Modern radiotherapy techniques enable delivery of high doses to the target volume without escalating dose to organs at risk, offering the possibility of better local control while preserving good ...quality of life. Uncertainties in target volume delineation have been demonstrated for most tumour sites, and various studies indicate that inconsistencies in target volume delineation may be larger than errors in all other steps of the treatment planning and delivery process. The aim of this paper is to summarize the degree of delineation uncertainties for different tumour sites reported in the literature and review the effect of strategies to minimize them.
Our review confirmed that interobserver variability in target volume contouring represents the largest uncertainty in the process for most tumour sites, potentially resulting in a systematic error in dose delivery, which could influence local control in individual patients. For most tumour sites the optimal combination of imaging modalities for target delineation still needs to be determined. Strict use of delineation guidelines and protocols is advisable both in every day clinical practice and in clinical studies to diminish interobserver variability. Continuing medical education of radiation oncologists cannot be overemphasized, intensive formal training on interpretation of sectional imaging should be included in the program for radiation oncology residents.
The concept of the use of MRI for image-guided adaptive brachytherapy (IGABT) in locally advanced cervical cancer was introduced 20 years ago. Here, we report on EMBRACE-I, which aimed to evaluate ...local tumour control and morbidity after chemoradiotherapy and MRI-based IGABT.
EMBRACE-I was a prospective, observational, multicentre cohort study. Data from patients from 24 centres in Europe, Asia, and North America were prospectively collected. The inclusion criteria were patients older than 18 years, with biopsy-proven squamous cell carcinoma, adenocarcinoma, or adenosquamous carcinoma of the uterine cervix, The International Federation of Gynecology and Obstetrics (FIGO) stage IB–IVA disease or FIGO stage IVB disease restricted to paraaortic lymph metastasis below the L1–L2 interspace, suitable for curative treatment. Treatment consisted of chemoradiotherapy (weekly intravenous cisplatin 40 mg/m2, 5–6 cycles, 1 day per cycle, plus 45–50 Gy external-beam radiotherapy delivered in 1·8–2 Gy fractions) followed by MRI-based IGABT. The MRI-based IGABT target volume definition and dose reporting was according to Groupe Européen de Curiethérapie European Society for Radiation Oncology recommendations. IGABT dose prescription was open according to institutional practice. Local control and late morbidity were selected as primary endpoints in all patients available for analysis. The study was registered with ClinicalTrials.gov, NCT00920920.
Patient accrual began on July 30, 2008, and closed on Dec 29, 2015. A total of 1416 patients were registered in the database. After exclusion for not meeting patient selection criteria before treatment, being registered but not entered in the database, meeting the exclusion criteria, and being falsely excluded, data from 1341 patients were available for analysis of disease and data from 1251 patients were available for assessment of morbidity outcome. MRI-based IGABT including dose optimisation was done in 1317 (98·2%) of 1341 patients. Median high-risk clinical target volume was 28 cm3 (IQR 20–40) and median minimal dose to 90% of the clinical target volume (D90%) was 90 Gy (IQR 85–94) equi-effective dose in 2 Gy per fraction. At a median follow-up of 51 months (IQR 20–64), actuarial overall 5-year local control was 92% (95% CI 90–93). Actuarial cumulative 5-year incidence of grade 3–5 morbidity was 6·8% (95% CI 5·4–8·6) for genitourinary events, 8·5% (6·9–10·6) for gastrointestinal events, 5·7% (4·3–7·6) for vaginal events, and 3·2% (2·2–4·5) for fistulae.
Chemoradiotherapy and MRI-based IGABT result in effective and stable long-term local control across all stages of locally advanced cervical cancer, with a limited severe morbidity per organ. These results represent a positive breakthrough in the treatment of locally advanced cervical cancer, which might be used as a benchmark for clinical practice and all future studies.
Medical University of Vienna, Aarhus University Hospital, Elekta AB, and Varian Medical Systems.
Abstract Purpose Image guided brachytherapy (IGBT) for locally advanced cervical cancer allows dose escalation to the high-risk clinical target volume (HRCTV) while sparing organs at risk (OAR). This ...is the first comprehensive report on clinical outcome in a large multi-institutional cohort. Patients and methods From twelve centres 731 patients, treated with definitive EBRT ± concurrent chemotherapy followed by IGBT, were analysed. Kaplan–Meier estimates at 3/5 years were calculated for local control (LC, primary endpoint), pelvic control (PC), overall survival (OS), cancer specific survival (CSS). In 610 patients, G3–4 late toxicity (CTCAEv3.0) was reported. Results Median follow up was 43 months, percent of patients per FIGO stage IA/IB/IIA 22.8%, IIB 50.4%, IIIA–IVB 26.8%. 84.8% had squamous cell carcinomas; 40.5% lymph node involvement. Mean EBRT dose was 46 ± 2.5 Gy; 77.4% received concurrent chemotherapy. Mean D90 HRCTV was 87 ± 15 Gy (EQD210 ), mean D2cc was: bladder 81 ± 22 Gy, rectum 64 ± 9 Gy, sigmoid 66 ± 10 Gy and bowel 64 ± 9 Gy (all EQD23 ). The 3/5-year actuarial LC, PC, CSS, OS were 91%/89%, 87%/84%, 79%/73%, 74%/65%. Actuarial LC at 3/5 years for IB, IIB, IIIB was 98%/98%, 93%/91%, 79%/75%. Actuarial PC at 3/5 years for IB, IIB, IIIB was 96%/96%, 89%/87%, 73%/67%. Actuarial 5-year G3–G5 morbidity was 5%, 7%, 5% for bladder, gastrointestinal tract, vagina. Conclusion IGBT combined with radio-chemotherapy leads to excellent LC (91%), PC (87%), OS (74%), CSS (79%) with limited severe morbidity.
Abstract Background and purpose Currently, there is no consensus on dose prescription in image guided adaptive brachytherapy (IGABT) in locally advanced cervical cancer. The purpose of this study was ...to provide evidence based recommendations for tumor dose prescription based on results from a multi-center patient series (retroEMBRACE). Materials and methods This study analyzed 488 locally advanced cervical cancer patients treated with external beam radiotherapy ± chemotherapy combined with IGABT. Brachytherapy contouring and reporting was according to ICRU/GEC-ESTRO recommendations. The Cox Proportional Hazards model was applied to analyze the effect on local control of dose-volume metrics as well as overall treatment time (OTT), dose rate, chemotherapy, and tumor histology. Results With a median follow up of 46 months, 43 local failures were observed. Dose (D90) to the High Risk Clinical Target Volume (CTVHR ) ( p = 0.022, HR = 0.967 per Gy) was significant for local control, whereas increasing CTVHR volume ( p = 0.004, HR = 1.017 per cm3 ), and longer OTT ( p = 0.004, HR = 1.023 per day) were associated with worse local control. Histology ( p = 0.084), chemotherapy ( p = 0.49) and dose rate ( p = 1.00) did not have significant impact on local control. Separate analyses according to stage of disease showed that dose to CTVHR , residual gross tumor volume (GTVres ), and Intermediate Risk CTV (CTVIR ) has significant impact on local control. Conclusion CTVHR dose of ⩾85 Gy (D90) delivered in 7 weeks provides 3-year local control rates of >94% in limited size CTVHR (20 cm3 ), >93% in intermediate size (30 cm3 ) and >86% in large size (70 cm3 ) CTVHR . CTVIR and GTVres dose of ⩾60 Gy and ⩾95 Gy (D98) leads to similar local control. A dose of 5 Gy (CTVHR ) is required to compensate an increase of OTT by one week. Increased CTVHR volume by 10 cm3 requires additional 5 Gy for equivalent local control.
•CT Based Contouring recommendations in IGABT for cervical cancer is a collaborative effort of 13 experts from Indian Brachytherapy Society (IBS), GEC-ESTRO and American Brachytherapy Society ...(ABS).•The recommendations are comprehensive, providing a pragmatic solution to contour target on CT Imaging at BT in different prevailing clinic-radiological environments which have not been comprehensively addressed.•We expect each institution with no access to MRI at BT to review their working environment and utilize appropriate definitions for defining the target to implement CT based IGABT for cervical cancers.
MR Imaging is regarded asthe gold standardfor Image Gudied Adaptive Brachytherapy (IGABT) for cervical cancer. However, its wide applicability is limited by its availability, logistics and financial implications. Use of alternative imaging like CTand Ultrasound (US) for IGABT has been attempted. In order to arrive at a systematic, uniform and international approach for CT based definition and contouring of target structures, GEC ESTRO, IBS and ABS agreed to jointly develop such recommendations based on the concepts and terms as published in the ICRU Report 89.
The minimum requirements are clinical examination & documentation, CT or MR imaging at diagnosis and at a minimum, CT imaging with the applicator in place. The recommendations are based on (i) assessment of the GTV at diagnosis and at brachytherapy, (ii) categorizing the response to external radiation into different clinical remission patterns, (iii) defining various clinico-radiological environments and (iv) definition & delineation of a target on CT imaging at the time of brachytherapy with the applicator in situ. CT based target contouring recommendations based on 4 remission categories within 8 defined environments, aim at improving the contouring accuracy for IGABT using CT, US and MRI as available. For each clinico-radiological environment, there is an attempt to minimize the specific uncertainties in order to arrive at the best possible contouring accuracy.
Evaluating feasibility & reproducibility, to achieve a benchmark towards a gold standard MR IGABT and further clinical research including outcomes with CT Based IGABT will become the next steps.
Image guided adaptive brachytherapy (IGABT) for cervical cancer improves pelvic control and survival across all stages. Improvement in pelvic control is larger in advanced stages, but improvement in ...survival is similar across stages. This paper analyzes the patterns of failure in the RetroEMBRACE cohort to investigate this discrepancy.
731 patients from 12 institutions treated with chemoradiation therapy and magnetic resonance imaging or computed tomography-based IGABT were evaluated. The pattern of failure at time of first relapse was analyzed.
Three hundred twenty-five failures (single and synchronous) occurred in 222 of 731 patients (30%). Among the 325 failures, 9% were local and 6% regional. Pelvic (local or regional) failures made up 13%, paraaortic node (PAN) 9%, systemic 21%, and distant (systemic + PAN) 24%. Of the 222 patients with treatment failure, 21% had pelvic failure alone, 57% had distant failure alone, and 23% had both pelvic and distant failure. Of all failures that occurred, 40% to 50% occurred in the first year, with a further 20% to 30% occurring in the second year. Although local, regional, and PAN failure tended to plateau after year 3, systemic failure continued to occur up to year 10.
Implementation of IGABT has changed the patterns of relapse after chemoradiation therapy for cervical cancer. The predominant failure after IGABT is systemic, whereas the predominant failure with conventional brachytherapy is pelvic. Effective treatments to eradicate micrometastases in PAN and distant organs are needed in addition to IGABT and chemoradiation therapy to maximize local, regional, PAN, and systemic control and improve survival.
To create and compare consensus clinical target volume (CTV) contours for computed tomography (CT) and 3-Tesla (3-T) magnetic resonance (MR) image-based cervical-cancer brachytherapy.
Twenty-three ...experts in gynecologic radiation oncology contoured the same 3 cervical cancer brachytherapy cases: 1 stage IIB near-complete response (CR) case with a tandem and ovoid, 1 stage IIB partial response (PR) case with tandem and ovoid with needles, and 1 stage IB2 CR case with a tandem and ring applicator. The CT contours were completed before the MRI contours. These were analyzed for consistency and clarity of target delineation using an expectation maximization algorithm for simultaneous truth and performance level estimation (STAPLE), with κ statistics as a measure of agreement between participants. The conformity index was calculated for each of the 6 data sets. Dice coefficients were generated to compare the CT and MR contours of the same case.
For all 3 cases, the mean tumor volume was smaller on MR than on CT (P<.001). The κ and conformity index estimates were slightly higher for CT, indicating a higher level of agreement on CT. The Dice coefficients were 89% for the stage IB2 case with a CR, 74% for the stage IIB case with a PR, and 57% for the stage IIB case with a CR.
In a comparison of MR-contoured with CT-contoured CTV volumes, the higher level of agreement on CT may be due to the more distinct contrast medium visible on the images at the time of brachytherapy. MR at the time of brachytherapy may be of greatest benefit in patients with large tumors with parametrial extension that have a partial or complete response to external beam. On the basis of these results, a 95% consensus volume was generated for CT and for MR. Online contouring atlases are available for instruction at http://www.nrgoncology.org/Resources/ContouringAtlases/GYNCervicalBrachytherapy.aspx.
Abstract Objective To develop a method for the assessment and characterization of 3D geometric distortion as part of routine quality assurance for MRI scanners commissioned for Radiation Therapy ...planning. Materials and Methods In this study, the in-plane and through-plane geometric distortion on a 1.5T GE MRI-SIM unit are characterized and the 2D and 3D correction algorithms provided by the vendor are evaluated. We used a phantom developed by GE Healthcare that covers a large field of view of 500mm, and consists of layers of foam embedded with a matrix of ellipsoidal markers. An in-house Java-based software module was developed to automatically assess the geometric distortion by calculating the center of each marker using the center of mass method, correcting of gross rotation errors and comparing the corrected positions with a CT gold standard data set. Spatial accuracy of typical pulse sequences used in RT planning was assessed (2D T1/T2 FSE, 3D CUBE, T1 SPGR) using the software. The accuracy of vendor specific geometric distortion correction (GDC) algorithms was quantified by measuring distortions before and after the application of the 2D and 3D correction algorithms. Results Our algorithm was able to accurately calculate geometric distortion with sub-pixel precision. For all typical MR sequences used in Radiotherapy, the vendors GDC were able to substantially reduce the distortions. Our results showed also that the impact of the acquisition produced a maximum variation of 0.2mm over a radial distance of 200mm. It has been shown that while the 2D correction algorithm remarkably reduces the in-plane geometric distortion, 3D geometric distortion further reduced the geometric distortion by correcting both in-plane and through-palne distortion in all acquisitions. Conclusion The presented methods represent a valuable tool for routine quality assurance of MR applications that require stringent spatial accuracy assessment such as radiotherapy. The phantom used in this study provides three dimensional arrays of control points. These tools and the detailed results can be also used for developing new geometric distortion correction algorithms or improving the existing ones.
The aims of this study were to investigate the clinical feasibility and to report on preliminary treatment outcomes of combined intracavitary/interstitial brachytherapy, using a novel applicator and ...magnetic resonance imaging (MRI)-based treatment planning in patients with locally advanced cervical cancer.
A total of 22 cervical cancer patients with insufficient response and/or unfavorable topography after external-beam irradiation were included in this study. Parametrial extent of the disease in these patients was judged to exceed the coverage limit of intracavitary brachytherapy alone. A modified tandem/ring (T/R) applicator for guidance of parametrial needles (N) was used to perform high-dose-rate-brachytherapy with MRI-based treatment planning. Clinical feasibility and preliminary treatment outcomes were assessed.
A total of 44 interstitial needle implants were performed. The spatial relations between the T/R + N applicator, high-risk clinical target volume, and organs at risk were visible clearly in all cases. Accurate and reproducible needle placement could be achieved in the majority of cases. No severe adverse events were caused by the intervention. The mean follow-up period was 20 months (range, 5-35 months). No G3 to G4 early or persistent late side effects were observed. Complete remission was achieved in 21 patients (95%). One local recurrence was observed within the high-risk clinical target volume area during follow-up.
Our preliminary clinical experience indicates that combined intracavitary and interstitial MRI-based brachytherapy in patients with significant residual disease after external-beam therapy extending up to the distal third of parametria is feasible and allows excellent local control and a low rate of morbidity.
Abstract Background and purpose To investigate the inter-observer variation of target contouring when using the GYN GEC-ESTRO recommendations for MR image-guided brachytherapy (IGBT) for cervical ...cancer. Materials and methods Nineteen cervical cancer patients, treated by radiotherapy at the Institut Gustave Roussy (IGR) in France ( n = 9) or at the Medical University of Vienna (AKH) in Austria ( n = 10) were included in this study. IGBT was used for all patients. Two radiation oncologists, one from IGR and the other from AKH, outlined the target volumes on MRI at the time of brachytherapy according to the GYN GEC-ESTRO recommendations. The absolute, common and encompassing volumes and their conformity indices (CIs) were assessed for the GTV, HR CTV and IR CTV. D90 and D100 for each volume were assessed. Visual evaluation was made to assess the reasons for the most frequent inter-observer differences. Results The mean volumes of GTV and HR CTV did not differ significantly between the observers, p > 0.05. Significant differences were observed only for the mean volumes of the IR CTV of both centres, p < 0.05. CIs ranged from 0.5 to 0.7. DVH-parameter analyses did not reveal any statistical differences, except for the D100 for the GTV at AKH, and the D90 for the IR CTV at IGR, p < 0.05. Underlying reasons for inter-observer differences included image contrast adjustment and neglecting to consider anatomical borders. Conclusions The results of this inter-observer study show that the application of the GYN GEC-ESTRO recommendations for IGBT contouring at two different institutions with two different traditions for applicators, CTV assessment, MR image acquisition and dose prescription is feasible, and it produces acceptable inter-observer variability.
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