy. Here, we evaluate the impact of radiotherapy protocol adherence in a prospective multicentre trial.

METHODS

In the open-label, randomised, controlled PET-Plan trial, patients with inoperable NSCLC were randomized at a 1:1 ratio regarding the target volume delineation informed by ¹F-FDG PET and CT plus elective nodal irradiation (arm A) or target volumes informed by PET alone (arm B) and received iso-toxically dose-escalated concurrent chemoradiation. The prospectively organised quality assurance program (RTQA) included individual case review by predefined criteria. For evaluation, protocol adherence was scored as per protocol (pP), with minor (miD), intermediate (inD) and major (maD) deviations. In order to exclude biases through patients who discontinued treatment, patients who received ≥60 Gy were additionally analysed.

RESULTS

Between 05/2009-11/2016, 205 patients were randomized, 204 patients started treatment according to protocol of which 31 (15%) patients had maD. Patients with maD had an inferior overall survival (OS) (HR 2.9, 95% CI 1.8-4.4, p < 0.0001) and a higher risk of loco-regional progression (HR 5.7, 95% CI 2.7-11.1, p < 0.0001). These results were significant also in the subgroup of patients receiving ≥ 60 Gy. Patients with maD concerning normal tissue delineation and/or dose constraints had a worse OS (p = 0.006) although no higher incidence of grade ≥ 3 toxicities.

CONCLUSIONS

Non-adherence to the radiotherapy protocol was associated with an inferior OS and loco-regional control. These results underline the importance of RTQA.

Challenges in the target volume definition of lung cancer radiotherapy

Radiotherapy, with or without systemic treatment has an important role in the management of lung cancer. In order to deliver the treatment accurately, the clinician must precisely outline the gross tumour volume (GTV), mostly on computed tomography (CT) images. However, due to the limited contrast between tumour and non-malignant changes in the lung tissue, it can be difficult to distinguish the tumour boundaries on CT images leading to large interobserver variation and differences in interpretation. Therefore the definition of the GTV has often been described as the weakest link in radiotherapy with its inaccuracy potentially leading to missing the tumour or unnecessarily irradiating normal tissue. In this article, we review the various techniques that can be used to reduce delineation uncertainties in lung cancer.

Deep diving in the PACIFIC: Practical issues in stage III non-small cell lung cancer to avoid shipwreck

After publication of the PACIFIC trial results, immune checkpoint inhibitor-based immunotherapy was included in the treatment algorithm of locally advanced non-small cell lung cancer (NSCLC). The PACIFIC trial demonstrated that 12 mo of durvalumab consolidation therapy after radical-intent platinum doublet chemotherapy with concomitant radiotherapy improved both progression-free survival and overall survival in patients with unresectable stage III NSCLC. This is the first treatment in decades to successfully improve survival in this clinical setting, with manageable toxicity and without deterioration in quality of life. The integration of durvalumab in the management of locally advanced NSCLC accentuates the need for multidisciplinary, coordinated decision-making among lung cancer specialists, bringing new challenges and controversies as well as important changes in clinical work routines. The aim of the present article is to review-from a practical, multidisciplinary perspective-the findings and implications of the PACIFIC trial. We evaluate the immunobiological basis of durvalumab as well as practical aspects related to programmed cell death ligand 1 determination. In addition, we comprehensively assess the efficacy and toxicity data from the PACIFIC trial and discuss the controversies and practical aspects of incorporating durvalumab into routine clinical practice. Finally, we discuss unresolved questions and future challenges. In short, the present document aims to provide clinicians with a practical guide for the application of the PACIFIC regimen in routine clinical practice.

Association of Planning Target Volume with Patient Outcome in Inoperable Stage III NSCLC Treated with Chemoradiotherapy: A Comprehensive Single-Center Analysis

Inoperable stage III non-small cell lung cancer (NSCLC) represents a highly heterogeneous patient cohort. Multimodal treatment approaches including radiotherapy have been the new standard of care, with promising outcomes. The planning target volume (PTV), including the primary tumor, involved lymph node stations and safety margins, can vary widely. In order to evaluate the impact of the PTV for overall survival (OS), progression-free survival (PFS) and loco-regional control, we analyzed retrospective and prospective data of 122 consecutive patients with inoperable stage III NSCLC treated with CRT. The majority of patients (93%) received a total dose ≥ 60 Gy and 92% of all patients were treated with concurrent or sequential chemotherapy. Median follow-up for the entire cohort was 41.2 (range: 3.7-108.4) months; median overall survival (OS) reached 20.9 (95% CI: 14.5-27.3) months. PTVs from 500 to 800 ccm were evaluated for their association with survival in a univariate analysis. In a multivariate analysis including age, gender, total radiation dose and histology, PTV ≥ 700 ccm remained a significant prognosticator of OS (HR: 1.705, 95% CI: 1.071-2.714, p = 0.025). After propensity score matching (PSM) analysis with exact matching for Union internationale contre le cancer (UICC) TNM Classification (7th ed.)T- and N-stage, patients with PTV < 700 ccm reached a median PFS and OS of 11.6 (95% CI: 7.3-15.9) and 34.5 (95% CI: 25.6-43.4) months vs. 6.2 (95% CI: 3.1-9.3) (p = 0.057) and 12.7 (95% CI: 8.5-16.9) (p < 0.001) months in patients with PTV ≥ 700 ccm, respectively. Inoperable stage III NSCLC patients with PTV ≥ 700 ccm had significantly detrimental outcomes after conventionally fractionated CRT. PTV should be considered as a stratification factor in multimodal clinical trials for inoperable stage III NSCLC.

Artificial intelligence in radiation oncology

Artificial intelligence (AI) has the potential to fundamentally alter the way medicine is practised. AI platforms excel in recognizing complex patterns in medical data and provide a quantitative, rather than purely qualitative, assessment of clinical conditions. Accordingly, AI could have particularly transformative applications in radiation oncology given the multifaceted and highly technical nature of this field of medicine with a heavy reliance on digital data processing and computer software. Indeed, AI has the potential to improve the accuracy, precision, efficiency and overall quality of radiation therapy for patients with cancer. In this Perspective, we first provide a general description of AI methods, followed by a high-level overview of the radiation therapy workflow with discussion of the implications that AI is likely to have on each step of this process. Finally, we describe the challenges associated with the clinical development and implementation of AI platforms in radiation oncology and provide our perspective on how these platforms might change the roles of radiotherapy medical professionals.

Development of Best Practices of Peer Review for Lung Radiation Therapy

PURPOSE

Peer review (PR) is an important component in ensuring high-quality lung radiotherapy (RT) plans. However, there are inconsistencies in the extent, timing, and minimum requirements for PR. We sought to develop guidelines of best practices for PR in curative lung RT through an expert consensus process.

METHODS

A modified Delphi process was conducted that consisted of an initial review by a dedicated steering committee followed by a pan-Canadian, multidisciplinary Delphi panel with 3 rounds (premeeting survey, face-to-face meeting, and postmeeting ratification survey). Candidate PR elements were ranked by importance and stratified by treatment of locally advanced (LA) disease with conventional RT or stereotactic ablative body RT (SABR) for early-stage disease.

RESULTS

For the LA case, 6 elements (indications for RT, gross tumor volume [GTV], clinical target volume [CTV], internal target volume [ITV], dose/fractionation, and normal lung dosimetry) were considered as essential PR elements. Of these, 90%-100% of the panel endorsed them to be important to PR, and 80% believed that the PR should be done by a second radiation oncologist (RO). In the SABR case, 6 PR elements (indications for RT, GTV, CTV/ITV, organs at risk contours, dose/fractionation, and composite plan review) were deemed essential. Of these, 90%-100% of panel members believed these elements to be important to PR and unanimously agreed that PR should be done by a second RO.

CONCLUSION

A suite of PR elements for lung RT has been developed and endorsed with high consensus. This suite should serve as a basis to help to harmonize PR practices across centers and to help to develop novel PR approaches going forward.

Immune checkpoint-inhibitors and chemoradiation in stage III unresectable non-small cell lung cancer

Lung cancer resulted in an estimated 1.8 million deaths worldwide in 2018 and approximately 20% of patients with non-small cell lung cancer (NSCLC) are diagnosed with stage III unresectable disease. Phase III data from the PACIFIC trial show significantly improved progression-free survival for the checkpoint-inhibitor durvalumab given as consolidation following definitive chemoradiotherapy (cCRT). Overall survival results from this study have now been reported, along with outcomes from other phase II trials. A thorough review of the efficacy and safety of checkpoint-inhibitors used in conjunction with cCRT for stage III unresectable NSCLC is needed. Published and presented literature on phase II and III data was identified using the key search terms "non-small cell lung cancer" AND "checkpoint-inhibitors" (OR respective aliases). One randomized phase III clinical trial and three phase II trials reporting outcomes of checkpoint-inhibitors in conjunction with cCRT for stage III unresectable NSCLC were identified. PACIFIC reported significantly improved overall survival for consolidation durvalumab following cCRT compared with placebo. Although discontinuation due to adverse events (AEs) was higher with durvalumab, rates of grade 3/4 pneumonitis or radiation pneumonitis were low and comparable between arms. Results from phase II trials also show promising activity for other checkpoint-inhibitors and alternative sequencing strategies, although these need to be confirmed in a randomized context. Preliminary data suggest differences in the safety profiles between PD-1 and PD-L1 inhibitors. Currently, the role of PD-L1 expression levels for patient selection in this setting remains unclear, and durvalumab should be administered on an individual basis in patients with known driver mutations. Consolidation durvalumab following cCRT significantly improves overall survival with an acceptable safety profile in patients with stage III unresectable NSCLC, now representing a new standard of care.