Radiotherapy and Oncology最新文献

Treatments at ultra-high dose rate (UHDR) have the potential to improve the therapeutic index of radiation therapy (RT) by sparing normal tissues compared to conventional dose rate irradiations. Insufficient and inconsistent reporting in physics and dosimetry of preclinical and translational studies may have contributed to a reproducibility crisis of radiobiological data in the field. Consequently, the development of a common terminology, as well as common recording, reporting, dosimetry, and metrology standards is required. In the context of UHDR irradiations, the temporal dose delivery parameters are of importance, and under-reporting of these parameters is also a concern.This work proposes a standardization of terminology, recording, and reporting to enhance comparability of both preclinical and clinical UHDR studies and and to allow retrospective analyses to aid the understanding of the conditions which give rise to the FLASH effect.

Purpose

Substantiating data guiding clinical decision making in locally recurrent rectal cancer (LRRC) is lacking, specifically in target volume (TV) definition for chemoradiotherapy (CRT). A case-by-case review of local re-recurrences (re-LRRC) after multimodal treatment for LRRC was performed, to determine location of re-LRRC and assess whether treatment could have been improved.

Methods

All patients treated with curative intent for LRRC at the Catharina Hospital Eindhoven from October 2016 onwards, in whom complete imaging of (re-)LRRC and radiotherapy was available, were retrieved. Patients were discussed in plenary meetings with expert colorectal surgeons, radiation oncologists and radiologists. Each case was classified based on re-LRRC location, whether it was in accordance with the (current) radiotherapy protocol, and whether multimodal management would have been different in retrospect.

Results

Thirty-three cases were discussed. LRRC treatment was deemed suboptimal in 17/33 patients, due to different target volumes (13/17) and/or different surgery (9/17). 15/33 (46 %) of re-LRRC developed in-field of the prior radiotherapy TV, possibly showing RT-resistant disease. Other re-LRRCs developed out-field (n = 5, 15 %), marginally (n = 6, 18 %), or in a combined fashion (n = 7, 21 %). In retrospect, 48 % of cases were irradiated in line with current TV recommendations. TVs of 13/33 cases would have been altered if irradiated today.

Conclusion

This study highlights room for improvement within current standard-ofcare treatment for LRRC. Different surgical management or TVs may have improved outcome in up to half of discussed cases. Further delineation guideline development, incorporating the results from this study, may improve oncological outcome, specifically local control, for LRRC patients.

Background and purpose

Magnetic resonance (MR)-guided radiotherapy (MRgRT) enhances treatment precision and adaptive capabilities, potentially supporting a simulation-free (sim-free) workflow. This work reports the first clinical implementation of a sim-free workflow using the MR-Linac for prostate cancer patients treated with stereotactic ablative radiotherapy (SABR).

Materials and methods

Fifteen patients who had undergone a prostate-specific membrane antigen positron emission tomography/CT (PSMA-PET/CT) scan as part of diagnostic workup were included in this work. Two reference plans were generated per patient: one using PSMA-PET/CT (sim-free plan) and the other using standard simulation CT (simCT plan). Dosimetric evaluations included comparisons between simCT, sim-free, and first fraction plans. Timing measurements were conducted to assess durations for both simCT and sim-free pre-treatment workflows.

Results

All 15 patients underwent successful treatment using a sim-free workflow. Dosimetric differences between simCT, sim-free, and first fraction plans were minor and within acceptable clinical limits, with no major violations of standardised criteria. The sim-free workflow took on average 130 min, while the simCT workflow took 103 min.

Conclusion

This work demonstrates the feasibility and benefits of sim-free MR-guided adaptive radiotherapy for prostate SABR, representing the first reported clinical experience in an ablative setting. By eliminating traditional simulation scans, this approach reduces patient burden by minimising hospital visits and enhances treatment accessibility.

Purpose

We sought to determine the association between multidisciplinary team (MDT) quality and survival of patients with locally advanced rectal cancer.

Methods

In a post hoc analysis of the randomized phase III STELLAR trial, 464 patients with distal or middle-third, clinical tumor category cT3-4 and/or regional lymph node-positive rectal cancer who completed surgery were evaluated. Disease-free survival (DFS) and Overall survival (OS) were stratified by Multidisciplinary team (MDT) quality, which was also included in the univariable and multivariable analyses of DFS and OS.

Results

According to the univariable analyses, a significantly worse DFS was associated with a fewer specialized medical disciplines participating in MDT (<5 vs ≥ 5; P=0.049),a lower frequency of MDT meetings (<once a week vs ≥ once a week; P=0.021) and a smaller MDT annual discussion volume of rectal cancer (≤200 vs > 200; P=0.039). In addition, a lower number of specialized medical disciplines participating in MDT (<5 vs ≥ 5; P<0.001), a lower frequency of MDT meetings (<once a week vs ≥ once a week; P<0.001) and a smaller MDT annual discussion volume of rectal cancer (≤200 vs > 200; P=0.001) were the variables associated with OS. These 3 factors were considered when assessing MDT quality, which was classified into 2 categories: high quality or general quality. Patients treated in hospitals with high MDT quality had longer 3-year OS (90.5 % vs 78.1 %; P=0.001) and similar 3-year DFS (70.3 % vs 61.3 %; P=0.109) compared to those treated in hospitals of the general MDT quality group. Furthermore, multivariable analyses revealed a significance for DFS (HR, 1.648; 95 % CI, 1.143–2.375; P=0.007) and OS (HR, 2.771; 95 % CI, 1.575–4.877; P<0.001) in MDT quality.

Conclusions

The use of hospitals with optimized multidisciplinary infrastructure had a significant influence on survival of patients with locally advanced rectal cancer.

Background

Stereotactic arrhythmia radioablation (STAR) is a therapeutic option for ventricular tachycardia (VT) where catheter-based ablation is not feasible or has previously failed. Target definition and its transfer from electro-anatomic maps (EAM) to radiotherapy treatment planning systems (TPS) is challenging and operator-dependent. Software solutions have been developed to register EAM with cardiac CT and semi-automatically transfer 2D target surface data into 3D CT volume coordinates. Results of a cross-validation study of two conceptually different software solutions using data from the RAVENTA trial (NCT03867747) are reported.

Methods

Clinical Target Volumes (CTVs) were created from target regions delineated on EAM using two conceptually different approaches by separate investigators on data of 10 patients, blinded to each other’s results. Targets were transferred using 3D-3D registration and 2D-3D registration, respectively. The resulting CTVs were compared in a core-lab using two complementary analysis software packages for structure similarity and geometric characteristics.

Results

Volumes and surface areas of the CTVs created by both methods were comparable: 14.88 ± 11.72 ml versus 15.15 ± 11.35 ml and 44.29 ± 33.63 cm² versus 46.43 ± 35.13 cm². The Dice-coefficient was 0.84 ± 0.04; median surface-distance and Hausdorff-distance were 0.53 ± 0.37 mm and 6.91 ± 2.26 mm, respectively. The 3D-center-of-mass difference was 3.62 ± 0.99 mm. Geometrical volume similarity was 0.94 ± 0.05 %.

Conclusion

The STAR targets transferred from EAM to TPS using both software solutions resulted in nearly identical 3D structures. Both solutions can be used for QA (quality assurance) and EAM-to-TPS transfer of STAR-targets. Semi-automated methods could potentially help to avoid mistargeting in STAR and offer standardized workflows for methodically harmonized treatments.

Background and Purpose

To evaluate the impact of a deep learning (DL)-assisted interactive contouring tool on inter-observer variability and the time taken to complete tumour contouring.

Materials and Methods

Nine clinicians contoured the gross tumour volume (GTV) using the PET-CT scans of 10 non-small cell lung cancer (NSCLC) patients, either using DL-assisted or manual contouring tools. After contouring a case using one contouring method, the same case was contoured one week later using the other method. The contours and time taken were compared.

Results

Use of the DL-assisted tool led to a statistically significant decrease in active contouring time of 23 % relative to the standard manual segmentation method (p < 0.01). The mean observation time for all clinicians and cases made up nearly 60 % of interaction time for both contouring approaches. On average the time spent contouring per case was reduced from 22 min to 19 min when using the DL-assisted tool. Additionally, the DL-assisted tool reduced contour variability in the parts of tumour where clinicians tended to disagree the most, while the consensus contour was similar whichever of the two contouring approaches was used.

Conclusions

A DL-assisted interactive contouring approach decreased active contouring time and local inter-observer variability when used to delineate lung cancer GTVs compared to a standard manual method. Integration of this tool into the clinical workflow could assist clinicians in contouring tasks and improve contouring efficiency.

Purpose

The aim of this secondary analysis of the prospective randomized phase 2 PET-Plan trial (ARO-2009-09; NCT00697333) was to evaluate the impact of mediastinal tumor burden and lymphatic spread in patients with locally advanced non-small-cell lung cancer (NSCLC).

Methods

All patients treated per protocol (n = 172) were included. Patients received isotoxically dose-escalated chemoradiotherapy up to a total dose of 60–74 Gy in 30–37 fractions, aiming as high as possible while adhering to normal tissue constraints. Radiation treatment (RT) planning was based on an ¹⁸F-FDG PET/CT targeting all lymph node (LN) stations containing CT positive LNs (i.e. short axis diameter > 10 mm), even if PET-negative (arm A) or targeting only LN stations containing PET-positive nodes (arm B). LN stations were classified into echelon 1 (ipsilateral hilum), 2 (ipsilateral station 4 and 7), and 3 (rest of the mediastinum, contralateral hilum). The endpoints were overall survival (OS), progression-free survival (PFS), and freedom from local progression (FFLP).

Results

The median follow-up time (95 % confidence interval [CI]) was 41.1 (33.8 − 50.4) months. Patients with a high absolute number of PET-positive LN stations had worse OS (hazard ratio [HR] = 1.09; 95 % CI 0.99 − 1.18; p = 0.05) and PFS (HR = 1.12; 95 % CI 1.04 − 1.20; p = 0.003), irrespective of treatment arm allocation. The prescribed RT dose to the LNs did not correlate with any of the endpoints when considering all patients. However, in patients in arm B (i.e., PET-based selective nodal irradiation), prescribed RT dose to each LN station correlated significantly with FFLP (HR=0.45; 95 % CI 0.24–0.85; p = 0.01). Furthermore, patients with involvement of echelon 3 LN stations had worse PFS (HR = 2.22; 95 % CI 1.16–4.28; p = 0.02), also irrespective of allocation.

Conclusion

Mediastinal tumor burden and lymphatic involvement patterns influence outcome in patients treated with definitive chemoradiotherapy for locally advanced NSCLC. Higher dose to LNs did not improve OS, but did improve FFLP in patients treated with PET-based dose-escalated RT.