Completeness of reporting oligometastatic disease characteristics in literature and influence on oligometastatic disease classification using the ESTRO/EORTC nomenclature

Maintaining First-Line Therapy Plus Radiation Therapy May Prolong Progression-Free Survival and Delay Second-Line Therapy for Oligoprogressive Hepatocellular Carcinoma

PURPOSE

Optimal treatment strategies for patients with hepatocellular carcinoma with oligoprogression after first-line systemic therapy (FLST) remain undefined. We aimed to determine whether maintaining (ie, continuing) FLST plus radiation therapy (RT) for oligoprogressive lesions (m-FLST + RT) would result in progression-free survival (PFS) equal to or greater than that of second-line systemic therapy (s-SLST), either alone or with RT (s-SLST + RT).

METHODS AND MATERIALS

From October 2018 to February 2024, 154 patients from 7 medical centers who developed oligoprogression after FLST were enrolled and assigned to 1 of 3 groups based on post-oligoprogression treatment strategy: m-FLST + RT, s-SLST + RT, or s-SLST-only. The primary outcome was PFS, and early patterns of recurrence were noted.

RESULTS

At a median follow-up time of 8.4 months, the median PFS time was longer in the m-FLST + RT group (8.6 months) compared with the s-SLS-only group (3.1 months) (hazard ratio, 3.163; 95% CI, 2.133-4.690; P < .001) and the s-SLST + RT group (5.8 months) (hazard ratio, 2.183; 95% CI, 1.110-4.293; P = .006). Multivariate Cox analysis demonstrated that albumin-bilirubin (ALBI) grade and postoligoprogression treatment strategy were independent prognostic factors for PFS. Stratified analysis by ALBI grade showed that m-FLST + RT resulted in significantly longer median PFS in patients with both ALBI-1 and ALBI-2 compared with s-SLST-only (P < .001). Regarding subsequent patterns of relapse, the m-FLST + RT group had a lower rate of re-enlargement of recently oligoprogressive lesions (27.6%) than the s-SLST + RT (31.8%) and s-SLST-only (50.0%) groups. It also had the lowest rate of re-enlargement of previously identified metastases that did not progress during FLST (13.8%) compared with s-SLRT + RT (27.3%) and s-SLST-only (24.4%).

CONCLUSIONS

Our study suggests a potential clinical benefit of m-FLST + RT without the need for s-SLST and provides insights to optimize treatment strategies for oligoprogressive hepatocellular carcinoma.

Comprehensive cohort study: computer tomography-guided high-dose rate brachytherapy as metastasis-directed therapy for liver metastases from colorectal cancer in repeat oligoprogression

PURPOSE

The standard treatment for oligometastatic colorectal cancer includes systemic therapy, with surgery and metastasis-directed therapy as options. The optimal strategy, especially for repeat oligoprogression (rOP), remains unclear. We report outcomes of liver computer tomography-guided high-dose rate brachytherapy (CT-BRT) in this setting.

METHODS

This retrospective cohort study included colorectal cancer patients with liver-only oligoprogression during systemic therapy, meeting criteria of up to 5 liver metastases, CT-BRT eligibility, and ECOG status ≤ 2. Patients were followed for local response, progression-free survival (PFS), overall survival (OS), and toxicity. Response, according to RECIST 1.1, was initiated 6 months post-CT-BRT.

RESULTS

A total of 262 metastases were treated in 127 patients, with 67.7% receiving third-line or later systemic therapies. One to four liver metastases were found in 29.1%, 42.5%, 21.2%, and 7.1% of patients, respectively, with a median volume of 128 cm3. A median of 3 applicators was used, with CT-BRT doses of 15 Gy, 20 Gy, and 25 Gy given to 29.9%, 41.7%, and 28.3% of patients. At 6 months complete response occurred in 3.1%, progressive disease in 23.6%, partial response in 19.7%, and stable disease in 53.5%. Median PFS was 9 months, median OS was 16 months, with 1-year and 2-year OS rates of 65% and 16%, respectively. Liver-only metastases and objective response were associated with longer PFS. The G3 toxicity was 4.0%; no events > G3 were reported.

CONCLUSIONS

This largest study documents favorable outcomes of liver CT-BRT for rOP, establishing this method as a viable option in this indication.

Efficacy and safety of radiotherapy to delay second-line systemic therapy in patients with oligoprogressive hepatocellular carcinoma: study protocol of a multicentre, single-arm, phase II trial

Background

Hepatocellular carcinoma (HCC) is a highly aggressive cancer with a paucity of efficacious treatment options, particularly in advanced stages following first-line systemic therapy (FLST).

Objectives

The objective of this trial is to assess the efficacy and safety of radiotherapy as a treatment option to prolong progression-free survival (PFS) and delay the necessity for second-line systemic therapy (SLST) in patients with oligoprogressive HCC following FLST.

Design

Multicentre, single-arm, phase II trial.

Methods and analysis

This prospective, multicentre, single-arm phase II clinical trial will enrol 36 patients with oligoprogressive advanced HCC following FLST. A comprehensive clinical imaging evaluation will be conducted to confirm the presence of oligoprogressive disease, categorized as metachronous oligoprogression, repeat oligoprogression or induced oligoprogression. Furthermore, patients must have demonstrated stability of the primary HCC for a minimum of 3 months during FLST. Eligible patients will receive radiotherapy for all oligoprogressive lesions with a biologically effective dose (LQ, α/β = 10) of at least 60 Gy while continuing their current FLST until disease progression necessitates SLST. The primary endpoint is PFS, with secondary endpoints including objective remission rate, overall survival (OS), disease control rate, safety and duration of disease remission.

Ethics

The final protocol was approved by the Ethics Committee of the Affiliated Cancer Hospital of Shandong First Medical University.

Discussion

Given the greater number of options for FLST in advanced HCC, which have demonstrated improvements in PFS and OS, and the limited number and less effective SLST options, this phase II trial aims to evaluate the use of radiotherapy to extend PFS and delay the application of SLST in patients with oligoprogressive HCC after FLST. This approach may preserve SLST options for more aggressive, widespread metastatic disease in the future.

Trial registration

This study is registered on ClinicalTrials.gov identifier: NCT06261047.

Survival Without Quality of Life Deterioration in the GORTEC 2014-04 "OMET" Randomized Phase 2 Trial in Patients with Head and Neck Cancer with Oligometastases using Stereotactic Ablative Radiation Therapy (SABR) alone or Chemotherapy and SABR

PURPOSE

Patients with oligometastasis may have prolonged survival with multisite stereotactic ablative radiation therapy (SABR). Evidence to support this paradigm is scarce in squamous cell carcinoma of the head and neck (HNSCC). The multicenter open-label randomized GORTEC 2014-04 (NCT03070366) phase 2 study assesses survival without definitive quality of life (QoL) deterioration of omitting upfront chemotherapy in oligometastatic patients with HNSCC using SABR alone, in the French Head and Neck Intergroup.

METHODS AND MATERIALS

Eligible participants (≥18 years old with 1-3 oligometastases, the Eastern Cooperative Oncology Group score 0-2) were randomly assigned (1:1) to receive chemo-SABR or SABR alone. Salvage treatments were left to the physician's appreciation. The standard therapy was considered to be systemic therapy and SABR (chemo-SABR; EXTREME regimen [5 fluorouracil/platinum/cetuximab]). The primary endpoint was 1-year (±3 months) overall survival rate without definitive deterioration (ie, without subsequent better QoL score) of the global European Organisation for Research and Treatment of Cancer QoL Questionnaire-Core30 score.

RESULTS

Between September 2015 and October 2022, 69 participants were assigned to receive chemo-SABR (N = 35) or SABR alone (N = 34); 57 had lung-only metastases (82.6%), and 40 had isolated metastasis (58.0%). The median baseline QoL score was 66.7 (IQR, [50.0-83.3]). The median follow-up was 55.3 months (95% CI, 45.0-69.7). Of participants (N = 59) evaluable for the primary endpoint, 16 of 29 (55.2%, 90% CI, 0.38-0.71) and 16 of 30 (53.3%, 90% CI, 0.37-0.69) were alive and free of QoL deterioration at 1 year in the SABR-alone and chemo-SABR arms. However, QoL deterioration was deeper with chemo-SABR (50.0; IQR, [41.7-66.7]) than with SABR alone (16.7; IQR, [16.7-41.7]). In intent-to-treat analysis (N = 69), median survival was 42.3 months (95% CI, 26.5-not reached) with chemo-SABR and 41.1 months (95% CI, 32.1-66.9) with SABR alone; median progression-free survival was 12.9 (95% CI, 7.5-17.3) and 7.4 months (95% CI, 4.2-15.6) in the chemo-SABR and SABR alone arms, respectively. Rates of severe treatment-related toxicities were 21 of 35 (60.0%) with chemo-SABR and 3 of 34 (8.8%, no grade 5) with SABR alone.

CONCLUSIONS

Using SABR alone, the omission of upfront EXTREME-based chemotherapy and maintenance cetuximab in oligometastatic patients with HNSCC resulted in similar survival but much less severe QoL deterioration and fewer toxicity rates. SABR alone could be a reasonable alternative in oligometastatic patients with HNSCC.

A new proposal of simplified classification of non-small cell lung cancer oligometastases for easy applicability through systematic literature analysis and meta-analysis validation

INTRODUCTION

Oligometastasis (OM) exhibits wide range of prognosis, which necessitates appropriate classification for optimal therapeutic decision-making. Complementing the ESTRO-EORTC classification which lacked prognostic differentiation and was rather complex, we propose a new and simpler classification based on systematic literature analysis and meta-analysis validation.

METHOD

The databases were searched up to April 2024. Inclusion criteria were (1) ≥ 10 Non-small cell lung cancer OM patients, (2) local ablative treatment (LAT) versus control (systemic/supportive treatment), (3) reporting progression free survival (PFS) or overall survival (OS), respectively. A simpler classification was proposed through systematic reviews evaluating outcomes based on OM characteristics. According to this new classification, the LAT benefit and pooled 2-year OS and 1-year PFS percentiles were validated through meta-analysis.

RESULTS

In overall meta-analysis, LAT was correlated with enhanced 1-year PFS (odds ratio (OR):3.487, p < 0.001) and 2-year OS (OR:2.984, p < 0.001), respectively. According to simplified classification, LAT benefit of 1-year PFS was differentiated with ORs of 5.631 (p < 0.001), 3.484 (p < 0.001), and 1.702 (p = 0.067) for Synchronous (Syn), OPS (Oligopersistence), and OPR (Oligoprogression/recurrence) subgroups, respectively. Inter-subgroup comparisons showed significant differences as well. For 2-year OS, ORs of LAT benefit were 3.366 (p < 0.001), 3.355 (p < 0.001), and 1.821 (p = 0.127) in Syn, OPS, and OPR subgroups, respectively; LAT benefit was significant in Syn and OPS, but not significant in OPR. In pooled percentile comparison, 1-year pooled PFS was significantly lower in the OPR group than others, both in the LAT and control arms.

CONCLUSION

Based on a systematic literature analysis and meta-analysis validation, we developed a simpler three-step OM classification: Syn, OPS, and OPR. We would propose this new classification that is simpler and more applicable to clinical decisions than the currently available classification.

Radiation Oncologists' Perspectives on Oligometastatic Prostate Cancer: A Survey from Korean Oligometastasis Working Group

BACKGROUND

Interest in the oligometastatic prostate cancer (OMPC) is increasing, and various clinical studies have reported the benefits of metastasis-directed radiation therapy (MDRT) in OMPC. However, the recognition regarding the adopted definitions, methodologies of assessment, and therapeutic approaches is diverse among radiation oncologists. This study aims to evaluate the level of agreement for issues in OMPC among radiation oncologists.

METHODS

We generated 15 key questions (KQs) for OMPC relevant to definition, diagnosis, local therapies, and endpoints. Additionally, three clinical scenarios representing synchronous metastatic prostate cancer (mPC) (case 1), metachronous mPC with visceral metastasis (case 2), and metachronous mPC with castration-resistance and history of polymetastasis (case 3) were developed. The 15 KQs were adapted according to each scenario and transformed into 23 questions with 6-9 per scenario. The survey was distributed to 80 radiation oncologists throughout the Republic of Korea. Answer options with 0.0-29.9%, 30-49.9%, 50-69.9%, 70-79.9%, 80-89.9%, and 90-100% agreements were considered as no, minimal, weak, moderate, strong, and near perfect agreement, respectively.

RESULTS

Forty-five candidates voluntarily participated in this study. Among 23 questions, near perfect (n = 4), strong (n = 3), or moderate (n = 2) agreements were shown in nine. For the case recognized as OMPC with agreements of 93% (case 1), near perfect agreements on the application of definitive radiation therapy (RT) for whole metastatic lesions were achieved. While ≥70% agreements regarding optimal dose-fractionation for metastasis-directed RT (MDRT) has not been achieved, stereotactic body RT (SBRT) is favored by clinicians with higher clinical volume.

CONCLUSION

For the case recognized as OMPC, near perfect agreement for the application of definitive RT for whole metastatic lesions was reached. SBRT was more favored as a MDRT by clinicians with a higher clinical volume.

Metastasis-directed therapy in oligometastatic prostate cancer

PURPOSE OF REVIEW

To summarize the recent findings on the subject of metastasis-directed therapy (MDT) in the treatment of oligometastatic prostate cancer (omPCa).

RECENT FINDINGS

Evidence from two randomized clinical trials (RCTs) and a meta-analysis show favorable toxicity profiles, and the potential to delay androgen-deprivation therapy (ADT) for up to two years in nearly half of patients with metachronous hormone-sensitive omPCa. Another RCT showed promising results of MDT as treatment-escalation method combined with androgen receptor signaling inhibitors (ARSI) in first-line treatment for castration-resistant omPCa.Surveys by radiation oncologists and consensus guidelines advocate for MDT across various omPCa scenarios. Multiple single-arm trials present encouraging results; however, the evidence for the benefit of MDT is still weak requiring further investigation to assess its impact on pivotal endpoints, such as survival and quality of life.

SUMMARY

MDT is a promising approach in omPCa, and can be used to defer ADT in newly diagnosed metachronous omPCa patients, or to add to ARSI treatment at first diagnosis of castration-resistance. Ongoing prospective trials are needed to guide its optimal utilization in other settings, and patients should be informed about the evolving landscape of systemic therapies with proven survival benefits alongside MDT options.

Prognostic Factors of Oligometastasis After Stereotactic Body Radiotherapy: The Real-World Utility of the European Society for Radiotherapy and Oncology/European Organisation for Research and Treatment of Cancer Classification

AIM

The efficacy of local therapy for oligometastatic disease (OMD) remains unclear. This study aimed to evaluate the prognostic utility of the classification system for OMD and explore which groups may benefit from stereotactic body radiation therapy (SBRT).

METHODS

This single-center retrospective study included 45 patients (52 sites) with solid tumors and 1-3 extracranial oligometastases who underwent SBRT for all metastases at our institution between January 2018 and December 2021. OMD states were classified based on the European Society for Radiotherapy and Oncology (ESTRO) and the European Organisation for Research and Treatment of Cancer (EORTC) classification system. Local control (LC), overall survival (OS), and progression-free survival (PFS) for each group were analyzed using the Kaplan-Meier method. Acute and late adverse events (AEs) were evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

RESULTS

The median follow-up period was 14 months (range: 0-48 months). The numbers of patients in the de novo (first diagnosis of OMD), repeat (previous history of OMD), and induced (previous history of polymetastatic disease) OMD groups were 15, 17, and 13, respectively. The LC rates at one year for the entire, de novo, repeat, and induced cohorts were 87.2%, 87.5%, 90.2%, and 83.9%, respectively (p=0.80). The one-year PFS rates for each group were 35.0%, 56.7%, and 29.9%, respectively (p=0.58). The one-year OS rates for each group were 80.0%, 86.2%, and 80.8%, respectively (p=0.50). Grade 2 or 3 AEs occurred in five patients (10.4%). No grade 4 or 5 AEs were observed.

CONCLUSIONS

SBRT is safe and highly effective for local control. Patients with repeat OMD demonstrated a trend of longer PFS, suggesting that this subgroup may benefit from local therapy at metastatic sites.

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.

Radiation Oncologists' Perspectives on Oligometastatic Disease: A Korean Survey Study

PURPOSE

Perspectives of radiation oncologists on oligometastatic disease was investigated using multi-layered survey.

MATERIALS AND METHODS

Online survey on the oligometastatic disease was distributed to the board-certified regular members of the Korean Society for Radiation Oncology. The questionnaire consisted of four domains: five questions on demographics; five on the definition of oligometastatic disease; four on the role of local therapy; and three on the oligometastatic disease classification, respectively.

RESULTS

A total of 135 radiation oncologists participated in the survey. The median length of practice after board certification was 22.5 years (range, 1 to 44 years), and the vast majority (94.1%) answered affirmatively to the clinical experience in oligometastatic disease management. Nearly two-thirds of the respondents considered the number of involved organs as an independent factor in defining oligometastasis. Most frequently perceived upper limit on the numerical definition of oligometastasis was 5 (64.2%), followed by 3 (26.0%), respectively. Peritoneal and brain metastasis were nominated as the sites to be excluded from oligometastastic disease by 56.3% and 12.6% of the participants, respectively. Vast majority (82.1%) agreed on the role of local treatment in the management of oligometastatic disease. Majority (72%) of the participants acknowledged the European Society for Radiotherapy and Oncology (ESTRO)-European Organisation for Research and Treatment of Cancer (EORTC) classification of oligometastatic disease, however, only 43.3% answered that they applied this classification in their clinical practice. Underlying reasons against the clinical use were 'too complicated' (66.0%), followed by 'insufficient supporting evidence' (30.0%), respectively.

CONCLUSION

While most radiation oncologists supported the role of local therapy in oligometastatic disease, there were several inconsistencies in defining and categorizing oligometastatic disease. Continued education and training on oligometastatic disease would be also required to build consensus among participating caregivers.

Metastases-directed local therapies (MDT) beyond genuine oligometastatic disease (OMD): Indications, endpoints and the role of imaging

To further personalise treatment in metastatic cancer, the indications for metastases-directed local therapy (MDT) and the biology of oligometastatic disease (OMD) should be kept conceptually apart. Both need to be vigorously investigated. Tumour growth dynamics - growth rate combined with metastatic seeding efficiency - is the single most important biological feature determining the likelihood of success of MDT in an individual patient, which might even be beneficial in slowly developing polymetastatic disease. This can be reasonably well assessed using appropriate clinical imaging. In the context of considering appropriate indications for MDT, detecting metastases at the edge of image resolution should therefore suggest postponing MDT. While three to five lesions are typically used to define OMD, it could be argued that countability throughout the course of metastatic disease, rather than a specific maximum number of lesions, could serve as a better parameter for guiding MDT. Here we argue that the unit of MDT as a treatment option in metastatic cancer might best be defined not as a single procedure at a single point in time, but as a series of treatments that can be delivered in a single or multiple sessions to different lesions over time. Newly emerging lesions that remain amenable to MDT without triggering the start of a new systemic treatment, a change in systemic therapy, or initiation of best supportive care, would thus not constitute a failure of MDT. This would have implications for defining endpoints in clinical trials and registries: Rather than with any disease progression, failure of MDT would only be declared when there is progression to polymetastatic disease, which then precludes further options for MDT.

Stereotactic body radiation therapy for the treatment of lymph node metastases: a retrospective mono-institutional study in a large cohort of patients

Introduction

Lymph node metastases (NMs) are a common site of tumor spread that can occur at different times of the disease. Stereotactic body radiation therapy (SBRT) can be a therapeutic option for the treatment of NMs in the setting of oligometastatic disease (OMD). The aim of this study was to evaluate as primary end points the local control (LC) and secondary end points the locoregional nodal control (LRNC), distant nodal control (DNC), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS), and concurrently to assess the predictive factors of response.

Methods

This is a retrospective study that analyzes a group of patients treated with SBRT on NMs from different primary tumors, with a of maximum five metastasis. Treated lesions were divided into four groups: oligometastatics, oligorecurrents, oligoprogressives, and oligopersistents.

Results

From 2007 to 2021, 229 NMs were treated in 174 patients with different primary tumor. The schedule most represented was 30 Gy in five fractions. The LC was obtained in 90% of NMs treated by SBRT with rates at 1, 3, and 5 years of 93%, 86%, and 86%, respectively. The LRNC was reached in 84% of cases with rates at 1, 3, and 5 years of 88%, 83%, and 77%, respectively. The DNC was obtained in 87% of cases with rates at 1, 3, and 5 years of 92%, 82%, and 78%, respectively. The DMFS was obtained in 38% of cases with rates at 1, 3, and 5 years of 57%, 40%, and 30%, respectively. The rate of PFS were 44%, 23%, and 13% at 1, 3, and 5 years, respectively. The rates at 1, 3, and 5 years of OS were 78%, 48%, and 36%, respectively.

Conclusion

SBRT is an option for the treatment of NMS, with high rates of LC, improving survival, and with a good safety and tolerance. Tumor volume, tumor burden, lesion site, and doses can be predictive factors of response; however, multi-institutional studies with a greater number of patients could be helpful to better select patients and understand the right integrations between ablative treatment and systemic therapies.

Local Therapies for Metastatic Sarcoma: Why, When, and How?

Management of patients with advanced sarcoma has been evolving in recent decades, from a one-fit-all perspective to a more refined, personalized, and multidisciplinary approach. In parallel, the evolution of local therapies (radiotherapy, surgical and interventional radiology techniques) has contributed to the improvement of survival of patients with advanced sarcoma. In this article, we review the evidence regarding local treatments in advanced sarcoma, as well as its integration with systemic therapies, to provide the reader a wider and deeper perspective on the management of patients with metastatic sarcoma.

Clinical Outcomes of Patients with Metastatic Breast Cancer Treated with Hypo-Fractionated Liver Radiotherapy

PURPOSE

To retrospectively review the clinical outcomes of patients with metastatic breast cancer (MBCa) following liver directed ablative intent radiotherapy (RT).

METHODS

Demographics, disease and treatment characteristics of patients with MBCa who received liver metastasis (LM) directed ablative RT between 2004-2020 were analysed. The primary outcome was local control (LC), secondary outcomes included overall survival (OS) and progression-free survival (PFS) analyzed by univariate (UVA) and multi-variable analysis (MVA).

RESULTS

Thirty MBCa patients with 50 LM treated with 5-10 fraction RT were identified. Median follow-up was 14.6 (range 0.9-156.2) months. Class of metastatic disease was described as induced (12 patients, 40%), repeat (15 patients, 50%) and de novo (three patients, 10%). Median size of treated LM was 3.1 cm (range 1-8.8 cm) and median biologically effective dose delivered was 122 (Q1-Q3; 98-174) Gy₃. One-year LC rate was 100%. One year and two-year survival was 89% and 63%, respectively, with size of treated LM predictive of OS (HR 1.35, p = 0.023) on UVA. Patients with induced OMD had a significantly higher rate of progression (HR 4.77, p = 0.01) on UVA, trending to significance on MVA (HR 3.23, p = 0.051).

CONCLUSIONS

Hypo-fractionated ablative liver RT in patients with MBCa provides safe, tolerable treatment with excellent LC.

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.