Adaptive Radiotherapy for Carcinoma of the Urinary Bladder: Long-term Outcomes With Dose Escalation

Is trimodal therapy the current standard for muscle-invasive bladder cancer?

OBJECTIVE

The aim of this review is to summarize the current evidence and future perspectives of bladder-sparing treatment for MIBC.

METHODS

A non-systematic literature search in Medline/Pubmed was performed in October 2023 with the following keywords "bladder cancer", "bladder-sparing", "trimodal therapy", "chemoradiation", "biomarkers", "immunotherapy", "neoadjuvant chemotherapy", "radiotherapy".

RESULTS

Urology guidelines recommend radical cystectomy as the standard curative treatment for muscle-invasive urothelial bladder cancer, reserving radiotherapy for patients who are unfit or who want to preserve their bladder. Given the morbidity and mortality of cystectomy and its impact on quality of life and bladder function, modern oncologic therapies are increasingly oriented toward organ preservation and maximizing functional outcomes while maintaining treatment efficacy. Trimodal therapy, which incorporates maximal transurethral resection followed by radiotherapy with concurrent radiosensitizing chemotherapy, is an effective regimen for bladder function preservation in well-selected patients. Despite the absence of comparative data from randomized trials, the two approaches seem to provide comparable oncologic outcomes. Studies are evaluating the expansion of eligibility criteria for trimodal therapy, the optimization of radiotherapy and immunotherapy delivery to further improve outcomes, and the validation of biomarkers to guide bladder preservation.

CONCLUSIONS

Trimodal therapy has shown acceptable outcomes for bladder preservation; therefore, it provides a valid treatment option in well-selected patients.

The role of radiation therapy for de novo metastatic bladder and renal cancers

Metastatic bladder and renal cancers account respectively for 2.1% and 1.8% of cancer deaths worldwide. The advent of immune checkpoint inhibitors has revolutionized the management of metastatic disease, by demonstrating considerable improvements in overall survival. However, despite initial sensitivity to immune checkpoint inhibitors for most patients, both bladder and renal cancer are associated with short progression-free survival and overall survival, raising the need for further strategies to improve their efficacy. Combining systemic therapies with local approaches is a longstanding concept in urological oncology, in clinical settings including both oligometastatic and polymetastatic disease. Radiation therapy has been increasingly studied with either cytoreductive, consolidative, ablative or immune boosting purposes, but the long-term impact of this strategy remains unclear. This review intends to address the impact of radiation therapy with either curative or palliative intent, for synchronous de novo metastatic bladder and renal cancers.

Dose-Escalated Radiation Therapy as Primary Treatment for Residual Bladder Cancer After Transurethral Resection

Purpose

The aim of this study was to determine whether escalating the local radiation dose can improve the outcome of residual bladder cancer after transurethral resection of bladder tumor without increasing treatment-related toxicity.

Methods and Materials

The treatment plans and medical records of patients with bladder cancer treated with curative-intent radiation therapy between 2008 and 2020 were reviewed. Those who had residual tumors in the computed tomography simulation images were included. A cumulative radiation dose higher than 6600 cGy was defined as dose escalation. The effect of dose escalation on 3-year locoregional control, progression-free survival, and overall survival was evaluated.

Results

A total of 149 patients with residual tumors were identified. The median follow-up period was 27.5 months. Among them, 51 patients received an escalated radiation dose, and 98 received a standard dose in the residual tumor area. Patients in the dose-escalation group had higher 3-year locoregional control (65.6% vs 27.8%; P < .001) and progression-free survival (42.6% vs 18.2%; P < .001) than the standard-dose group. Overall survival also showed a trend favoring the dose-escalation group (54.9% vs 36.2%; P = .059). In the multivariate analyses, the differences between the dose-escalation and standard-dose groups were significant in terms of locoregional control (hazard ratio, 0.32; CI, 0.18-0.59; P = <.001) and progression-free survival (hazard ratio, 0.51; CI, 0.32-0.82; P = .005). There was no statistical difference in acute and chronic treatment-related toxicities between the 2 groups.

Conclusions

The outcome of residual bladder cancer after transurethral resection of bladder tumor could be improved by dose-escalated radiation therapy.

Utilising alternative cystoscopic schedules to minimise cost and patient burden after trimodality therapy for muscle-invasive bladder cancer

BACKGROUND

To assess urinary symptoms and urine cytology as screening tools for cystoscopic detection of local recurrence after bladder-preserving trimodality treatment (TMT).

METHODS

Patients with muscle-invasive bladder cancer receiving definitive TMT follow-up three monthly for 2 years, six monthly for the next 3 years and then yearly, with a clinical review, urine cytology and cystoscopy at each visit (triple assessment, TA). Grade 2+ cystitis/haematuria absent/present was scored 0/1, and urine cytology reported negative/suspicious or positive was scored 0/1, respectively. The performance of these two parameters for predicting local recurrence in cystoscopic biopsy was tested. Other hypothetical surveillance schedules included cystoscopy on alternate visits (COAV), or suspected recurrence (COSR), six-monthly COSR and six-monthly TA.

RESULTS

A total of 630 follow-up visits in 112 patients with 19 recurrences (7 muscle invasive, 12 non-muscle invasive) at a median follow-up of 19 months were analysed. The sensitivity and specificity of clinical symptoms were 47.4% and 92%, and for urine cytology 58% and 85%, respectively. The combination of clinical symptoms and cytology (COSR) was 95% sensitive and 78% specific for local recurrence but 100% sensitive for muscle-invasive recurrence. Both COAV and COSV schedules showed a high area under the curve (AUC) for detecting local recurrence (COAV = 0.84, COSR = 0.83), muscle-invasive recurrence (AUC = 0.848 each) and non-muscle-invasive recurrence (COAV = 0.82, COSR = 0.81); reducing the need for TAs by 64% and 67% respectively, and overall cost by 18% and 33%, respectively.

CONCLUSION

Cystoscopy at suspected recurrence during follow-up is safe and the most cost-effective for detecting muscle-invasive local recurrences, while cystoscopy at alternate visits may be more optimal for detecting any local recurrence.

Mapping Local Failure Following Bladder Radiotherapy According to Dose

AIMS

To determine the relationship between local relapse following radical radiotherapy for muscle-invasive bladder cancer (MIBC) and radiation dose.

MATERIALS AND METHODS

Patients with T2-4N0-3M0 MIBC were recruited to a phase II study assessing the feasibility of intensity-modulated radiotherapy to the bladder and pelvic lymph nodes. Patients were planned to receive 64 Gy/32 fractions to the bladder tumour, 60 Gy/32 fractions to the involved pelvic nodes and 52 Gy/32 fractions to the uninvolved bladder and pelvic nodes. Pre-treatment set-up was informed by cone-beam CT. For patients who experienced local relapse, cystoscopy and imaging (CT/MRI) was used to reconstruct the relapse gross tumour volume (GTVrelapse) on the original planning CT . GTVrelapse D98% and D95% was determined by co-registering the relapse image to the planning CT utilising deformable image registration (DIR) and rigid image registration (RIR). Failure was classified into five types based on spatial and dosimetric criteria as follows: A (central high-dose failure), B (peripheral high-dose failure), C (central elective dose failure), D (peripheral elective dose failure) and E (extraneous dose failure).

RESULTS

Between June 2009 and November 2012, 38 patients were recruited. Following treatment, 18/38 (47%) patients experienced local relapse within the bladder. The median time to local relapse was 9.0 months (95% confidence interval 6.3-11.7). Seventeen of 18 patients were evaluable based on the availability of cross-sectional relapse imaging. A significant difference between DIR and RIR methods was seen. With the DIR approach, the median GTVrelapse D98% and D95% was 97% and 98% of prescribed dose, respectively. Eleven of 17 (65%) patients experienced type A failure and 6/17 (35%) patients type B failure. No patients had type C, D or E failure. MIBC failure occurred in 10/17 (59%) relapsed patients; of those, 7/11 (64%) had type A failure and 3/6 (50%) had type B failure. Non-MIBC failure occurred in 7/17 (41%) patients; 4/11 (36%) with type A failure and 3/6 (50%) with type B failure.

CONCLUSION

Relapse following radiotherapy occurred within close proximity to the original bladder tumour volume and within the planned high-dose region, suggesting possible biological causes for failure. We advise caution when considering margin reduction for future reduced high-dose radiation volume or partial bladder radiotherapy protocols.

Role of radiotherapy in the management of bladder cancer: Recommendations of the French society for radiation oncology

We present the recommendations of the French society of oncological radiotherapy on the indications and techniques for external beam radiotherapy for bladder cancer.

A practical approach to bladder preservation with hypofractionated radiotherapy for localised muscle-invasive bladder cancer

Bladder preservation with trimodality treatment (TMT) is an alternative strategy to radical cystectomy (RC) for the management of localised muscle invasive bladder cancer (MIBC). TMT comprises of transurethral resection of the bladder tumour (TURBT) followed by radiotherapy with concurrent radiosensitisation. TMT studies have shown neo-adjuvant chemotherapy with cisplatin-based regimens is often given to further improve survival outcomes. A hypofractionated radiotherapy regimen is preferable due to its non-inferiority in local control and late toxicities. Radiosensitisation can comprise concurrent chemotherapy (with gemcitabine, cisplatin or combination fluorouracil and mitomycin), CON (carbogen and nicotinomide) or hyperthermic treatment. Radiotherapy techniques are continuously improving and becoming more personalised. As the bladder is a mobile structure subject to volumetric changes from filling, an adaptive approach can optimise bladder coverage and reduce dose to normal tissue. Adaptive radiotherapy (ART) is an evolving field that aims to overcome this. Improved knowledge of tumour biology and advances in imaging techniques aims to further optimise and personalise treatment.

A retrospective review of the long-term outcomes of online adaptive radiation therapy and conventional radiation therapy for muscle invasive bladder cancer

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Risks with tight adaptive RT margins.

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Cancer control may be poorer if margins tight.

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Prospective studies required.

Background and Purpose

To report long-term outcomes of online image-guided (IG) adaptive radiation therapy (aRT) versus conventional IG radiation therapy (cRT) for bladder preservation in muscle-invasive bladder cancer (MIBC).

Materials and Methods

A retrospective review of patients with histologically proven MIBC who were prescribed radical intent radiation therapy (RT) following trans-urethral resection of bladder tumour (TURBT) was conducted. There were three groups based on their RT treatment modality: conventional RT (cRT), margin 5 mm adaptive RT (aRT5mm) and margin 7 mm adaptive RT (aRT7mm).

Results

171 patients were included in this study, with median age of 79.4 years (41–90). Approximately half of all patients received concurrent chemotherapy. N = 57 underwent cRT, n = 39 underwent aRT5mm, and n = 75 underwent aRT7mm. Response evaluable patients in all three groups (n = 133) had high rates of complete response (CR, 83%) on first post-RT cystoscopy with no significant differences between the groups. At a median follow-up of 54 months, the 5-year freedom from muscle-invasive failure survival (FFMIFS) in the cRT, aRT5mm, and aRT7mm groups were 75%, 59%, and 98%, respectively. The estimated cancer specific survival (CSS) at 5 years were 60%, 30%, and 59%, respectively. The estimated overall survival (OS) at 5 years were 43%, 26%, and 38%, respectively. The incidence of late grade 3 or 4 toxicity was n = 5 in aRT5mm, n = 2 in cRT group, and n = 1 in aRT7mm.

Conclusion

IG aRT with 7 mm expansion for MIBC provides higher rates of FFMIFS, similar 5-year CSS and OS, as well as toxicity outcomes when compared to cRT. aRT with 5 mm expansion with this RT protocol is not recommended for treatment.

Recommendations for planning and delivery of radical radiotherapy for localized urothelial carcinoma of the bladder

PURPOSE

Curative radio-chemotherapy is recognized as a standard treatment option for muscle-invasive bladder cancer (MIBC). Nevertheless, the technical aspects for MIBC radiotherapy are heterogeneous with a lack of practical recommendations.

METHODS AND MATERIALS

In 2018, a workshop identified the need for two cooperative groups to develop consistent, evidence-based guidelines for irradiation technique in the delivery of curative radiotherapy. Two radiation oncologists performed a review of the literature addressing several topics relative to radical bladder radiotherapy: planning computed tomography acquisition, target volume delineation, radiation schedules (total dose and fractionation) and dose delivery (including radiotherapy techniques, image-guided radiotherapy (IGRT) and adaptive treatment modalities). Searches for original and review articles in the PubMed and Google Scholar databases were conducted from January 1990 until March 2020. During a meeting conducted in October 2020, results on 32 topics were presented and discussed with a working group involving 15 radiation oncologists, 3 urologists and one medical oncologist. We applied the American Urological Association guideline development's method to define a consensus strategy.

RESULTS

A consensus was obtained for all 34 except 4 items. The group did not obtain an agreement on CT enhancement added value for planning, PTV margins definition for empty bladder and full bladder protocols, and for pelvic lymph-nodes irradiation. High quality evidence was shown in 6 items; 8 items were considered as low quality of evidence.

CONCLUSION

The current recommendations propose a homogenized modality of treatment both for routine clinical practice and for future clinical trials, following the best evidence to date, analyzed with a robust methodology. The XXX group formulates practical guidelines for the implementation of innovative techniques such as adaptive radiotherapy.

Image-guided Adaptive Radiotherapy for Bladder Cancer

Technological advancement has facilitated patient-specific radiotherapy in bladder cancer. This has been made possible by developments in image-guided radiotherapy (IGRT). Particularly transformative has been the integration of volumetric imaging into the workflow. The ability to visualise the bladder target using cone beam computed tomography and magnetic resonance imaging initially assisted with determining the magnitude of inter- and intra-fraction target change. It has led to greater confidence in ascertaining true anatomy at each fraction. The increased certainty of dose delivered to the bladder has permitted the safe reduction of planning target volume margins. IGRT has therefore improved target coverage with a reduction in integral dose to the surrounding tissue. Use of IGRT to feed back into plan and dose delivery optimisation according to the anatomy of the day has enabled adaptive radiotherapy bladder solutions. Here we undertake a review of the stepwise developments underpinning IGRT and adaptive radiotherapy strategies for external beam bladder cancer radiotherapy. We present the evidence in accordance with the framework for systematic clinical evaluation of technical innovations in radiation oncology (R-IDEAL).

Will the Use of Biomarkers Improve Bladder Cancer Radiotherapy Delivery?

Advances in the field of cancer biology and molecular techniques have led to a better understanding of the molecular underpinnings driving cancer development and outcomes. Simultaneously, advances in imaging have allowed for improved sensitivity in initial staging, radiotherapy planning and follow-up of numerous cancers. These two phenomena have led to the development of biomarkers that can guide therapy in multiple malignancies. In bladder cancer, there is extensive ongoing research into the identification of biomarkers that can help tailor personalised approaches for treatment based on the intrinsic tumour biology. However, the delivery of bladder cancer radiotherapy as part of trimodality therapy currently has a paucity of biomarkers to guide treatment. Here we summarise the existing literature and ongoing investigations into potential predictive and prognostic molecular and imaging biomarkers that may one day guide selection for utilisation of radiotherapy as part of trimodality therapy, guide selection of the radiosensitising agent, guide radiation dose and target, and guide surveillance for recurrence after trimodality therapy.

MR-Guided Adaptive Radiotherapy for Bladder Cancer

Radiotherapy has an important role in the curative and palliative treatment settings for bladder cancer. As a target for radiotherapy the bladder presents a number of technical challenges. These include poor tumor visualization and the variability in bladder size and position both between and during treatment delivery. Evidence favors the use of magnetic resonance imaging (MRI) as an important means of tumor visualization and local staging. The availability of hybrid systems incorporating both MRI scanning capabilities with the linear accelerator (MR-Linac) offers opportunity for in-room and real-time MRI scanning with ability of plan adaption at each fraction while the patient is on the treatment couch. This has a number of potential advantages for bladder cancer patients. In this article, we examine the technical challenges of bladder radiotherapy and explore how magnetic resonance (MR) guided radiotherapy (MRgRT) could be leveraged with the aim of improving bladder cancer patient outcomes. However, before routine clinical implementation robust evidence base to establish whether MRgRT translates into improved patient outcomes should be ascertained.

[A review of adaptive radiotherapy for bladder cancer]

PURPOSE

Radiation therapy (RT) for muscle invasive bladder cancer (MIBC) is challenging, with observed variations in bladder shape and size resulting in inappropriate coverage of the target volumes (CTV). Large margins were historically applied around the CTV, increasing the dose delivered to organs at risk (OAR). With repositioning imaging and visualization of soft tissues during image guided RT, an opportunity to consider these movements and deformations appeared possible with an adaptive RT approach (ART).

MATERIALS AND METHODS

A bibliographic search on the PubMed database has been done in January 2019. Studies focusing on patients with MIBC, treating on ART, with the objectives of feasibility, clinical and/or dosimetric evaluation and comparison with a standard irradiation technique were eligible. The purpose of this review was to define the different ART techniques used in clinical practice, to discuss their advantages compared to conventional RT in terms of target volume's coverage and OAR dose and to describe their feasibility in clinical practice.

RESULTS

A total of 30 studies were selected. The strategies known as "composite offline", "plan of the day" not individualized or individualized, and "re-optimization" have been identified. All the studies have shown a significant benefit of ART in target coverage and dose of OAR, especially the rectum and small bowel. All ART plans produced are not used during RT sessions. Inter-observer variability for the selection of these plans can be observed. The practical implementation within a department required staff education and training, and increases the duration of treatment preparation. The "A-POLO" approach seems to be the most suitable for practice.

CONCLUSION

ART is the technique of choice for bladder cancer RT. The "plan of the day" approach, individualized according to the A-POLO methodology, seems to be the most effective. The emergence of daily re-optimization, especially using MRI-Linac, is promising. The correlation between dosimetric benefits and clinical efficacy and safety results should be demonstrated into future trials.

Current Status of Anatomical Magnetic Resonance Imaging in Brachytherapy and External Beam Radiotherapy Planning and Delivery

Radiotherapy planning and delivery have dramatically improved in recent times. Imaging is key to a successful three-dimensional and increasingly four-dimensional based pathway with computed tomography embedded as the backbone modality. Computed tomography has significant limitations for many tumour sites where soft-tissue discrimination is suboptimal, and where magnetic resonance imaging (MRI) has largely superseded in the diagnostic arena. MRI is increasingly used together with computed tomography in the radiotherapy planning pathway and is now established as a prerequisite for several tumours. With the advent of combined MRI and linear accelerator (MR-linac) systems, a transition to MRI-based radiotherapy planning is becoming reality, with increasing experience and research involving these new platforms. In this overview, we aim to highlight how magnetic resonance-guided imaging has improved radiotherapy, using gynaecological malignancies to illustrate, in both external beam radiotherapy and image-guided brachytherapy, and will assess the early evidence for magnetic resonance-guided radiotherapy using combined MR-linac systems.

Incidence and outcome of salvage cystectomy after bladder sparing therapy for muscle invasive bladder cancer: a systematic review and meta-analysis

Objective

We conducted a systematic review and meta-analysis to assess the available literature regarding the surgical and oncologic outcomes of patients undergoing salvage radical cystectomy (SV-RC) for recurrence or failure of bladder sparing therapy (BST) for muscle-invasive bladder cancer (MIBC).

Methods

We searched MEDLINE (PubMed), EMBASE and Google Scholar databases in May 2020. We included all studies of patients with ≥ cT2N0/xM0 bladder cancer that were eligible for all treatment modalities at the time of treatment decision who underwent BST including radiotherapy (RTX). A meta-analysis was conducted to calculate the pooled rate of several variables associated with an increased need for SV-RC. Study quality and risk of bias were assessed using MINORS criteria.

Results

73 studies comprising 9110 patients were eligible for the meta-analysis. Weighted mean follow-up time was 61.1 months (range 12–144). The pooled rate of non-response to BST and local recurrence after BST, the two primary reasons for SV-RC, was 15.5% and 28.7%, respectively. The pooled rate of SV-RC was 19.2% for studies with a follow-up longer than 5 years. Only three studies provided a thorough report of complication rates after SV-RC. The overall complication rate ranged between 67 and 72% with a 30-day mortality rate of 0–8.8%. The pooled rates of 5 and 10-year disease-free survival after SV-RC were 54.3% and 45.6%, respectively.

Conclusion

Approximately one-fifth of patients treated with BST with a curative intent eventually require SV-RC. This procedure carries a proportionally high rate of complications and is usually accompanied by an incontinent urinary diversion.

Electronic supplementary material

The online version of this article (10.1007/s00345-020-03436-0) contains supplementary material, which is available to authorized users.

Trimodality Therapy for Muscle-Invasive Bladder Cancer: Recent Advances and Unanswered Questions

PURPOSE OF REVIEW

Bladder-sparing trimodality therapy (TMT) has become an accepted alternative to cystectomy for selected muscle invasive bladder cancer (MIBC) patients unfit for cystectomy or opting for bladder preservation. This review will summarize recent advances in TMT for MIBC.

RECENT FINDINGS

A growing body of literature has emerged which supports the use of TMT. However, its delivery is yet to be standardized. The role of chemotherapy and predictive biomarkers remain to be elucidated. Novel bladder-sparing approaches, drug combinations including immunotherapy and targeted therapies are under investigation in clinical trials, with the goal of ultimately enhancing survival and quality of life outcomes. Recent advances in TMT have made bladder preservation possible for MIBC patients seeking an alternative local therapy to cystectomy. With careful patient selection, TMT offers comparable survival outcomes to cystectomy, and improved quality of life as patients are able to successfully retain their bladder.