Stereotactic Body Radiation Therapy in the Management of Oligometastatic and Oligoprogressive Bladder Cancer and Other Urothelial Malignancies

Management of Oligometastatic and Locally Recurrent Urothelial Carcinoma

PURPOSE OF REVIEW

To summarize and evaluate the literature on treatment approaches for oligometastatic and locally recurrent urothelial cancer.

RECENT FINDINGS

There is no clear definition for oligometastatic urothelial cancers due to limited data. Studies focusing on oligometastatic and locally recurrent urothelial cancer have been primarily retrospective. Treatment options include local therapy with surgery or radiation, and generalized systemic therapy such as chemotherapy or immunotherapy. Oligometastatic and locally recurrent urothelial cancers remain challenging to manage, and treatment requires an interdisciplinary approach. Systemic therapy is nearly always a component of current care in the form of chemotherapy, but the role of immunotherapy has not been explored. Consideration of surgical and radiation options may improve outcomes, and no studies have compared directly between the two localized treatment options. The development of new prognostic and predictive biomarkers may also enhance the treatment landscape in the future.

Definitions, outcomes and perspectives for oligometastatic bladder cancer: towards a standardized terminology

PURPOSE OF REVIEW

Oligometastatic (om) cancer is considered as a transitional state in between locally confined disease and widespread metastases, accessible to a multimodal treatment, combining systemic and local therapy. In urothelial bladder cancer (BCa), the definitions and the approaches to this condition are poorly standardised and mainly based on retrospective data. We aim to portray the framework for uro-oncologic terminology in omBCa and go through the latest evidence and the future perspectives.

RECENT FINDINGS

Retrospective and registry data support the potential benefits of multimodality treatment for carefully selected omBCa patients, especially following a good response to systemic treatment. In 2023, a Delphi consensus has defined omBCa, allowing maximum three metastatic lesions, theoretically amenable to radical local treatment. In de-novo omBCa, surgical treatment of primary tumour might improve overall survival (OS), according to a matched registry analysis; also, consolidative radiotherapy was associated with better OS in two recent cohorts. Furthermore, metastasis-directed therapy (MDT) has shown high local control rates and promising OS (14.9-51 months) in a meta-analysis; benefits might be more pronounced for single-site omBCa and nodal or lung lesions.

SUMMARY

From a clinical perspective, in de-novo omBCa, the local treatment of primary and metastatic sites might improve disease control and survival, in selected patients; in the oligorecurrent setting, MDT achieves good local symptom control with limited side effects; in selected cases, it could convey a survival benefit, too. From a research perspective, well designed prospective evidence is eagerly awaited, based on recently adopted shared definitions for omBCa.

Is there a role for metastasis-directed therapy in bladder cancer?

PURPOSE OF REVIEW

This article aims to comprehensively review and critique the existing literature on the role of metastatic-directed therapy in patients with metastatic bladder cancer, particularly in oligometastatic disease state.

RECENT FINDINGS

The role of metastasectomy in metastatic bladder cancer is still controversial. Several studies have demonstrated improved outcomes, particularly in a highly selected patients with small metastatic lesions or with lung or brain metastases, whereas others show no significant survival benefit. Combining metastasectomy with systemic therapies, such as immunotherapy and chemotherapy, has also shown benefits. Metastasis-directed radiotherapy is evolving as a potentially effective approach with minimal toxicity in achieving local control and improving survival, particularly in patients with oligometastatic disease. The evidence regarding the impact of several factors such as performance status, metastatic burden, and the presence of visceral metastases on outcomes is mixed. Concurrent treatment with systemic therapy may potentiate the effectiveness of metastasis-directed therapy.

SUMMARY

In patients with metastatic deposits amenable to surgical resection, metastasectomy stands as a promising avenue. Metastatic-directed radiotherapy has demonstrated local control and improved survival in the evolving landscape of oligometastatic bladder cancer management. Further, well designed multicenter prospective studies are needed to support these findings and better understand the synergy between radiotherapy and systemic treatments, especially immunotherapy.

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.

Radiotherapy in metastatic bladder cancer

PURPOSE

To review available and emerging evidence of radiotherapy for symptom management and disease control in metastatic bladder cancer.

METHODS

A literature search and subsequent cross-referencing were carried out for articles in the PubMed and Scopus databases using terms 'radiotherapy' OR 'palliative radiation therapy' with 'metastatic bladder cancer' OR 'advanced bladder cancer' between 1990 and 2023, excluding articles with no English translation.

RESULTS

Palliative radiotherapy is an effective and accessible treatment for the alleviation of haematuria and pain due to the primary and metastatic disease. With growing recognition of oligometastatic disease state at diagnosis, response, or progression, radiotherapy can consolidate response by ablating residual or resistant lesions. Experience with other primary cancers supports positive impact of radiotherapy on disease control, quality of life, and survival in oligometastatic stage, without significant adverse effects. Alongside immune checkpoint inhibitors, fibroblast growth receptor inhibitors, and antibody-drug conjugates, the immunomodulatory potential of radiotherapy is being explored in combination with these systemic therapies for metastatic bladder cancer.

CONCLUSION

Radiotherapy is an effective, safe, and accessible treatment modality for palliation as well as disease control in various clinical settings of metastatic bladder cancer. Its role in oligometastatic stage in combination with systemic therapy is expected to expand with emerging evidence.

Navigating the Rapidly Evolving Advanced Urothelial Carcinoma Treatment Landscape: Insights from Italian Experts

PURPOSE OF REVIEW

To discuss recent advances in the treatment of advanced urothelial carcinoma (UC) and how best to incorporate new therapies into clinical practice.

RECENT FINDINGS

There have been several recent practice-changing phase 2 and 3 trials of immune checkpoint inhibitors (ICIs), antibody-drug conjugates (ADCs), and targeted agents in advanced UC. Based on data from these trials, ICIs can be used as first-line maintenance therapy in patients who do not progress on platinum-based chemotherapy, second-line therapy for those with progression, and first-line therapy in cisplatin-ineligible patients with PD-L1 expression; ADCs and targeted agents provide later-line treatment options. Despite substantial progress in the treatment of advanced UC, there are still many uncertainties, including the optimal treatment sequence for novel agents, and reliable predictive biomarkers to aid in treatment selection. There is also an unmet need for effective treatment options in patients unfit for any platinum-based chemotherapy.

Definition and Diagnosis of Oligometastatic Bladder Cancer: A Delphi Consensus Study Endorsed by the European Association of Urology, European Society for Radiotherapy and Oncology, and European Society of Medical Oncology Genitourinary Faculty

BACKGROUND

In contrast to other cancers, the concept of oligometastatic disease (OMD) has not been investigated in bladder cancer (BC).

OBJECTIVE

To develop an acceptable definition, classification, and staging recommendations for oligometastatic BC (OMBC) spanning the issues of patient selection and the roles of systemic therapy and ablative local therapy.

DESIGN, SETTING, AND PARTICIPANTS

A European consensus group of 29 experts, led by the European Association of Urology (EAU), the European Society for Radiotherapy and Oncology (ESTRO), and the European Society of Medical Oncology (ESMO), and including members from all other relevant European societies, was established.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A modified Delphi method was used. A systematic review was used to build consensus questions. Consensus statements were extracted from two consecutive surveys. The statements were formulated during two consensus meetings. Agreement levels were measured to determine if consensus was achieved (≥75% agreement).

RESULTS AND LIMITATIONS

The first survey included 14 questions and the second survey had 12. Owing to a considerable lack of evidence, which was the major limitation, definition was limited in the context of de novo OMBC, which was further classified as synchronous OMD, oligorecurrence, and oligoprogression. A maximum of three metastatic sites, all resectable or amenable to stereotactic therapy, was proposed as the definition of OMBC. Pelvic lymph nodes represented the only "organ" not included in the definition of OMBC. For staging, no consensus on the role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography was reached. A favourable response to systemic treatment was proposed as the criterion for selection of patients for metastasis-directed therapy.

CONCLUSIONS

A consensus statement on the definition and staging of OMBC has been formulated. This statement will help to standardise inclusion criteria in future trials, potentiate research on aspects of OMBC for which consensus was not achieved, and hopefully will lead to the development of guidelines on optimal management of OMBC.

PATIENT SUMMARY

As an intermediate state between localised cancer and disease with extensive metastasis, oligometastatic bladder cancer (OMBC) might benefit from a combination of systemic treatment and local therapy. We report the first consensus statements on OMBC drawn up by an international expert group. These statements can provide a basis for standardisation of future research, which will lead to high-quality evidence in the field.

Defining Oligometastatic Bladder Cancer: A Systematic Review

Context

Unlike other cancers, the concept of oligometastatic disease (OMD) in bladder cancer (BC) has not been systematically investigated. There is therefore a need to develop universally accepted definitions and guidelines for the management of oligometastatic BC (OMBC).

Objective

To conduct a systematic review to assist a European consensus group in producing a definition of OMBC and to provide recommendations on staging and local therapies.

Evidence acquisition

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. Abstracts for articles focused on BC that addressed the issue of OMBC and provided a definition of oligometastatic status were selected. We collected data on the number of metastases, the number of metastases per organ, the number of organs involved, and metastatic sites that were excluded.

Evidence synthesis

Sixteen eligible articles were retrieved (9 retrospective series involving 330 patients, 4 reviews, 1 consensus statement, 1 guideline paper, and 1 ongoing prospective phase 2 trial). A maximum of three to five metastatic lesions were compatible with the definition of OMBC. The number of organs involved and lesion size were not universally included in the OMBC definitions. OMD categories studied included synchronous OMBC, oligorecurrence, and oligoprogression. 18F-Fluorodeoxyglucose positron emission tomography combined with computed tomography was used in addition to conventional imaging for OMD detection. Surgery and radiotherapy were both used. Systemic chemotherapy was also used in all studies.

Conclusions

There is little information on OMBC in the literature. Our systematic review revealed that only three to five metastatic sites amenable to surgery or radiotherapy that respond to systemic therapy is the setting most frequently chosen for a combination of systemic treatment and metastases-directed therapy. This setting could represent a basis for future prospective studies on OMBC.

Patient summary

Oligometastatic bladder cancer is a disease state in which favorable outcomes can be expected after a treatment combination of systemic therapy, plus surgery and/or radiotherapy for sites of bladder cancer metastasis. Our systematic review showed a lack of meaningful evidence to define this disease state. There is an urgent need to develop organized research in this field.

Retrospective Analysis of a Cohort of Patients with Metastatic Bladder Cancer with Metastatic Sites Limited to the Pelvis and Retroperitoneum Treated at a Single Institution between 2009 and 2020

Bladder cancer (BC) presenting with pelvic and retroperitoneal lymph nodes presents a therapeutic challenge. The impact of chemoradiotherapy on pelvic and retroperitoneal lymph node metastasis as a consolidation treatment has not been established. Between 2009 and 2020, 502 patients who were treated with first-line chemotherapy for BC in our center, were retrospectively identified. Patients who received chemoradiotherapy or radiotherapy with an equivalent radiation dose superior to 30 Gy were included in the RTCT group, and other patients were included in the control group (CT group). We performed an analysis of progression-free survival (PFS) and overall survival (OS) for these two cohorts using the Kaplan–Meier method. A total of 89 patients were included, 24 in the RTCT group and 65 in the CT group. Chemoradiotherapy improved both OS (p = 0.034) and PFS (p = 0.009) in comparison with chemotherapy alone: 26.3 months (95% IC 0.0–52.9) and 19.4 months (95% IC 5.0–33.7), respectively, in the RTCT group versus 17.2 months (95% IC 13.7–20.6) and 11.2 months (95% IC 8.6–13.8), respectively, in the CT group. Grade 3/4 toxicity was related to chemotherapy and to chemoradiotherapy at levels of 31% and 24%, respectively. For mBC with metastatic regional or retroperitoneal lymph nodes, chemoradiotherapy seems to confer benefits for both OS and PFS.

Consolidative Radiotherapy for Metastatic Urothelial Bladder Cancer Patients with No Progression and with No More than Five Residual Metastatic Lesions Following First-Line Systemic Therapy: A Retrospective Analysis

Local consolidative radiotherapy in the treatment of metastatic malignancies has shown promising results in several types of tumors. The objective of this study was to assess consolidative radiotherapy to the bladder and to residual metastases in metastatic urothelial bladder cancer with no progression following first-line systemic therapy.

MATERIALS/METHODS

Patients who received first-line therapy for the treatment of metastatic urothelial bladder cancer (mUBC) and who were progression-free following treatment with no more than five residual metastases were retrospectively identified through the database of four Comprehensive Cancer Centers, between January 2005 and December 2018. Among them, patients who received subsequent definitive radiotherapy (of EQD2Gy > 45Gy) to the bladder and residual metastases were included in the consolidative group (irradiated (IR) group), and the other patients were included in the observation group (NIR group). Progression-free survival (PFS) and overall survival (OS) were determined from the start of the first-line chemotherapy using the Kaplan-Meier method. To prevent immortal time bias, a Cox model with time-dependent covariates and 6-month landmark analyses were performed to examine OS and PFS.

RESULTS

A total of 91 patients with at least stable disease following first-line therapy and with no more than five residual metastases were analyzed: 51 in the IR group and 40 in the NIR group. Metachronous metastatic disease was more frequent in the NIR group (19% vs. 5%, p = 0.02); the median number of metastases in the IR group vs. in the NIR group was 2 (1-9) vs. 3 (1-5) (p = 0.04) at metastatic presentation, and 1 (0-5) vs. 2 (0-5) (p = 0.18) after completion of chemotherapy (residual lesions), respectively. Two grade 3 toxicities (3.9%) and no grade 4 toxicity were reported in the IR group related to radiotherapy. With a median follow up of 85.9 months (95% IC (36.7; 101.6)), median OS and PFS were 21.7 months (95% IC (17.1; 29.7)) and 11.1 months (95% IC (9.9; 14.1)) for the whole cohort, respectively. In multivariable analysis, consolidative radiotherapy conferred a benefit in both PFS (HR = 0.49, p = 0.007) and OS (HR = 0.47, p = 0.015) in the whole population; in the landmark analysis at 6 months, radiotherapy was associated with improved OS (HR = 0.48, p = 0.026), with a trend for PFS (HR = 0.57, p = 0.082).

CONCLUSION

Consolidative radiotherapy for mUBC patients who have not progressed after first-line therapy and with limited residual disease seems to confer both OS and PFS benefits. The role of consolidative radiotherapy in the context of avelumab maintenance should be addressed prospectively.

Oligoprogression of Solid Tumors on Immune Checkpoint Inhibitors: The Impact of Local Ablative Radiation Therapy

The breakthrough of a limited number of clones while on immune checkpoint inhibitors (ICIs), known as oligoprogression, has been previously described. The benefit of ablative radiation therapy (RT) directed at these clones, as opposed to changing systemic therapy, is unclear. We analyzed 30 patients with advanced solid tumors, the majority of whom (23/30, 86.7%) had either hepatocellular or urothelial carcinoma, who experienced oligoprogression on ICIs and were referred for RT. In this study, oligoprogression was defined as having experienced progression at three or fewer metastatic sites outside of the brain after achieving at least stable disease on ICIs for a minimum of three months. The median time to oligoprogression was 11.1 months from the initiation of immunotherapy. 24 patients had one oligoprogressive lesion and six had two. The median radiation dose delivered was 4650 cGy in a median of five fractions. The median progression-free survival (PFS) after RT was 7.1 months, and the time to oligoprogression was not a significant predictor of PFS2. 26 patients continued on ICIs after RT. While 17 patients subsequently progressed, 15 did so at three or fewer metastatic sites and could have theoretically stood to benefit from an additional course of salvage RT to further extend the lifespan of their ICIs. Overall survival at 6, 12, and 24 months was 100.0%, 96.3%, and 82.8%, respectively. These results suggest that RT may provide a PFS benefit and extend the lifespan of ICIs in patients who experience oligoprogression. Regardless of PFS, however, overall survival in this population appears to be excellent.

Metastasis-Directed Radiation Therapy with Consolidative Intent for Oligometastatic Urothelial Carcinoma: A Systematic Review and Meta-Analysis

Simple Summary

Patients with oligometastatic urothelial carcinoma represent a challenging subset of subjects to manage. Herein we summarized evidence about the role of metastasis-directed radiation therapy in this clinical setting. Available preliminary evidence supports the role of metastasis-directed radiation therapy as a safe and efficacious option as it has the potential to facilitate local disease control and overall survival. However, in the absence of data from high-quality trials, definitive recommendations cannot be provided, and patients should be counseled on an individual basis.

Abstract

The management of patients with oligometastatic urothelial carcinoma (UC) represents an evolving field in uro-oncology, and the role of metastasis-directed therapies, including metastasectomy and metastasis-directed radiation therapy (MDRT), is gaining increasing attention. Herein, we summarize available evidence about the role of MDRT with consolidative intent in oligometastatic UC patients. A systematic review was performed in December 2021. Six studies involving 158 patients were identified. Most patients (n = 120, 90.2%) had a history of bladder cancer and the most frequent sites of metastases were lymph nodes (n= 61, 52.1%) followed by the lungs (n = 34, 29%). Overall, 144 metastases were treated with MDRT. Median follow-up ranged from 17.2 to 25 months. Local control rates ranged from 57% to 100%. Median Overall Survival (OS) ranged from 14.9 to 51.0 months and median progression-free survival ranged from 2.9 to 10.1 months. Rates of OS at one and two years ranged from 78.9% to 96% and from 26% to 63%, respectively. Treatment-related toxicity was recorded in few patients and in most cases a low-grade toxicity was evident. MDRT with consolidative intent represents a potential treatment option for selected patients with oligometastatic UC.

Survival in Metastatic Renal Cell Carcinoma Patients Treated With Sunitinib With or Without Cryoablation

Background

Percutaneous cryoablation (PCA) has emerged as an alternative to extirpative management of small renal masses in select patients. In recent years, the use of targeted therapies has become mainstream, while the role of PCA in treating primary tumor is not well established among patients with metastatic renal cell carcinoma (mRCC). We sought to evaluate how mRCC patients react to PCA in combination with sunitinib.

Methods

We retrospectively identified patients with mRCC (primary tumor diameter ≤ 7 cm) treated with sunitinib between 2013 and 2019. These patients were categorized by initial treatment (cryoablation followed by sunitinib versus sunitinib only). Oncological outcomes and rate of adverse events were compared.

Results

Of the 178 patients analyzed, 65 underwent PCA prior to sunitinib. The median overall survival (OS) in the PCA-sunitinib group was 31.7 months (95% CI; 26.1-37.3), better than the sunitinib-only group, which reported a median OS of 19.8 months (95% CI; 17.1-22.4) (p < 0.001). The median progression-free survival (PFS) in patients treated with PCA-sunitinib versus sunitinib alone was 13.8 months (95% CI; 10.0-17.6) versus 7.2 months (95% CI: 6.1-8.3) (p < 0.005). No significant differences in adverse events were observed (p > 0.05).

Conclusions

PCA combined with sunitinib is associated with better survival outcomes than sunitinib alone in patients with mRCC. Careful patient selection remains warranted. These results should inform future prospective trials.

Definitive radiotherapy for extracranial oligoprogressive metastatic renal cell carcinoma as a strategy to defer systemic therapy escalation

OBJECTIVE

To study whether delivering definitive radiotherapy (RT) to sites of oligoprogression in metastatic renal cell carcinoma (mRCC) enabled deferral of systemic therapy (ST) changes without compromising disease control or survival.

PATIENTS AND METHODS

We identified patients with mRCC who received RT to three or fewer sites of extracranial progressive disease between 2014 and 2019 at a large tertiary cancer centre. Inclusion criteria were: (1) controlled disease for ≥3 months before oligoprogression, (2) all oligoprogression sites treated with a biologically effective dose of ≥100 Gy, and (3) availability of follow-up imaging. Time-to-event end-points were calculated from the start of RT.

RESULTS

A total of 72 patients were identified (median follow-up 22 months, 95% confidence interval [CI] 19-32 months), with oligoprogressive lesions in lung/mediastinum (n = 35), spine (n = 30), and non-spine bone (n = 5). The most common systemic therapies before oligoprogression were none (n = 33), tyrosine kinase inhibitor (n = 23), and immunotherapy (n = 13). At 1 year, the local control rate was 96% (95% CI 87-99%); progression-free survival (PFS), 52% (95% CI 40-63%); and overall survival, 91% (95% CI 82-96%). At oligoprogression, ST was escalated (n = 16), maintained (n = 49), or discontinued (n = 7), with corresponding median (95% CI) PFS intervals of 19.7 (8.2-27.2) months, 10.1 (6.9-13.2) months, and 9.8 (2.4-28.9) months, respectively. Of the 49 patients maintained on the same ST at oligoprogression, 21 did not subsequently have ST escalation.

CONCLUSION

Patients with oligoprogressive mRCC treated with RT had comparable PFS regardless of ST strategy, suggesting that RT may be a viable approach for delaying ST escalation. Randomised controlled trials comparing treatment of oligoprogression with RT vs ST alone are needed.