Characterisation and classification of oligometastatic disease: a European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer consensus recommendation

OligoM-Cancer: A multidimensional information platform for deep phenotyping of heterogenous oligometastatic cancer

Patients with oligometastatic cancer (OMC) exhibit better response to local therapeutic interventions and a more treatable tendency than those with polymetastatic cancers. However, studies on OMC are limited and lack effective integration for systematic comparison and personalized application, and the diagnosis and precise treatment of OMC remain controversial. The application of large language models in medicine remains challenging because of the requirement of high-quality medical data. Moreover, these models must be enhanced using precise domain-specific knowledge. Therefore, we developed the OligoM-Cancer platform (http://oligo.sysbio.org.cn), pioneering knowledge curation that depicts various aspects of oligometastases spectrum, including markers, diagnosis, prognosis, and therapy choices. A user-friendly website was developed using HTML, FLASK, MySQL, Bootstrap, Echarts, and JavaScript. This platform encompasses comprehensive knowledge and evidence of phenotypes and their associated factors. With 4059 items of literature retrieved, OligoM-Cancer includes 1345 valid publications and 393 OMC-associated factors. Additionally, the included clinical assistance tools enhance the interpretability and credibility of clinical translational practice. OligoM-Cancer facilitates knowledge-guided modeling for deep phenotyping of OMC and potentially assists large language models in supporting specialised oligometastasis applications, thereby enhancing their generalization and reliability.

Different approach to M descriptor for future staging of oligometastatic disease in SCLC: A cross-sectional survival analysis

PURPOSE

This study aimed to investigate the impact of oligometastasis and the M descriptor on survival in small cell lung cancer (SCLC).

METHODS

This multicenter, retrospective study included patients with newly diagnosed extensive-stage SCLC(ES-SCLC) from 2010 to 2020. Subgroups: Group 1: single metastasis in a single organ, Group 2: 2-5 metastases in a single organ, Group 3: 6 or more metastases in a single organ, and Group 4: metastases in two or more organs. This classification was based on the 9th Staging-M descriptor. Three-year progression-free survival (PFS) and overall survival (OS) analyses were conducted.

RESULTS

The mean age of the 439 patients was 62 ± 10 years, and 89.5% of them were male. The mean PFS for Groups 1, 2, 3, 4 was 10.7 months (95% CI 8.9-12.5), 7.5 months (95% CI 5.6-9.4), 4.3 months (95% CI 2.9-5.7), and 5.4 months (95% CI 4.7-6.1), respectively. PFS in Group 2 was significantly higher. The mean OS for Groups 1, 2, 3, 4 was 13.3 months (95% CI 11.2-15.3), 9.5 months (95% CI 7.1-11.9), 7.1 months (95% CI 4.5-9.7), and 6.9 months (95% CI 6.0-7.9), respectively. OS in Group 1 was significantly higher. OS and PFS in the M1b group were significantly higher than in the M1c1 and M1c2 groups (p < 0.05) with no statistical difference between the M1c1 and M1c2 groups.

CONCLUSION

There is no significant difference in survival between the M1c1 and M1c2 groups. In ES-SCLC, the number of metastases may be a more predictive factor for prognosis than the number of metastatic organs.

The Landmark Series: Multimodal Management of Oligometastatic Sarcoma

The concept of "oligometastatic" disease suggests the presence of intermediate states between localized disease and widespread metastases, which may be potentially treatable with curative therapeutic strategies. Metastases local therapy (MLT) can be accomplished through various techniques such as stereotactic ablative radiotherapy (SABR), radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation, or surgical metastasectomy. The incorporation of MLT in the multidisciplinary treatment of patients with metastatic sarcoma is complex. Retrospective studies support consideration of MLT for selected patients based on factors such as patient condition, disease biology, histologic type, and disease burden. Decisions regarding type and timing of MLT should be made after multidisciplinary discussion including radiation oncologists, surgical and orthopedic oncologists, medical oncologists, and interventional radiology to explore all options before treatment decsions. All MLT techniques have advantages and disadvantages and should be performed in centers specialized in the care of complex oncology patients where various options can be explored concurrently or sequentially for each patient. Future studies evaluating quality of life and patient-reported outcomes are necessary to adequately align patient goals and optimal outcomes. This article reviews the medical scenarios that may benefit the use of MLT, evaluates the distinct advantages and disadvantages associated with these various techniques, and analyzes the findings from pivotal series to provide a comprehensive understanding of its role in clinical practice.

Role of stereotactic radiotherapy in the management of small-cell lung cancer

Small-cell lung cancer is the most aggressive form of lung neoplasia, treated in recent decades with chemoradiotherapy in case of limited stage and chemotherapy alone at the metastatic stage. In the last few years, the advent of immunotherapy has changed the landscape in the treatment of non-small-cell lung cancer, and to a lesser degree in small-cell lung cancer. Despite the recent advances in research, small-cell lung cancer is still considered an aggressive and lethal disease characterized by high recurrence or metastatic potential. As stereotactic radiotherapy has established itself as the standard of care in the early stage of inoperable non-small-cell lung cancer and in metastatic disease to treat brain and extracranial metastases, these same issues now arise in the management of small-cell lung cancer. This article aims to review the current knowledge and the potential of stereotactic radiotherapy in small-cell lung cancer.

Durable local control with hypofractionated radiation therapy for unresectable or metastatic melanoma

Background and purpose

As patients with advanced melanoma live longer in the context of systemic therapy advancements, better strategies for durable control of bulky tumors are needed. In this study, we evaluated if dose-escalated hypofractionated radiation therapy (HFRT) can provide durable local control and improve tumor-associated symptoms in patients with unresectable or bulky metastatic melanoma for whom stereotactic ablative radiotherapy (RT) approaches are not feasible due to tumor size or location.

Materials and methods

We retrospectively reviewed 49 patients with unresectable or bulky metastatic melanoma who were treated to a total of 53 tumor targets with 12-17 fractions HFRT at our institution between 2015-2022. Clinical scenarios included: unresectable, locoregional only disease (26 %); oligometastatic disease (<3 total sites, 17 %); oligoprogressive disease (<3 sites progressing, 17 %); and aggressive palliation (>5 known sites of disease or with at least 3 sites progressing, 40 %).

Results

Of the 53 HFRT targets, 91 % (n = 48) had radiographic evidence of response as defined by either stabilization (6 %, n = 3), decreased size (74 %, n = 39), or decreased FDG avidity (11 %, n = 6). Of the 43 symptomatic patients, 98 % (n = 42) had symptomatic improvement. One -year local control was 79 %, with 2-year progression-free and overall survival of 33 % and 39 % respectively. The most common acute toxicities were radiation dermatitis (16 %, n = 8) or a pain flare (14 %, n = 7). Late toxicities were uncommon and typically grade 1.

Conclusion

HFRT provides favorable local control and symptomatic relief with limited toxicity in tumors not amenable to surgical resection or stereotactic ablative RT.

Immune checkpoint inhibitors rechallenge in non-small cell lung cancer: Current evidence and future directions

Immunotherapy, remarkably immune checkpoint inhibitors (ICIs), has significantly altered the treatment landscape for non-small cell lung cancer (NSCLC). Despite their success, the discontinuation of ICIs therapy may occur due to factors such as prior treatment completion, disease progression during ICIs treatment, or immune-related adverse events (irAEs). As numerous studies highlight the dynamic nature of immune responses and the sustained benefits of ICIs, ICIs rechallenge has become an attractive and feasible option. However, the decision-making process for ICIs rechallenge in clinical settings is complicated by numerous uncertainties. This review systematically analyses existing clinical research evidence, classifying ICIs rechallenge into distinct clinical scenarios, exploring methods to overcome ICIs resistance in rechallenge instances, and identifying biomarkers to select patients likely to benefit from rechallenge. By integrating recent studies and new technologies, we offer crucial recommendations for future clinical trial design and provide a practical guideline to maximize the therapeutic benefits of immunotherapy for NSCLC patients.

Outcomes and prognostic factors in patients with synchronous and metachronous oligometastatic urothelial carcinoma with visceral metastases

OBJECTIVES

To evaluate the clinical characteristics of oligometastatic disease (OMD) in metastatic urothelial carcinoma (mUC) with visceral metastases when classified into synchronous and metachronous metastases.

METHODS

Of 957 cases of de novo mUC treated between 2008 and 2023, 374 with visceral metastases were analyzed. Cases were classified into OMD with up to three metastatic lesions and polymetastatic disease (PMD), and into synchronous and metachronous metastases. The clinical characteristics and overall survival (OS) for each group were analyzed.

RESULTS

Overall, 196 (52.4%) had synchronous metastasis and 178 (47.6%) had metachronous metastasis. Median OS for synchronous metastases was significantly shorter than for metachronous metastases (12.1 months vs. 15.3 months, p = 0.011). Among the synchronous metastases, 48 (24.5%) were OMD and 148 (75.6%) were PMD. There was no significant difference in OS between the OMDs and PMDs (median 14.9 months vs. 11.7 months, p = 0.32), and only decreased albumin level was identified as a significant predictor of poor OS. Among the metachronous metastases, 64 (36.0%) were OMD and 114 (64.0%) were PMD. There was no significant difference in OS between the OMD and PMD (median 21.2 months vs. 15.0 months, p = 0.35), and no significant predictors of poor OS were identified.

CONCLUSIONS

For mUC with visceral metastases, the timing of metastasis appearance was associated with prognosis, with synchronous metastases being a poorer prognostic factor compared to metachronous metastases. There was no prognostic difference between OMD and PMD with visceral metastases when classified into synchronous or metachronous metastases.

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.

Emerging Indications for Interventional Oncology: A Comprehensive Systematic Review of Image-Guided Thermal Ablation for Metastatic Non-cervical Lymph Node Disease

INTRODUCTION

Lymphatic node metastatic disease encompasses a distinct oncological entity which has been associated with poor prognosis. Image-guided thermal ablation has recently been proposed as a safe and alternative treatment for these lesions. The aim of this systematic review is to evaluate the pooled safety and efficacy of thermal ablation techniques for the treatment of oligometastatic non-cervical lymph nodal disease.

RECENT FINDINGS

A systematic search of the three major databases (MEDLINE, EMBASE, and CENTRAL) from inception to 30 December 2023 was conducted according to the PRISMA Guidelines. Observational studies reporting technical success, complications and oncologic outcomes were included. Meta- analysis was performed by estimating the pooled incidence rates and risk ratios by fitting random-effect models. Overall, 8 studies were included, comprising of 225 patients and 305 ablated LNMs and a median follow-up of 12 months. The combined data analysis showed that technical success after thermal ablation was 98% (CI: 95%-99%), major complication rate was 1% (CI: 95%-99%), pooled overall response rate was 72% (CI: 54%-87%), local tumor progression rate was 18% (CI: 8%-33%) and disease-free survival rate was 68% (CI: 51%-81%). No difference between radiofrequency ablation and cryoablation was found for every outcome during subgroup analysis. Image-guided percutaneous thermal ablation (with either radiofrequency ablation or cryoablation) is safe and effective for the treatment of oligometastatic LMN disease, however further studies to confirm these findings are still needed.

Influence of brain metastases on the classification, treatment, and outcome of patients with extracranial oligometastasis: a single-center cross-sectional analysis

BACKGROUND AND INTRODUCTION

Increasing evidence suggests that a subgroup of patients with oligometastatic cancer might achieve a prolonged disease-free survival through local therapy for all active cancer lesions. Our aims are to investigate the impact of brain metastases on the classification, treatment, and outcome in these patients.

MATERIALS AND METHODS

We analyzed a total of 7,000 oncological positron emission tomography scans to identify patients with extracranial oligometastatic disease (defined as ≤ 5 intra- or extra-cranial metastases). Concurrent magnetic resonance imaging brain was assessed to quantify intracranial tumor burden. We investigated the impact of brain metastases on oligometastatic disease state, therapeutic approaches, and outcome. Predictors for transitioning from oligo- to polymetastatic states were evaluated using regression analysis.

RESULTS

A total of 106 patients with extracranial oligometastases and simultaneous brain metastases were identified, primarily originating from skin or lung/pleura cancers (90%, n = 96). Brain metastases caused a transition from an extracranial oligometastatic to a whole-body polymetastatic state in 45% (n = 48) of patients. While oligometastatic patients received systemic therapy (55% vs. 35%) more frequently and radiotherapy for brain metastases was more often prescribed to polymetastatic patients (44% vs. 26%), the therapeutic approach did not differ systematically between both sub-groups. The oligometastatic sub-group had a median overall survival of 28 months compared to 10 months in the polymetastatic sub-group (p < 0.01).

CONCLUSION

In patients with brain metastases, a low total tumor burden with an oligometastatic disease state remained a significant prognostic factor for overall survival. Presence of brain metastases should therefore not serve as exclusion criterion for clinical trials in the field of oligometastatic disease. Moreover, it underscores the importance of considering a multimodality treatment strategy in oligometastatic cancer patients.

Stereotactic Body Radiation therapy for Liver Metastases: Systematic Review and Meta-Analysis With International Stereotactic Radiosurgery Society (ISRS) Practice Guidelines

PURPOSE

Liver metastases are a significant clinical challenge in cancer management, often representing a stage of disease in which curative treatment is still possible. Stereotactic body radiation therapy (SBRT) has emerged as a promising modality for treating these metastases, offering a noninvasive approach with potential for high efficacy. This systematic review and meta-analysis provides a comprehensive analysis of the efficacy and safety of SBRT in treating liver metastases, and practice recommendations are provided.

METHODS AND MATERIALS

We performed a thorough literature review, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach, and included 33 studies with a total of 3101 patients and 4437 liver metastases.

RESULTS

The review revealed pooled local control rates at 1, 2, and 3 years of 85%, 75%, and 68% respectively, while overall survival rates were 79%, 54%, and 37%. Grade 3 and 4 side effects occurred in only 3% of patients. The review of the studies highlighted the importance of factors such as primary tumor histology, lesion characteristics, and radiation dose in predicting treatment outcomes.

CONCLUSIONS

This review supports the growing body of evidence that SBRT is an efficacious and safe treatment option for liver metastases. It underscores the need for careful patient selection and personalized treatment planning to optimize outcomes.

Thoracic Radiotherapy Improves the Survival in Patients With EGFR-Mutated Oligo-Organ Metastatic Non-Small Cell Lung Cancer Treated With Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors: A Multicenter, Randomized, Controlled, Phase III Trial

PURPOSE

This multicenter, randomized, phase III clinical trial (Northern Radiation Oncology Group of China-002) focused on patients with oligo-organ metastatic non-small cell lung cancer (NSCLC) who have epidermal growth factor receptor (EGFR) mutations. We aimed to investigate whether first-line concurrent thoracic radiotherapy (TRT) and EGFR-tyrosine kinase inhibitors (TKIs), compared with TKIs alone, could achieve better survival.

MATERIALS AND METHODS

The patients in the TKI plus TRT group received 60 Gy to primary lung tumor and positive regional lymph nodes. Radiotherapy for metastases to other sites was determined by clinicians. The primary end point was the progression-free survival (PFS). Secondary end points included overall survival (OS) and treatment-related adverse events (TRAEs). The first and second interim analyses were performed in March 2021 and March 2022.

RESULTS

Between April 14, 2016, and February 25, 2022, a total of 118 patients were enrolled. Compared with the TKI alone group, the TKI plus TRT group achieved significantly better PFS (hazard ratio [HR], 0.57; P = .004) and OS (HR, 0.62; P = .029). The median PFS was 10.6 months in the TKI alone group and 17.1 months in the TKI plus TRT group. The median OS was 26.2 months and 34.4 months in the TKI alone group and TKI plus TRT group, respectively. The TKI plus TRT group showed better local control but was associated with a higher incidence of severe TRAEs (11.9% v 5.1%).

CONCLUSION

For patients with EGFR-mutated oligo-organ metastatic NSCLC treated with first-line EGFR-TKIs, concurrent TRT improves the PFS and OS, and TRAEs are acceptable and tolerable.

Predictors of brain metastases in patients with oligometastatic solid tumours treated with stereotactic body radiation therapy

PURPOSE

In patients with oligometastatic disease (OMD) treated with stereotactic body radiation therapy (SBRT), those who develop brain metastases (BrM) may have poor outcomes. We aimed to investigate variables associated with BrM development in this population.

METHODS

Patients with ≤ 5 extracranial metastases from solid tumors treated with SBRT from 2008 to 2016 at Sunnybrook Odette Cancer Centre were included. We investigated the association between covariates and CIBrM (cumulative incidence of BrM) using Fine-Gray analysis, and progression-free survival (PFS) and overall survival (OS) using Cox regression. We investigated the association between extracranial progression and CIBrM using time-based conditional analysis.

RESULTS

Among 404 patients, the most common primary sites were lung, colorectal, prostate, breast and kidney. Median follow-up was 49 months. Median PFS was 25 months. Median OS was 70 months. 58 patients developed BrM, and 5-year CIBrM was 16%. On multivariable analysis, number of extracranial metastases, location of metastases, total planning target volume (PTV), and time from primary diagnosis to OMD were not associated with CIBrM, although several of these variables were associated with extracranial PFS and OS. Primary site was associated with CIBrM, with colorectal and prostate cancer associated with lower CIBrM compared to lung cancer. Widespread extracranial progression (≥ 5 sites) within 24, 36, 48 and 60 months of OMD diagnosis was independently associated with higher CIBrM.

CONCLUSION

In patients with OMD treated with SBRT, baseline variables related to extracranial disease burden and distribution were not associated with BrM development, while primary site and widespread extracranial progression were associated with BrM development.

Radiotherapy Improves Survival in NSCLC After Oligoprogression on Immunotherapy: A Cohort Study

Introduction

The patterns of oligoprogression after first-line immune checkpoint inhibitors (ICIs) for metastatic NSCLC are yet to be well established. An increasing volume of data suggests that directed radiotherapy improves survival outcomes in patients with progression after ICIs.

Methods

A retrospective cohort study was performed on patients with metastatic NSCLC who had completed first-line programmed death-(ligand) 1 inhibitor therapy with or without chemotherapy at two high-volume cancer centers. We sought to characterize the frequency and location of oligoprogression and determine the overall survival (OS) after radiotherapy in this population.

Results

A total of 159 patients were included in the study. At first progression, 62 (39.0%) were classified as undergoing oligoprogression. Multivariate analysis confirmed the presence of brain metastases was associated with an increased likelihood of oligoprogression (OR = 2.44, p = 0.04) with most (63.2%) of these patients experiencing progression intracranially. The presence of liver metastases was associated with a decreased likelihood of oligoprogression (OR = 0.17, p < 0.01). For patients with oligoprogression, those who received radiotherapy had a longer median progression-free survival-2 (PFS2) (17 versus 11.5 mo, HR = 0.51, p = 0.02) and a longer median OS (23 versus 13 mo, HR = 0.40, p < 0.001) compared with those who did not receive radiotherapy. No difference in PFS2 or OS outcomes was observed between patients who received radiotherapy versus those who did not for systemic progression.

Conclusions

In patients with oligoprogressive metastatic NSCLC after treatment with first-line ICIs, radiotherapy significantly improves OS and PFS2 outcomes. Patients with baseline brain metastases are more likely to experience oligoprogression. Further prospective studies in directed, less heterogeneous populations of patients with metastatic NSCLC will be fundamental to optimize management.

Tumor reirradiation: Issues, challenges and perspectives for radiobiology

The radiobiology of tumor reirradiation is poorly understood. It pertains to tumors and their sensitivity at the time of relapse, encompassing primary tumors, metastases, or secondary cancers developed in or proximal to previously irradiated tissues. The ability to control the pathology depends, in part, on understanding this sensitivity. To date, literature data remains limited regarding changes in the radiosensitivity of tissues after initial irradiation, and most proposals are based on conjecture. The response of healthy tissues at the site of irradiation raises concerns about radio-induced complications. Cumulative dose is likely a major factor in this risk, thus using equivalent dose calculations might help reduce the risk of complications. However, the correlation between mathematical equivalence formulas and clinical effects of radiobiological origin is weak, and the lack of knowledge of the alpha/beta (α/β) ratio of healthy tissues remains an obstacle to the extensive use of these formulas. However, tissues exposed to recovery dose may have a tolerance to irradiation much higher than assumed, thus further biological work remains to be developed. Also, the functionality of previously irradiated tissues could be useful in selecting the most suitable irradiation beams. Finally, research on the genomics of irradiated healthy tissues could improve the prediction of side effects and personalize radiotherapy.

Acute toxicity in patients with oligometastatic cancer following metastasis-directed stereotactic body radiotherapy: An interim analysis of the E2-RADIatE OligoCare cohort

AIM

To evaluate acute toxicity at 6 months after stereotactic body radiotherapy (SBRT) in patients with oligometastatic cancer within the OligoCare cohort.

MATERIAL AND METHODS

OligoCare is a prospective, registry-based, single-arm, observational study that aims to report prospective real-world data of patients with oligometastases from solid cancer treated with SBRT (NCT03818503). Primary tumor included non-small cell lung cancer (NSCLC), breast cancer (BC), colorectal cancer (CRC), and prostate cancer (PC). This analysis addresses a secondary endpoint of the trial, acute toxicity within 6 months after SBRT.

RESULTS

Out of 1,597registered patients, 1'468 patients were evaluated for acute toxicity. Globally, 290 (20 %) had NSCLC primary disease, 227 (16 %) had BC, 293 (20 %) had CRC, and 658 (45 %) had PC. Concomitant systemic treatment was administered in 527 (35.9 %) patients. According to the EORTC/ESTRO oligometastatic disease (OMD) classification, 828 (56 %) patients had de novo OMD, 464 (32 %) repeat OMD, and 176 (12 %) induced OMD. Acute grade ≥ 3 SBRT related adverse events were reported in 8 (0.5 %) patients, including 2 (0.1 %) fatal AEs. In particular, 6 (0.4 %) grade 3 events were: 1 empyema, 1 pneumonia, 1 radiation pneumonitis, 1 radiation skin injury, 1 decreased appetite, and 1 bone pain. Among those 2 occurred in NSCLC patients, 2 in BC patients, and 1 in CRC and PC patients each. The two (0.1 %) grade 5 toxicity were represented by: pneumonitis and cerebral hemorrhage.

CONCLUSION

OligoCare is the largest prospective registry cohort on oligometastatic disease. Acute toxicity within 6 months was low, confirming the safety of SBRT in the treatment of oligometastases.

Stereotactic body radiotherapy for spinal oligometastases: a survey on patterns of practice on behalf of the Italian Association of Clinical Oncology and Radiotherapy (AIRO)

BACKGROUND

The Study Group for the Biology and Treatment of the OligoMetastatic Disease on behalf of the Italian Association of Radiotherapy and Clinical Oncology (AIRO) has conducted a national survey with the aim to depict the current patterns of practice of stereotactic body radiotherapy (SBRT) for spinal oligometastases.

METHODS

The Surveymonkey platform was used to send a 28-items questionnaire focused on demographic, clinical and technical aspects related to SBRT for spinal oligometastases. All the AIRO members were invited to fill the questionnaire. Data were then centralized to a single center for analysis and interpretation.

RESULTS

53 radiation oncologists from 47 centers fulfilled the survey. A complete agreement was observed in proposing SBRT for spinal oligometastases, with the majority considering up to 3 concurrent spine oligometastases feasible for SBRT (73.5%), regardless of spine site (70%), vertebral segment (85%) and morphological features of the lesion (71.7%). Regarding dose prescription, fractionated regimens resulted as the preferred option, either in 3 (58.4%) or five sessions (34%), with a substantial agreement in applying a PTV-margin larger than 1 mm (almost 90% of participants), and ideally using both MRI and PET imaging to improve target volume and organs-at-risk delineation (67.9%).

CONCLUSIONS

This national italian survey illustrates the patterns of practice and the main issues for the indication of SBRT for spinal oligometastases. A substantial agreement in the numerical cut-off and vertebral segment involved for SBRT indication was reported, with a slight heterogeneity in terms of dose prescription and fractionation schemes.

Stereotactic radiotherapy for liver oligometastases: a pooled analysis following the estro/eortc consensus recommendations

A large pooled analysis of liver oligometastases, classified accordingly to the ESTRO/EORTC recommendations, treated by stereotactic radiotherapy (SBRT) and Radiosurgery (SRS) was carried out. The clinical and dosimetric data of patients who underwent SBRT/SRS for liver metastases were analysed in terms of efficacy and toxicity profile. In particular, the Local Control (LC), the Distant Metastases Free Survival (DMFS), the Disease-Free Survival (DFS), the Overall Survival (OS), and the Next Systemic Therapy Free Survival (NEST-FS) rates were analysed. 113 patients (M/F: 49/64), accounting for a total of 150 hepatic lesions (March 2006-February 2023) in two Italian radiotherapy Institutions were evaluated. Median age was 67 years old (36-92) and 48 (42.5%) patients had at least one comorbidity. The majority of the lesions were induced (30.7%) or repeated oligoprogressive (12.7%) metastases. 98 lesions were treated with more than one daily fraction (mainly 50 Gy in 5 fractions), while 52 were radiosurgery treatments (mainly 32 Gy). The treatment response at 3-4 months was evaluable in 147 lesions: complete response was 32.0%, partial response 17.0%, and stable disease 32.0%. Actuarial LC, DMFS, DFS, OS, and NEST-FS at 1 year were 75.8%, 37.7%, 34.9%, 78.7%, and 59.4% respectively; while actuarial LC, DMFS, DFS, OS, and NEST-FS at 2 years were 52.1%, 24.9%, 21.9%, 51.3%, and 36.8%, respectively. The achievement of complete response, synchronous oligometastases, and no treatment interruptions correlated with a more favorable outcomes. As per the toxicity profile, we registered only two acute and one late toxicity cases higher than grade 2. Stereotactic treatment for liver metastases seems to be a safe and promising option in terms of local control. The best results in term of outcomes have been obtained in patients with complete response, synchronous oligometastases, favorable histology, and no treatment interruptions.

Machine learning predicts conventional imaging metastasis-free survival (MFS) for oligometastatic castration-sensitive prostate cancer (omCSPC) using prostate-specific membrane antigen (PSMA) PET radiomics

PURPOSE

This study investigated imaging biomarkers derived from PSMA-PET acquired pre- and post-metastasis-directed therapy (MDT) to predict 2-year metastasis-free survival (MFS), which provides valuable early response assessment to improve patient outcomes.

MATERIALS/METHODS

An international cohort of 117 oligometastatic castration-sensitive prostate cancer (omCSPC) patients, comprising 34 from John Hopkins Hospital (JHH) and 83 from Baskent University (BU), were treated with stereotactic ablative radiation therapy (SABR) MDT with both pre- and post-MDT PSMA-PET/CT scans acquired. PET radiomic features were analyzed from a CT-PET fusion defined gross tumor volume ((GTV) or zone 1), and a 5 mm expansion ring area outside the GTV (zone 2). A total of 1748 PET radiomic features were extracted from these zones. The six most significant features selected using the Chi2 method, along with five clinical parameters (age, Gleason score, number of total lesions, untreated lesions, and pre-MDT prostate-specific antigen (PSA)) were extracted as inputs to the models. Various machine learning models, including Random Forest, Decision Tree, Support Vector Machine, and Naïve Bayesian, were employed for 2-year MFS prediction and tested using leave-one-out and cross-institution validation.

RESULTS

Six radiomic features, including Total Energy, Entropy, and Standard Deviation from pre-PSMA-PET zone 1, Total Energy and Contrast from post-PSMA-PET zone 1, and Entropy from pre-PSMA-PET zone 2, along with five clinical parameters were selected for predicting 2-year MFS. In a leave-one-out test with all the patients, random forest achieved an accuracy of 80 % and an AUC of 0.82 in predicting 2-year MFS. In cross-institution validation, the model correctly predicted 2-year MFS events with an accuracy of 75 % and an AUC of 0.77 for patients from JHH, and an accuracy of 78 % and an AUC of 0.80 for BU patients, respectively.

CONCLUSION

Our study demonstrated the promise of using pre- and post-MDT PSMA-PET-based imaging biomarkers for MFS prediction for omCSPC patients.

The efficacy of screening with FDG-PET/CT for distant metastases in breast cancer patients scheduled for neoadjuvant systemic therapy

PURPOSE

This study aims to identify which breast cancer patients benefit from the routine use of FDG-PET/CT in a large cohort of patients scheduled for neoadjuvant systemic therapy (NST).

METHODS

A total of 1337 breast cancer patients eligible for NST were identified from a retrospective database between 2011 and 2020 at a single tertiary care hospital. All patients underwent staging with FDG-PET/CT prior to NST. The incidence and extent of asymptomatic distant metastases in different patient subgroups were determined, as well as the impact on treatment. Logistic regression analysis was used to identify prognostic patient and tumor characteristics.

RESULTS

FDG-PET/CT detected distant metastases in 109 patients (8%). Initial clinical stage was a prognostic factor for the presence of distant metastases, with a significantly higher risk for stage 2b and 3 as opposed to lower stages (p < 0.001). The incidence of distant metastases was 3% (4/125) for stage 1, 2% (8/534) for stage 2a, 7% (24/354) for stage 2b and 23% (73/324) for stage 3. Other characteristics such as age, tumor subtype, histological type and grade were not correlated with the risk of distant metastases. Among the subset of patients with distant metastases, 46% received palliative treatment, while the remaining 54% were diagnosed with oligometastatic breast cancer and were treated with curative intent.

CONCLUSION

The results of the current study support the routine use of FDG-PET/CT for the detection of distant metastases in breast cancer patients with initial clinical stage 2b and 3, regardless of tumor subtype.

Oligometastatic non-small cell lung cancer: Impact of local and contemporary systemic treatment approaches on clinical outcome

Oligometastatic (OMD) non-small cell lung cancer (NSCLC) is a distinct but heterogeneous entity. Current guidelines recommend systemic therapy and consolidation with local ablative therapy (LAT). However, evidence regarding the optimal choice of multimodal treatment approaches is lacking, in particular with respect to the integration of immunotherapy. This real-world study identified 218 patients with OMD NSCLC (2004-2023, prespecified criteria: ≤5 metastases in ≤2 organ systems) from three major German comprehensive cancer centers. Most patients had one (72.5%) or two (17.4%) metastatic lesions in a single (89.9%) organ system. Overall survival (OS) was significantly longer with a single metastatic lesion (HR 0.54, p = .003), and female gender (HR 0.4, p < .001). Median OS of the full cohort was 27.8 months, with 29% survival at 5 years. Patients who had completed LAT to all NSCLC sites, typically excluding patients with early progression, had a median OS of 34.4 months (37.7% 5-year OS rate) with a median recurrence-free survival (RFS) of 10.9 months (13.3% at 5 years). In those patients, systemic treatment as part of first-line therapy was associated with doubling of RFS (12.3 vs. 6.4 months, p < .001). Despite limited follow-up of patients receiving chemo-immunotherapy (EU approval 2018/2019), RFS was greatly improved by adding checkpoint inhibitors to chemotherapy (HR 0.44, p = .008, 2-year RFS 51.4% vs. 15.1%). In conclusion, patients with OMD NSCLC benefitted from multimodality approaches integrating systemic therapy and local ablation of all cancer sites. A substantial proportion of patients achieved extended OS, suggesting a potential for cure that can be further augmented with the addition of immunotherapy.

Recent developments in the field of radiotherapy for the management of lung cancer

Lung cancer has a poor prognosis, and further improvements in outcomes are needed. Radiotherapy plays an important role in the treatment of unresectable lung cancer, and there have been recent developments in the field of radiotherapy for the management of lung cancer. However, to date, there have been few reviews on the improvement in treatment outcomes associated with high precision radiotherapy for lung cancer. Thus, this review aimed to summarize the recent developments in radiotherapy techniques and indicate the future directions in the use of radiotherapy for lung cancer. Stereotactic body radiotherapy (SBRT) for unresectable stage I lung cancer has been reported to improve local control rates without severe adverse events, such as radiation pneumonitis. For locally advanced lung cancer, a combination of chemoradiotherapy and adjuvant immune checkpoint inhibitors dramatically improves treatment outcomes, and intensity-modulated radiotherapy (IMRT) enables safer radiation therapy with less frequent pneumonitis. Particle beam therapy, such as carbon-ion radiotherapy and proton beam therapy, has been administered as advanced medical care for patients with lung cancer. Since 2024, it has been covered under insurance for early stage lung cancer with tumors ≤ 5 cm in size in Japan. In addition to chemotherapy, local ablative radiotherapy improves treatment outcomes in patients with oligometastatic stage IV lung cancer. A particular problem with radiotherapy for lung cancer is that the target location changes with respiratory motion, and various physical methods have been used to control respiratory motion. Recently, coronavirus disease has had a major impact on lung cancer treatment, and cancer treatment during situations, such as the coronavirus pandemic, must be performed carefully. To improve treatment outcomes for lung cancer, it is necessary to fully utilize evolving radiotherapy modalities, and the role of radiotherapy in lung cancer treatment is expected to increase.

Prognostic factors after radical local therapy for oligo-recurrence of non-small cell lung cancer

OBJECTIVE

Oligo-recurrence refers to the presence of a limited number of metachronous recurrences that can be treated with radical local therapy, and most patients have a good prognosis. However, the clinical course after local therapy for oligo-recurrence of non-small cell lung cancer (NSCLC) varies, and the prognostic factors are unclear. The aim of this study was to elucidate the prognostic factors of patients with oligo-recurrence of NSCLC who underwent radical local therapy.

METHODS

Between 2004 and 2015, 901 patients who underwent complete resection for NSCLC were included. We defined oligo-recurrence as two or fewer recurrences and retrospectively examined the factors that affected post-recurrence survival in patients who underwent radical local therapy for oligo-recurrence.

RESULTS

Recurrence was confirmed in 267 patients, and among them, 125 experienced oligo-recurrence. Eighty-five patients with oligo-recurrence received local therapy, and their 5-year post-recurrence survival rate was 42.8%. Multivariable analysis of the prognostic factors of these patients revealed that single recurrence (hazard ratio = 2.19, P = 0.005) and systemic therapy (hazard ratio = 1.75, P = 0.043) were significant favorable prognostic factors associated with post-recurrence survival. However, the presence or absence of epidermal growth factor gene mutations, which is generally a prognostic factor for NSCLC recurrence, did not affect the prognosis of these patients.

CONCLUSIONS

The number of recurrences and receiving systemic therapy are important prognostic factors for patients with oligo-recurrence who undergo radical local therapy, and these patients have a particularly favorable prognosis.

Stereotactic Ablative Radiation Therapy for Oligometastatic Ovarian Cancer Lymph Node Disease: The MITO-RT3/RAD Phase II Trial

PURPOSE

MITO-RT3/RAD (NCT04593381) is a prospective multicenter phase 2 trial designed to assess the effectiveness and safety of stereotactic body radiation therapy (SBRT) in patients who received diagnoses of oligometastatic ovarian cancer. In this report, we provide the results of the trial in the setting of lymph node disease.

METHODS AND MATERIALS

The primary endpoint was the complete response (CR) rate, secondary endpoints included local control (LC), progression-free survival (PFS), overall survival, treatment-free interval, and toxicity rates. The sample size was based on a previous study reporting an average 70.0% CR with SBRT. The study was powered to detect an improvement in the CR rate from 70.0% to 85.0%, with an α error of 0.05 (one-side) and a β error of 0.1.

RESULTS

The study met its primary endpoint of a statistically significant improvement in CR. One hundred thirty-five patients with 249 lesions were enrolled across 15 institutions from May 2019 to November 2023. CRs were observed in 194 lesions (77.9%), partial responses in 40 (16.1%), stable disease in 14 (5.6%), and progressive disease in 1 lesion (0.4%). The objective response rate was 94%, with an overall clinical benefit rate of 99.6%. CR lesions exhibited a significantly higher LC rate than partial or not responding lesions (12-month LC: 92.7% vs 63.1%, P < .001). The 12-month actuarial rates for PFS and for overall survival were 36.6% (CR, 38.3% vs not-CR, 18.8%; P, .022) and 97.2% (CR, 97.8% vs not-CR, 93.8%; P, .067), respectively. The 12-month actuarial rate for treatment-free interval was 52.7% (CR, 58.4% vs not-CR, 24.4%; P, .004). CR was substantially associated with higher PFS (P, .036) and treatment-free interval (P, .006) rates in the univariate analysis. Twenty-three patients (17.0%) experienced mild acute toxicity. Late toxicity was reported in 9 patients (6.7%), mostly grade 1.

CONCLUSIONS

This trial confirms the efficacy of ablative SBRT, with minimal toxicity observed. SBRT offered a high CR rate, promising long-term outcomes, and a significant systemic therapy-free survival period for complete responders.

Local treatment for oligoprogressive metastatic sites of breast cancer: efficacy, toxicities and future perspectives

Metastatic breast cancer (MBC) is still an incurable disease, which eventually develops resistance mechanisms against systemic therapies. While most patients experience widespread disease progression during systemic treatment (ST), in some cases, progression may occur at a limited number of metastatic sites. Evidence from other malignancies suggests that local treatment with stereotactic ablative radiotherapy (SABR) of oligoprogressive disease (OPD) may allow effective disease control without the need to modify ST. Available evidence regarding local treatment of oligoprogressive breast cancer is limited, mostly consisting of retrospective studies. The only randomized data come from the randomized CURB trial, which enrolled patients with oligoprogressive disease, including both small cell lung cancer and breast cancer patients, and did not show a survival benefit from local treatment in the latter group. However, local treatment of oligoprogressive MBC is still considered in clinical practice, especially to delay the switch to more toxic STs. This review aims to identify patients who may benefit from this approach based on the current available knowledge, focusing also on the potential risks associated with the combination of radiotherapy (RT) and ST, as well as on possible future scenarios.

The Role of Local Prostate and Metastasis-Directed Radiotherapy in the Treatment of Oligometastatic Prostate Cancer

Background/Objectives: Oligometastatic prostate cancer (OMPC) represents an early stage of metastatic disease characterized by a limited number of lesions. Recent advancements in imaging and treatment have revived interest in personalized therapies, including metastasis-directed radiotherapy (OMDRT) and primary prostate radiotherapy (PPR). This study evaluates the impact of OMDRT timing and the role of PPR on survival outcomes in OMPC patients; Methods: In this retrospective cohort study, 82 patients with OMPC who underwent OMDRT between 2010 and 2019 were analyzed. Patients were classified based on OMDRT timing (early vs. late) and disease type (synchronous vs. metachronous). Progression-free survival (PFS) and overall survival (OS) were the primary endpoints, assessed via Kaplan-Meier analysis and Cox proportional hazards models; Results: Among the patients, 36 (43.9%) had synchronous and 46 (56.1%) had metachronous OMD. With a median follow-up of 32 months, the 5-year PFS and OS rates were 77.5% and 88.5%, respectively. Early OMDRT significantly improved PFS (HR 0.461, 95% CI: 0.257-0.826, p = 0.009) and OS (HR 0.219, 95% CI: 0.080-0.603, p = 0.003). Subgroup analysis showed the most favorable outcomes for synchronous OMD patients receiving early OMDRT, with a median PFS of 22.2 months and a 5-year survival rate of 42.1%. The treatment of the primary prostate provided a survival benefit in the OS of synchronous OMD patients (5-year 83.1% vs. 50%, p = 0.025), and there was a further improvement in OS after PPR (5-year 87.7% vs. 50%, p = 0.015). Conclusions: Early OMDRT significantly enhances survival outcomes in OMPC, in both synchronous and metachronous cases. The integration of PPR can further improve results, emphasizing the importance of early intervention and personalized treatment strategies. To more definitively clarify our findings across various clinical situations, further studies with larger cohorts or prospective designs are necessary.

Recurrent Versus Metastatic Head and Neck Cancer: An Evolving Landscape and the Role of Immunotherapy

Squamous cell carcinoma of the head and neck (SCCHN) is among the ten most common cancers worldwide, with advanced SCCHN presenting with a 5-year survival of 34% in the case of nodal involvement and 8% in the case of metastatic disease. Disease-free survival at 2 years is 67% for stage II and 33% for stage III tumors, whereas 12-30% of patients undergo distant failures after curative treatment. Previous treatments often hinder the success of salvage surgery and/or reirradiation, while the standard of care for the majority of metastatic SCCHN remains palliative chemo- and immuno-therapy, with few patients eligible for locoregional treatments. The aim of this paper is to review the characteristics of recurrent SCCHN, based on different recurrence sites, and metastatic disease; we will also explore the possibilities not only of salvage surgery and reirradiation but also systemic therapy choices and locoregional treatment for metastatic SCCHN.

Focal therapy for oligometastatic and oligoprogressive renal cell carcinoma: a narrative review

Metastatic renal cell carcinoma (RCC) can present with oligometastatic disease and/or develop oligoprogression following systemic therapy. Cytoreductive and focal metastasis-directed therapy options include resection, stereotactic ablative radiation and thermal ablation. Aggressive focal therapy may allow delay in initiation of or modification to systemic therapy and improve clinical outcomes. In this narrative review we synthesize current practice guidelines and prospective data on focal therapy management options and highlight future research. Patient selection and the choice of focal treatment techniques are controversial due to limited and heterogeneous data and patients may benefit from multidisciplinary evaluation. Prospective comparative trials with clearly defined inclusion criteria and relevant end points are needed to clarify the risks and benefits of different approaches.

The Role of Stereotactic Body Radiotherapy in Oligoprogressive Malignant Disease (RADIANT): Oncologic Outcomes From a Phase 2 Nonrandomized Controlled Trial

PURPOSE

In oligoprogressive (OP) cancer, there are a limited number of metastatic areas progressing on a background of stable or responding to widespread cancer. Although the standard of care for OP is changing systemic therapy (ST), stereotactic body radiation therapy (SBRT) is being explored as an alternative local therapy targeting the sites of progression.

METHODS AND MATERIALS

RADIANT (NCT04122469) was a single-center phase 2 study of patients with metastatic genitourinary (GU), breast, and gastrointestinal (GI) cancers, receiving ST for ≥3 months, with radiographic OP disease in ≤5 sites. Patients received SBRT for all OP disease in 1 to 5 fractions and were maintained on ST. The primary endpoint was the cumulative incidence of change in ST, which was estimated using the Aalen-Johansen method. Secondary endpoints included progression-free survival (PFS) and overall survival estimated using the Kaplan-Meier method, as well as toxicity and health-related quality of life. Comparisons between diagnosis groups were done using the log-rank test. A 2-sided p value <.05 was considered statistically significant.

RESULTS

Seventy patients were analyzed, with a median age of 69 years; 32 patients (46%) were women; the median number of lines of prior ST was 3. Primary sites were GU (n = 32; 46%), breast (n = 23; 33%), and GI (n = 15; 21%). The median follow-up was 12.3 months (IQR, 8.2-21.6 months). At 1 year, change in ST occurred in 47% (95% CI, 36%-61%) (GU 45%, breast 41%, and GI 60%; p = .23). PFS at 1 year was 32% (95% CI, 23%-45%), and median PFS was 4.7 months (95% CI, 3.8-8.1) (GU 4.8, breast 6.5, and GI 3.2), which significantly differed by disease type (p = .006). Overall survival was 75% at 1 year (95% CI, 65%-87%), which significantly differed between cancer types (GU 86%, breast 96%, and GI 22%; p < .001). The cumulative incidence of late grade ≥2 toxicity was 1.2%, with 1 patient experiencing late grade 3 toxicity and no grade 4 to 5 acute or late toxicities. Health-related quality of life declined from the mean (SD) of 66.9 (20.2) at baseline to 60.5 (22.2) at 6 months, which did not meet the threshold for a minimal clinically important difference.

CONCLUSIONS

SBRT for OP metastases delayed change in ST in approximately half of patients, warranting investigation in randomized trials.

Stereotactic Body Radiation Therapy for Oligoprogressive Ovarian Cancer Patients Treated During Poly(ADP-Ribose)-Polymerase Inhibitor Maintenance: Efficacy and Adverse Events From the Epimetheo Retrospective Study

PURPOSE

The aim of this observational, retrospective, multicenter study (Epimetheo) was to analyze the activity and the safety of stereotactic body radiation therapy (SBRT) during poly(ADP-ribose)-polymerase inhibitor (PARPi) maintenance in a series of oligometastatic ovarian cancer (OC) patients.

METHODS AND MATERIALS

Patients treated with PARPi in maintenance setting received SBRT if oligometastatic progression occurred. Maintenance treatment was continued until the extensive progression of the disease. The primary endpoints of the study were as follows: next systemic treatment change-free survival (NEST-FS) and acute and late toxicity; the secondary endpoints were as follows: the rate of clinical complete response (CR), the 2-year actuarial local control (LC, progression of disease inside SBRT field) rate on "per lesion" basis, the 2-year actuarial progression-free survival, and 2-year overall survival (OS).

RESULTS

From April 2018 to September 2023, SBRT was used to treat 74 OC patients with a total of 158 lesions (98 lymph nodes and 60 parenchymal lesions) under PARPi maintenance. Olaparib, niraparib, and rucaparib were administered to 41.9%, 48.6%, and 9.5% of patients, respectively. CR, partial response, stable disease, and progressive disease were observed in 115 (72.8%), 32 (20.3%), 9 (5.7%), and 2 lesions (1.3%), respectively. Severe toxicities were reported in less than 3% of patients. The actuarial median NEST-FS was 10 months, with a range of 6.7-13.3 months. The 12- and 24-month actuarial NEST-FS rates were 44.9% and 31.4%, respectively. The 2-year actuarial LC, progression-free survival, and OS were 68.1%, 22.5%, and 77%, respectively with differences in figures between complete and incomplete responders. The achievement of CR was found to be correlated with an improvement in LC and OS.

CONCLUSIONS

This study reports the activity and the low toxicity profile of SBRT in association with PARPi in oligometastatic OC patients. A rapid, minimally invasive, and cost-effective treatment such as SBRT may be proposed as a means of prolonging NEST-FS and maintaining an effective treatment regimen involving PARPi.

Prognostic value of circulating tumor cells in oligorecurrent hormone-sensitive prostate cancer patients undergoing stereotactic body radiation therapy

BACKGROUND

Stereotactic body radiation therapy (SBRT) is an effective metastasis-directed therapy for managing oligometastatic prostate cancer patients. However, it lacks reliable biomarkers for risk stratification. Circulating Tumor Cells (CTC) show promise as minimally invasive prognostic indicators. This study evaluates the prognostic value of CTC in oligorecurrent hormone-sensitive prostate cancer (orHSPC).

METHODS

orHSPC patients with 1-3 nodal and/or bone metastases undergoing SBRT were enrolled (N = 35), with a median follow-up time of 42.1 months. CTC levels were measured at baseline (T0), 1 month (T1), and 3 months (T2) post-SBRT using a novel metabolism-based assay. These levels were correlated with clinical outcomes through Cox-regression and Kaplan-Meier analyses.

RESULTS

Median CTC counts were 5 at T0, 8 at T1, and 5 at T2 with no significant variation over time. Multivariate analysis identified high (≥5/7.5 mL) T0 CTC counts (HR 2.9, 95% CI 1.3-6.5, p = 0.01, median DPFS 29.7 vs. 14.0 months) and having more than one metastasis (HR 3.9, 95% CI 1.8-8.6, p < 0.005, median DPFS 34.1 vs. 10.7 months) as independent predictors of distant progression-free survival (DPFS). CTC assessment successfully stratified patients with a single metastasis (HR 3.4, 95% CI 1.1-10.2, p = 0.03, median DPFS 42.1 vs. 16.7 months), but not those with more than one metastasis. Additionally, a combined score based on CTC levels and the number of metastases effectively stratified patients.

CONCLUSION

The study demonstrates that hypermetabolic CTC could enhance risk stratification in orHSPC patients undergoing SBRT, particularly in patients with limited metastatic burden, potentially identifying patients with indolent disease who are suitable for tailored SBRT interventions.

Radiosurgery Society Case-Based Guide to Stereotactic Body Radiation Therapy for Challenging Cases of Spinal Metastases

PURPOSE

Spinal stereotactic body radiation therapy (SBRT) has become the standard of care in management of patients with limited sites of metastatic disease, radioresistant histologies, painful vertebral metastases with long life expectancy and cases of reirradiation. Our case-based guidelines aim to assist radiation oncologists in the appropriate utilization of SBRT for common, yet challenging, cases of spinal metastases.

METHODS AND MATERIALS

Cases were selected to include scenarios of large volume sacral disease with nerve entrapment, medically inoperable disease abutting the thecal sac, and local failure after prior SBRT. Relevant literature was reviewed, and areas requiring further investigation were discussed to offer a framework for evidence-based clinical practice.

RESULTS

Spinal SBRT can be effectively delivered in challenging cases following multidisciplinary discussion by using a methodical approach to patient selection, appropriate dose selection, and adherence to evidence-based dose constraints.

CONCLUSIONS

The Radiosurgery Society's case-based practice review offers guidance to practicing physicians treating technically challenging SBRT candidate patients with spinal metastases.

Coverage with evidence development program on stereotactic body radiotherapy in Belgium (2013-2019): a nationwide registry-based prospective study

Background

Although stereotactic body radiotherapy (SBRT) was progressively adopted in clinical practice in Belgium, a reimbursement request in 2011 was not granted because of remaining clinical and economic uncertainty. A coverage with evidence development (CED) program on SBRT started in 2013, with the aim to assess clinical and technical patterns-of-care in Belgium and monitor survival per indication, in view of supporting inclusion in the reimbursement system.

Methods

The Belgian National Institute for Health and Disability Insurance (NIHDI) initiated this prospective observational registry. Participating departments, using SBRT in clinical practice, signed the 'NIHDI convention'. Eligible patients had a primary tumour (PT) or oligometastatic disease (OMD). Patient, tumour, and treatment characteristics were collected through an online module of the Belgian Cancer Registry, prerequisite for financing. Five-year overall survival (5YOS) and 30- and 90-days mortality were primary outcomes, derived from vital status information.

Findings

Between 10/2013 and 12/2019, 20 of the 24 accredited radiotherapy departments participated, 6 were academic. Registered cases per department ranged from 21 to 867. Of 5675 registrations analysed, the majority had good performance status and limited number of lesions. Enrolment of PTs remained stable over time, OMDs almost doubled. Peripheral lung lesions dominated in PTs as in OMDs. Other metastases were (para)spinal, 'non-standard' and hepatic. Thirty- and 90-days mortalities remained below 0.5% [95% CI 0.3%-0.8%] respectively 2.1% [95% CI 1.6%-2.7%]. 5YOS varied by indication, primary prostate patients performing best (85%, 95% CI [76%, 96%]), those with liver metastases worst (19%, 95% CI [15%, 24%]). Better OS was observed in academic departments, department size did not significantly impact survival. OMD survival was better in 2018-19.

Interpretation

CED can be used to define patterns-of-care and real-life outcome of innovative radiotherapy. As the observed survival for different indications was in line with outcome in emerging literature, SBRT was included in the Belgian reimbursement system as of January 2020.

Funding

NIHDI financed participating departments per registered case.

Clinical management of oligometastatic cancer: Applying multidisciplinary tumor board recommendations in practice

Aims

Multidisciplinary tumor boards (MDTs) are an integral part of ensuring high-quality, evidence-based and personalized cancer care. In this study, we aimed to evaluate the adherence to and implementation of MDT recommendations in patients with oligometastatic disease (OMD).

Methods

We screened all oncologic positron emission tomography (PET) scans conducted at a single comprehensive cancer center in 2020. Patients were included if they had evidence of imaging-based OMD from a solid organ malignancy on the index scans, had their OMD case discussed at an MDT, and were treated and followed up at the same center. A switch away from the MDT-recommended treatment modalities was classified as a major deviation; non-MDT-mandated adjustments to a recommended treatment modality were coded as minor deviation. Clinical data was obtained via chart review; statistical calculations were computed using the R software.

Results

After review of PET and/or concurrent brain scans, 787 cases of OMD were identified. Thereof, 347 (44.1 %) cases were discussed at MDT, of which 331 (42.1 %) were therapeutically managed and subsequently followed. The three most commonly recommended therapies were systemic therapy (35.6 %), multimodality treatment including definitive local therapy (17.8 %), and radiotherapy (13.9 %). A major deviation was recorded in 16.3 % of cases (most commonly: none of the MDT-recommended treatment modalities were performed: 19 (35.2 %); not all MDT-planned treatment modalities were performed: 12 (22.2 %); and additional treatment modality was performed: 11 (20.3 %). A minor deviation was found in 1.5 % of cases. On multivariable regression, number of distant metastases (n > 1) was associated with a major deviation (OR: 1.85; 95 % CI, 1.0-3.52). Major deviations were associated with a significantly worse OS (p = 0.0034).

Conclusions

Adherence to and implementation of MDT recommendations in OMD patients was generally high (83.7%). Major deviations might be further reduced by more careful and elaborate discussions of OMD patient characteristics s and patient preferences.

A Phase II Trial of Stereotactic Body Radiation Therapy and Androgen Deprivation for Oligometastases in Prostate Cancer (SBRT-SG 05)

PURPOSE

SBRT-Spanish Group-05 (ClinicalTrials.gov.Identifier: NCT02192788) is a collaborative (SBRT-SG, Grupo de Investigación Clínica en Oncología Radioterápica, and Sociedad Española de Oncología Radioterápica) prospective multicenter phase II trial testing stereotactic body radiation therapy (SBRT) and androgen deprivation therapy (ADT) in patients with oligorecurrent prostate cancer.

METHODS AND MATERIALS

Two cohorts of patients with prostate cancer in an oligorecurrent stage (hormone-sensitive in the principal cohort and castration-resistant in the exploratory cohort) were assigned to receive ADT and SBRT for at least 24 months from the time of the enrollment. Concomitant treatment with chemotherapy, abiraterone, or enzalutamide was not allowed. Oncologic outcomes were assessed in both cohorts. Toxicity was prospectively analyzed.

RESULTS

From 2014 to 2019, 81 patients with a total of 126 lesions from 14 centers met the inclusion criteria, 14 of whom were castration-resistant. With a median follow-up of 40 months (12-58 months), 3-year local recurrence-free survival was 92.5% (95% CI, 79.9%-96.3%) and 85.7% (95% CI, 48.2%-95.6%) in the principal and exploratory cohorts, respectively. In the principal cohort, biochemical relapse-free survival and metastasis progression-free survival at 1, 2, and 3 years were 91% (95% CI, 81%-95.8%), 73.7% (95% CI, 61.1%-82.8%), 50.6% (95% CI, 36.2%-63.3%), and 92% (95% CI, 83%-97%), 81% (95% CI, 70%-89%), and 67% (95% CI, 53%-77%), respectively. In the exploratory cohort, metastasis progression-free survival at 1, 2, and 3 years was 64% (95% CI, 34%-83%), 43% (95% CI, 18%-66%), and 26% (95% CI, 7%-51%), respectively. None of the patients developed grade III or higher toxicity or symptoms related to local progression, and only 2 (2.4%) patients developed grade II toxicity.

CONCLUSIONS

The combination of SBRT and ADT is safe and shows favorable clinical outcomes in patients with hormone-sensitive and castration-resistant prostate cancer. Validation studies are needed in patients with castration-resistant prostate cancer.

Predictive Factors for Long-Term Disease Control in Systemic Treatment-Naïve Oligorecurrent Renal Cell Carcinoma Treated with Up-Front Stereotactic Ablative Radiotherapy (SABR)

BACKGROUND

Stereotactic ablative radiotherapy (SABR) is emerging as a potential local treatment option for oligometastatic RCC. This study aims to evaluate the efficacy of SABR in patients with oligorecurrent RCC.

METHODS

A total of 50 patients with histologically confirmed RCC underwent SABR for oligorecurrence between 2006 and 2022. Eligible patients had up to five extracranial metastases and were systemic treatment-naïve at the time of irradiation. The primary endpoints of the analysis were overall survival (OS), local control (LC), distant metastasis-free survival (DMFS), and time to systemic therapy initiation.

RESULTS

The median OS was not reached, with 1- and 3-year OS rates of 93.8% and 77.5%, respectively. LC rates at one and three years were 95.8% and 86.5%, respectively. The median time to systemic therapy initiation was 63.8 months, and the median DMFS was 17.9 months, with one- and three-year rates of 63.4% and 36.6%, respectively. Multiple metastases were a negative predictive factor for DMFS (HR 2.39, p = 0.023), whereas lung metastases were associated with a more favorable outcome (HR 0.38, p = 0.011).

CONCLUSIONS

SABR offers a valuable treatment option for oligometastatic RCC, demonstrating significant potential for achieving long-term disease control and delaying the need for systemic therapy.

Unraveling the role of local ablative therapies for patients with metastatic soft tissue sarcoma - A retrospective multicenter study of the Bavarian university hospitals

BACKGROUND

Local ablative therapies (LAT) are increasingly used in patients with metastatic soft tissue sarcoma (STS), yet evidence-based standards are lacking. This study aimed to assess the impact of LAT on survival of metastatic STS patients and to identify prognostic factors.

METHODS

In this retrospective multicenter study, 246 STS patients with metastatic disease who underwent LAT on tumor board recommendation between 2017 and 2021 were analyzed. A mixed effects model was applied to evaluate multiple survival events per patient.

RESULTS

Median overall survival (OS) after first metastasis was 5.4 years with 1-, 2- and 5-year survival rates of 93.7, 81.7, and 53.1 %, respectively. A treatment-free interval ≥12 months and treatment of liver metastases were positively correlated with progression-free survival (PFS) after LAT (HR = 0.61, p = 0.00032 and HR = 0.52, p = 0.0081, respectively). A treatment-free interval ≥12 months and treatment of metastatic lesions in a single organ site other than lung and liver were positive prognostic factors for OS after first LAT (HR = 0.50, p = 0.028 and HR = 0.40, p = 0.026, respectively) while rare histotypes and LAT other than surgery and radiotherapy were negatively associated with OS after first LAT (HR = 2.56, p = 0.020 and HR = 3.87, p = 0.025). Additional systemic therapy was independently associated with a PFS benefit in patients ≤60 years with ≥4 metastatic lesions (for max. diameter of treated lesions ≤2 cm: HR = 0.32, p = 0.02 and >2 cm: HR = 0.20, p = 0.0011, respectively).

CONCLUSION

This multicenter study conducted at six German university hospitals underlines the value of LAT in metastatic STS. The exceptionally high survival rates are likely to be associated with patient selection and treatment in specialized sarcoma centers.

The Treatment of Metastatic Renal Cell Carcinoma

BACKGROUND

Approximately 15 000 people receive a diagnosis of renal cell carcinoma (RCC) in Germany each year; in 20-30% of cases, metastatic RCC (mRCC) is already present at the time of diagnosis. This disease in the metastatic stage is still mainly treated palliatively, yet the multimodal therapeutic landscape has changed markedly over the past 15 years, with the approval of many new treatments for patients with mRCC.

METHODS

This review is based on prospective studies retrieved by a selective search in PubMed and the ASCO and ESMO databases and on the German and European oncological and urological guidelines for RCC.

RESULTS

Drugs are the mainstay of treatment. mRCC can be treated with a combination of two immune checkpoint inhibitors (CPIs), a CPI and a tyrosine-kinase inhibitor (TKI) (evidence level IA), or a TKI as monotherapy (evidence level IIC-IC). With prognosis-based sequential drug treatment, a mean progressionfree survival of 12 to 24 months and an overall survival of approximately 50 months can be achieved from the time of initiation of first-line therapy. Aside from pharmacotherapy, the multidisciplinary tumor board should evaluate the indications for local treatments such as cytoreductive nephrectomy, metastasectomy, and radiotherapy, depending on the individual prognostic constellation and the patient's present condition.

CONCLUSION

Optimal individualized decisions require a high level of expertise and the collabo - ration of a multidisciplinary tumor board. Older prognostic parameters currently play a leading role in decision-making, while predictive parameters and molecular markers are not yet adequately validated.

Challenges and Opportunities in Developing an Oncology Clinical Trial Network in the United States Veterans Affairs Health Care System: The VA STARPORT Experience

The United States Veterans Affairs (VA) Health Care System has a strong history of conducting impactful oncology randomized clinical trials (RCTs). We developed a phase II/III RCT to test the use of metastasis-directed therapy in Veterans with oligometastatic prostate cancer (OMPC)-the first VA RCT in OMPC that leverages novel imaging and advanced radiotherapy techniques. To accomplish this, we developed a clinical trial network to conduct the study. In this manuscript, we describe several challenges we encountered in study development/conduct and our strategies to address them, with the goal of helping investigators establish robust study networks to conduct clinical trials. In the study start-up, we encountered challenges in timely site activation, and leveraged project management to maximize efficiency. Additionally, there were several changes in the clinical paradigms in imaging and treatment that led to protocol amendments to ensure maximum equipoise, recruitment, and impact of the study. Specifically, we amended the trial to add de novo OMPC patients (from initially only recurrent OMPC) and expanded the study to allow up to 10 metastases (from initially five). Finally, in order to maintain local study team engagement, we developed initiatives to maximize collaboration and add value to the overall clinical program through study participation.

Is Local Ablative Stereotactic Radiation Therapy a Valuable Rescue Strategy for Time on Drug in Patients Enrolled in Phase I Trials?

PURPOSE

Patients with advanced tumors enrolled in phase I trials display strong treatment expectations and few therapeutic alternatives. When oligoacquired resistance (OAR; ≤3 lesions of disease progression) occurs, local ablative stereotactic radiation therapy (SRT) could allow disease control and continuing the experimental systemic treatment.

METHODS AND MATERIALS

Data from patients enrolled in phase I trials evaluating systemic treatments, who experienced OAR while on the phase I systemic therapy and subsequently received SRT between January 2014 and April 2023, were retrospectively analyzed. Progression-free survival (PFS)1 (trial entry to OAR), PFS2 (SRT to first subsequent relapse), time to next systemic treatment (TTNT), and overall survival (OS) were assessed. First subsequent patterns of relapse after SRT were distinguished as OAR2, which could be locally rechallenged, or systemic acquired resistance (SAR; >3 lesions of disease progression). When available, correlations between molecular profile and pathway enrichments of OAR and SAR were explored.

RESULTS

Forty-two patients with 52 oligoprogressive lesions were analyzed. The median follow-up was 24 months. SRT allowed a median PFS2 of 7.1 months and a median TTNT of 12.8 months. PFS2 included 49% OAR2 and 51% SAR. Median time to first subsequent relapse (9.6 vs 3.5 months; P = .014) and TTNT (22.4 vs 7.6 months; P < .001) were longer for OAR2 compared with that for SAR. No severe toxicities were reported. A PFS1 of <6 months and de novo oligoprogressive lesions were associated with the presence of SAR. More diverse enriched gene pathways were observed for SAR compared with that for OAR2.

CONCLUSIONS

In patients enrolled in phase I trials, OAR managed with SRT may increase time on investigational systemic treatments. Predictive factors reflecting tumor aggressiveness and clonal heterogeneity could help deciphering OAR2 from SAR and maximize SRT output in the oligoprogressive setting.

Outcomes Analysis of Patients Receiving Local Ablative Therapy for Oligoprogressive Metastatic NSCLC Under First-Line Immunotherapy

CONTEXT

Nonsmall Cell Lung Cancer (NSCLC) treatment relies on first-line immunotherapy as single agent or combined with chemotherapy. Oligoprogression may be observed in this setting.

MATERIAL AND METHOD

We performed a European multicentric retrospective study on patients treated with first-line immunotherapy, who presented with oligoprogressive disease, treated with a local ablative treatment.

RESULTS

A total of 61 patients were retrospectively included between 2018 and 2022. Twenty-four patients (39%) received immunotherapy as single agent, and 37 (61%) chemo-immunotherapy. First oligoprogression occurred more frequently in pre-existing metastatic sites (47% of patients). Median PFS1 (defined as time to first oligoprogression) was 11.5 months [IC95%: 10.0-12.3]. We observed that 37 patients (61%) progressed after first oligoprogression, and 20 (54%) from them presented second oligoprogression. Median OS for the whole cohort was 72.0 months [IC95%: 19.3-124.8], with positive correlation between OS and PFS1 (R=0.65, P < .0001). After loco-ablative treatment with radiotherapy, disease control rate was 89% with ablative radiotherapy: 88% with conventional radiotherapy, and 89% with stereotactic radiotherapy.

CONCLUSION

Patients with oligoprogression under/after immunotherapy have better prognosis with a high risk of subsequent oligoprogression.

Addition of Metastasis-Directed Therapy to Systemic Therapy for Oligometastatic Pancreatic Ductal Adenocarcinoma (EXTEND): A Multicenter, Randomized Phase II Trial

PURPOSE

The EXTEND trial tested the hypothesis that adding comprehensive metastasis-directed therapy (MDT) to chemotherapy would improve progression-free survival (PFS) over chemotherapy alone among patients with oligometastatic pancreatic ductal adenocarcinoma (PDAC).

METHODS

EXTEND (ClinicalTrials.gov identifier: NCT03599765) is a multicenter, phase II basket trial randomly assigning patients with ≤five metastases 1:1 to MDT plus systemic therapy versus systemic therapy. Disease progression was defined by radiologic criteria (RECIST v1.1), clinical progression, or death. The primary end point was PFS in the per-protocol population, evaluated after all patients achieved at least 6 months of follow-up. Exploratory end points included systemic immune response measures.

RESULTS

Between March 19, 2019, and February 13, 2023, 41 patients were randomly assigned and 40 were eligible for the primary analysis of PFS (19 patients in the MDT arm; 21 patients in the control arm). At a median follow-up time of 17 months, the median PFS time was 10.3 months (95% CI, 4.6 to 14.0) in the MDT arm versus 2.5 months (95% CI, 1.7 to 5.1) in the control arm. PFS was significantly improved by the addition of MDT to systemic therapy (P = .030 for stratified log-rank test) with a hazard ratio of 0.43 (95% CI, 0.20 to 0.94). No grade ≥3 or greater adverse events related to MDT were observed. Systemic immune activation events were associated with MDT and correlated with improved PFS.

CONCLUSION

This study supports the addition of MDT to systemic therapy for patients with oligometastatic PDAC. Induction of systemic immunity is a possible mechanism of benefit. These results warrant confirmatory trials to refine treatment strategy and provide external validation.

Comparison of the Long-term Survival Outcome of Surgery versus Stereotactic Body Radiation Therapy as Initial Local Treatment for Pulmonary Oligometastases from Colorectal Cancer: A Propensity Score Analysis

PURPOSE

Optimal local treatment for pulmonary oligometastases from colorectal cancer (CRC) remains unclear. We aimed to compare the long-term survival outcomes between surgery and stereotactic body radiation therapy (SBRT) as the initial local treatment for CRC pulmonary oligometastases.

MATERIALS AND METHODS

We retrospectively reviewed 335 consecutive patients who initially underwent surgery or SBRT for CRC pulmonary metastases from 2011 to 2022, and 251 patients (173 surgery and 78 SBRT) were ultimately included. Freedom from intrathoracic progression (FFIP), progression-free survival (PFS), and overall survival (OS) were compared using stabilized inverse probability of treatment weighting (sIPTW) analysis. In addition, patterns of intrathoracic progression and subsequent treatment were analyzed.

RESULTS

Median follow-up was 61.6 months for surgery and 54.4 months for SBRT. After sIPTW adjustment, significant differences emerged in both FFIP and PFS between surgery and SBRT (FFIP: hazard ratio [HR] = 0.50, 95% confidence interval [CI], 0.31-0.79; PFS: HR = 0.56, 95% CI, 0.36-0.87). The 3- and 5-year FFIP rates were 58.6% and 54.8%, respectively, after surgery, and 34.6% and 31.3%, respectively, after SBRT (P = .006). The 3- and 5-year PFS rates were 49.4% and 45.2%, respectively, after surgery, and 28.8% and 26.1%, respectively, after SBRT (P = .010). However, OS was not significantly affected by treatment approach (HR = 0.93, 95% CI, 0.49-1.76). The 3- and 5-year OS rates were 85.9% and 73.1%, respectively, after surgery, and 78.9% and 68.7%, respectively, after SBRT (P = .849). Recurrence at the treated site was more prevalent after SBRT than after surgery (33.3% vs 16.9%), whereas new intrathoracic tumors occurred more frequently after surgery than after SBRT (71.8% vs 43.1%). Both groups chose radiation therapy as the primary local salvage treatment.

CONCLUSIONS

Notwithstanding the significant differences in FFIP and PFS between surgery and SBRT, the long-term survival of patients with CRC pulmonary oligometastases did not depend on the initial choice of the local treatment approach.

Associations amongst genes, molecules, cells, and organs in breast cancer metastasis

This paper is a cross fertilization of ideas about the importance of molecular aspects of breast cancer metastasis by basic scientists, a pathologist, and clinical oncologists at the Henry Ford Health symposium. We address four major topics: (i) the complex roles of lymphatic endothelial cells and the molecules that stimulate them to enhance lymph node and systemic metastasis and influence the anti-tumor immunity that might inhibit metastasis; (ii) the interaction of molecules and cells when breast cancer spreads to bone, and how bone metastases may themselves spread to internal viscera; (iii) how molecular expression and morphologic subtypes of breast cancer assist clinicians in determining which patients to treat with more or less aggressive therapies; (iv) how the outcomes of patients with oligometastases in breast cancer are different from those with multiple metastases and how that could justify the aggressive treatment of these patients with the hope of cure.

Setting-up a training programme for intraoperative molecular imaging and sentinel node mapping: how to teach? How to learn?

BACKGROUND

The current expansion of image-guided surgery is closely related to the role played by radio-guided surgery in supporting the sentinel node (SN) procedure during more than three decades. The so-called triple approach (lymphoscintigraphy, gamma probe detection and blue dye) was not only essential in the seminal validation of the SN procedure but also a first collective learning effort based on skill transfer and outcome-related evaluation which laid the fundaments to delineate the field of intraoperative molecular imaging (IMI) based on a similar multimodality approach and multidisciplinary practice.

METHODS

These elements are also becoming valid in the current incorporation of SPECT/CT and PET/CT to existing and new protocols of IMI procedures and SN mapping concerning other clinical applications. On the other hand, there is a growing tendency to combine novel modern technologies in an allied role with gamma guidance in the operating room following the development of hybrid tracers and multimodal detection approaches. Against this background, learning initiatives are required for professionals working in this area.

RESULTS

This objective has led to a group of European practitioners with large experience in SN mapping and IMI applications to give shape to a programme made up out of specific learning modules aimed to be used as a conductive thread in peripherical or centralised training instances concerning the topic.

CONCLUSION

The presented work, written as a tutorial review, is placed in an available prior-art context and is primarily aimed at medical and paramedical practitioners as well as at hardware and software developers.

The relationship between the treatment course and prognosis of oligometastasis after esophageal squamous cell carcinoma resection

PURPOSE

The concept of oligometastasis, which represents limited metastatic disease, has recently gained interest, accompanied by a more detailed classification. This study aims to investigate the relationship between the treatment course and prognosis in patients with a recurrence of esophageal squamous cell carcinoma (ESCC) after curative esophagectomy.

METHODS

126 patients with ESCC recurrence after curative resection were enrolled in this study. Oligometastasis was defined as fewer than five recurrences in a single organ. Patients were classified as having oligometastatic recurrence (OLR) or polymetastatic recurrence (PLR). Patients were further classified into four subgroups according to lesion progression: persistent oligorecurrence (PER-OLR), converted polyrecurrence (CON-PLR), induced oligorecurrence (IND-OLR), and persistent polyrecurrence (PER-PLR). We analyzed the relationship between the recurrence patterns and prognosis according to the progression of oligometastatic lesions.

RESULTS

OLR was identified in 58 (46%) of 126 patients with recurrence. Patients with OLR had a significantly better prognosis than those with PLR (P < 0.0001). A further subgroup analysis revealed that patients who underwent IND-OLR had a similar prognosis to those who underwent PER-OLR.

CONCLUSIONS

This study suggests that OLR is a prognostic factor after recurrence following resection of ESCC and that PLR can be converted to OLR by therapeutic intervention to achieve a long-term survival.

Outcomes of Radiotherapy in Oligoprogressive Breast Cancer

INTRODUCTION

Radiotherapy (RT) shows potential for improving local control in cases of oligoprogressive metastatic breast cancer (mBC). This retrospective analysis aims to evaluate the advantages of RT in such a clinical scenario.

METHODS

We conducted a retrospective analysis including patients with mBC who received radiation therapy (RT) for up to three sites of oligoprogression while continuing systemic therapy. The study took place between January 2014 and December 2021. Our endpoints were progression-free survival after radiotherapy (PFS-AR), the rate of discontinuation of systemic therapy (RDT) at three months post-RT, and overall survival (OS). We used Cox regression analysis to perform multivariate analysis for PFS-AR.

RESULTS

Fifty-nine patients met the inclusion criteria. The PFS-AR was 13 months (95% CI 8.5-18.8 months). At three months, the RDT was 3% (two patients). A significant difference in median PFS-AR was observed between patients in the first + second-line group and those in the subsequent line group (p = 0.03). In the multivariate analysis conducted for PFS-AR, the biologically effective dose (BED) with α/β = 4 > 100 Gy emerged as the sole significant variable (p = 0.0017). The median overall survival (OS) was 24.4 months (95% CI 17-24.4 months).

CONCLUSIONS

This study is the first report on the outcomes of radiotherapy in a cohort of over 50 patients with oligoprogressive metastatic breast cancer (mBC). Our findings emphasize the significant relationship between PFS-AR, the number of ongoing lines of systemic therapy, and the BED of radiotherapy.