Clinical and molecular markers of long-term survival after oligometastasis-directed stereotactic body radiotherapy (SBRT)

Stereotactic Body Radiation Therapy Alone or in Combination with Immunotherapy in Kidney Cancer: A Systematic Review

BACKGROUND AND OBJECTIVE

Despite its radioresistant reputation, renal cell carcinoma (RCC) is sensitive to high dose per fraction stereotactic ablative body radiotherapy (SABR). As SABR also triggers immunomodulatory effects, a combination of SABR and immunotherapy for RCC might improve patient outcomes. The current systematic review will discuss all prospective studies on SABR alone or combined with immunotherapy.

METHODS

A systematic review was conducted in January 2025 according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement on the PubMed and Cochrane databases. Thirty-eight studies were included in this review.

KEY FINDINGS AND LIMITATIONS

In the primary setting, 15 prospective studies have proved SABR to be a valuable alternative for (partial) nephrectomy for high-risk or medically inoperable patients, with good tolerability and excellent local control. No prospective studies have reported on SABR combined with immunotherapy in nonmetastatic patients. In the oligometastatic setting, two phase 2 trials have investigated SABR in lieu of systemic treatment. This showed encouraging results, with the majority of patients being free from systemic therapy at 1 yr. SABR combined with immunotherapy in the metastatic setting has been investigated in multiple phase 1 and 2 trials, where the most promising option seems to be SABR to multiple-preferentially all-lesions. Cytoreductive SABR and SABR to oligoprogressive lesions combined with immunotherapy are attractive future strategies.

CONCLUSIONS AND CLINICAL IMPLICATIONS

SABR is a valid alternative in localised RCC when (partial) nephrectomy is not an option. In the metastatic setting, several early-phase trials have investigated SABR alone and in combination with immunotherapy, warranting future large, randomised trials.

Single-arm multicenter phase II study on aggressive local consolidative therapy in combination with systemic chemotherapy for stage IV non-small cell lung carcinoma with oligometastases: CURE-OLIGO (TORG1529)

INTRODUCTION

Stage IV non-small cell lung carcinoma (NSCLC) with oligometastases is potentially curable by radical treatment. This study aimed to evaluate the efficacy and safety of chemoradiotherapy (CRT) for thoracic disease, including the primary lesion and lymph node metastases, combined with local consolidative therapy (LCT) for oligometastases.

METHODS

This was a multicenter Phase II trial for patients with Stage IV NSCLC with oligometastases for whom CRT for thoracic disease was feasible. The treatment procedures included CRT containing platinum-doublet for thoracic disease and LCT for oligometastases within 8 weeks of starting or completing CRT. The primary endpoint was the 2-year survival rate.

RESULTS

We enrolled 19 patients between June 2016 and May 2020. The median age was 68 (range: 51-74) years. Twelve patients had adenocarcinoma, and 6 had squamous cell carcinoma. The metastasis sites included the brain, bone, adrenal gland, lung, and cervical lymph node (n = 9, 7, 2, 1, and 1, respectively). All patients completed CRT concurrently with LCT for all oligometastases. There were 11 partial responses, resulting in a response rate of 58% (95% confidence interval [CI] 33.5-79.7%). Median progression-free survival and overall survival were 8.6 (95% CI 7.0-10.2) and 42.1 (80% CI 13.6-not reached) months, respectively. The 2-year survival rate was 68.4% (80% CI 52.6%-79.9%). Fourteen patients (74%) showed progression with newly observed lesions. There were no severe adverse events, and toxicities were tolerable.

CONCLUSION

Chemotherapy in combination with aggressive LCT for NSCLC with oligometastases might extend survival and achieve local control.

CLINICAL TRIAL REGISTRATION

University Hospital Medical Information Network, Japan (protocol identification number: UMIN000022431, first registration date: 01/JUN/2016).

Prognostic and Predictive Biomarkers of Oligometastatic NSCLC: New Insights and Clinical Applications

This review discusses the current data on predictive and prognostic biomarkers in oligometastatic NSCLC and discusses whether biomarkers identified in other stages and widespread metastatic disease can be extrapolated to the oligometastatic disease (OMD) setting. Research is underway to explore the prognostic and predictive value of biological attributes of tumor tissue, circulating cells, the tumor microenvironment, and imaging findings as biomarkers of oligometastatic NSCLC. Biomarkers that help define true OMD and predict outcomes are needed for patient selection for oligometastatic treatment, and to avoid futile treatments in patients that will not benefit from locoregional treatment. Nevertheless, these biomarkers are still in the early stages of development and lack prospective validation in clinical trials. Furthermore, the absence of a clear definition of OMD contributes to a heterogeneous study population in which different types of OMD are mixed and treatment strategies are different. Multiple tissue-based, circulating, and imaging features are promising regarding their prognostic and predictive role in NSCLC, but data is still limited and might be biased owing to the inclusion of heterogeneous patient populations. Larger homogeneous and prospective series are needed to assess the prognostic and predictive role of these biomarkers. As obtaining tissue can be difficult and is invasive, the most promising tools for further evaluation are liquid biopsies and imaging-based biomarkers as these can also be used for longitudinal follow-up.

Treatment of metastatic breast cancer by stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS)

BACKGROUND AND PURPOSE

The role of local ablative radiotherapy (stereotactic body radiotherapy (SBRT)/stereotactic radiosurgery (SRS)) in the management of metastatic breast cancer (mBC) patients remains unclear. This study aimed to assess the efficacy of SBRT/SRS in oligometastatic and oligoprogressive breast cancer patients.

METHODS

Totally 80 mBC patients with oligometastatic disease (OMD) and 80 with oligoprogressive disease (OPD) to ≤5 metastatic lesions were retrospectively analyzed. The endpoint was overall survival and progression-free survival, and univariate and multivariate analyses were performed for survival analysis.

RESULTS

Totally 160 mBC cases (80 OMD and 80 OPD cases) were analyzed, with a total of 291 treated metastases. In the study of OMD, we analyzed 30 cases with oligo-recurrence and 50 cases with sync-oligometastases. The median follow-up time was 46 months, and 1-, 2-, and 3-year OS rates for all patients were 89.8%, 77.6%, and 67.3%, respectively, and the 1-, 2-, and 3-year PFS rates were 71.4%, 44.9%, and 34.7% respectively. In multivariate analysis (MVA), treatment for oligometastases and non-triple-negative status predicted favorable OS. In patients with oligometastases, median OS was 58 months, and 1-, 2-, and 3-year OS rates were 100%, 91.7%, and 83.3%, respectively; median OS in patients with oligoprogression was 35 months, and 1-, 2-, and 3-year OS rates were 80%, 64%, and 52%, respectively. In mBC cases with limited brain metastases administered SRS, poor OS was detected in patient age under 45 years (P = 0.041), triple-negative cases (P = 0.025), and those with OPD (P = 0.022). In OMD, a significant improvement in PFS was observed in the oligo-recurrence group compared to the sync-oligometastases group (P = 0.013).

CONCLUSION

Patients administered local ablative radiotherapy (SBRT/SRS) for oligometastases have better overall survival than those treated for oligoprogression. SBRT/SRS may be beneficial for young and non-triple-negative mBC cases. The presence of oligo-recurrence can predict a favorable prognosis of oligometastases in patients with mBC treated with SBRT/SRS.

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.

Survival Benefit of Synchronous Lenvatinib Combined PD-1 Inhibitors for Advanced Hepatocellular Carcinoma Beyond Oligometastasis

Purpose

Strategies therapy for hepatocellular carcinoma (HCC) beyond oligometastasis are limited. The optimal sequence of systemic treatment for advanced HCC is not yet clear. Our study aims to evaluate the effectiveness of simultaneous lenvatinib combined PD-1 inhibitor on advanced HCC beyond oligometastasis.

Patients and Methods

A total of 232 patients were enrolled in our retrospective study. Patients divided into three groups. (a) Lenvatinib plus simultaneous PD-1 inhibitor (Simultaneous group, n=58); (b) patients received PD-1 inhibitor before the tumor progression with continued lenvatinib administration (Before PD group, n=77); (c) patients received PD-1 inhibitor after the tumor progression (After PD group, n=97). To analyze overall survival (OS) and progression-free survival (PFS) among the three groups.

Results

The estimated 6-, 12-, 18- and 24-mon OS for Simultaneous group patients were 100%, 93.1%, 63.4%, 48.3%, whereas the OS rates were 100%, 78%, 36.3%, 23.6% in Before PD group, and 99%, 61.2%, 22.1%, 7.5% in After PD group. The OS rates were obviously improved with the use of simultaneous PD-1 inhibitor among the three groups (P <0.001). The estimated 3-, 6-, 9- and 12-month PFS rates for patients were 89.6%, 44.8%, 24.6%, 6% in After PD group, 90.9%, 59.7%, 27.3%, 12.4% in Before PD group and 98.3%, 81%, 51.7%, 39.7% in Simultaneous group, respectively. PFS rate was significantly different among the three groups (P <0.001).

Conclusion

Synchronous administration of lenvatinib and PD-1 inhibitors improved survival rate significantly. The synchronous combination could represent a promising strategy in HCC beyond oligometastasis.

SBRT in Lymph-Nodal Oligometastases from Prostate Cancer: Different Outcomes between Pelvic and Para-Aortic Disease

Background: Lymph-nodal prostate cancer oligometastases are differently treated according to their site: pelvic are locoregional lymph nodes; instead, para-aortic lymph nodes are considered as distant metastases. The aim of the study was a comparison between para-aortic and pelvic oligometastases treated with stereotactic body radiation therapy (SBRT). Methods: This is a retrospective analysis. De novo metastatic or extra-nodal disease were excluded. Univariate and multivariate analyses were performed; the pattern of recurrence was also evaluated. A propensity score matching (PSM) was applied to create comparable cohorts. The primary end-point was the progression-free survival (PFS). The secondary end-points were biochemical relapse-free survival (BRFS), ADT-free survival (ADTFS), polymetastases-free survival (PMFS), local progression-free survival (LPFS), and pattern of relapse. Results: In total, 240 lymph-nodal oligometastases in 164 patients (127 pelvic and 37 para-aortic) were treated. The median PFS was 20 and 11 months in pelvic and para-aortic patients, respectively (p = 0.042). The difference was not confirmed in the multivariate analysis (p = 0.06). The median BRFS was 16 and 9 months, respectively, in the pelvic and para-aortic group (p = 0.07). No statistically significant differences for ADTFS or PMFS were detected. The cumulative 5-year LPFS was 90.5%. In PSM, no statistically significant differences for all the study end-points were detected. Conclusions: Patients affected by para-aortic disease might have a PFS comparable to pelvic disease; local control is high in both cohorts. Our results also support the use of SBRT for para-aortic metastases.

Definitive results of a prospective non-randomized phase 2 study on stereotactic body radiation therapy (sbrt) for medically inoperable lung and liver oligometastases from breast cancer

BACKGROUND AND PURPOSE

To report mature results for local control and survival in oligometastatic (OM) breast cancer patients treated with stereotactic body radiotherapy (SBRT) on lung and/or liver lesions in a phase II trial.

METHODS

This is a prospective non-randomized phase II trial (NCT02581670) which enrolled patients from 2015 to 2021. Eligibility criteria included: age > 18 years, ECOG 0-2, diagnosis of breast cancer, maximum of 4 lung/liver lesions (with a maximum diameter < 5 cm), metastatic disease confined to the lungs and liver or extrapulmonary or extrahepatic disease stable or responding to systemic therapy. The primary end-points were local control (LC) and treatment-related toxicities. The secondary end-points included overall survival (OS), distant metastasis-free survival (DMFS), time to next systemic therapy (TTNS), poly-progression free survival (PPFS).

RESULTS

The study included 64 patients with a total of 90 lesions treated with SBRT. LC at 1 and 2 years was 94.9 %, 91 % at 3 years. Median local control was not reached. Median OS was 16.5 months, OS at 1, 2 and 3 years was 87.5 %, 60.9 % and 51.9 %, respectively. Median DMFS was 8.3 months, DMFS at 1, 2 and 3 years was 38.1 %, 20.6 % and 16 % respectively. At univariate analysis, local response to SBRT was found to be statistically linked with better OS, DMFS and STFS.

CONCLUSION

SBRT is a safe and valid option in oligometastatic breast cancer patients, with very high rates of local control. An optimal selection of patients is likely needed to improve survival outcomes and reduce the rate of distant progression.

Machine-learning prediction of treatment response to stereotactic body radiation therapy in oligometastatic gynecological cancer: A multi-institutional study

BACKGROUND AND PURPOSE

We aimed to develop and validate different machine-learning (ML) prediction models for the complete response of oligometastatic gynecological cancer after SBRT.

MATERIAL AND METHODS

One hundred fifty-seven patients with 272 lesions from 14 different institutions and treated with SBRT with radical intent were included. Thirteen datasets including 222 lesions were combined for model training and internal validation purposes, with an 80:20 ratio. The external testing dataset was selected as the fourteenth Institution with 50 lesions. Lesions that achieved complete response (CR) were defined as responders. Prognostic clinical and dosimetric variables were selected using the LASSO algorithm. Six supervised ML models, including logistic regression (LR), classification and regression tree analysis (CART) and support vector machine (SVM) using four different kernels, were trained and tested to predict the complete response of uterine lesions after SBRT. The performance of models was assessed by receiver operating characteristic curves (ROC), area under the curve (AUC) and calibration curves. An explainable approach based on SHapley Additive exPlanations (SHAP) method was deployed to generate individual explanations of the model's decisions.

RESULTS

63.6% of lesions had a complete response and were used as ground truth for the supervised models. LASSO strongly associated complete response with three variables, namely the lesion volume (PTV), the type of lesions (lymph-nodal versus parenchymal), and the biological effective dose (BED10), that were used as input for ML modeling. In the training set, the AUCs for complete response were 0.751 (95% CI: 0.716-0.786), 0.766 (95% CI: 0.729-0.802) and 0.800 (95% CI: 0.742-0.857) for the LR, CART and SVM with a radial basis function kernel, respectively. These models achieve AUC values of 0.727 (95% CI: 0.669-0.795), 0.734 (95% CI: 0.649-0.815) and 0.771 (95% CI: 0.717-0.824) in the external testing set, demonstrating excellent generalizability.

CONCLUSION

ML models enable a reliable prediction of the treatment response of oligometastatic lesions receiving SBRT. This approach may assist radiation oncologists to tailor more individualized treatment plans for oligometastatic patients.

Oligometastasis: Expansion of Curative Treatments in the Field of Oncology

Oligometastasis is defined as the presence of several limited metastatic lesions and is generally limited to three or fewer than five metastatic lesions. Previously, the treatment of metastatic cancer aimed to alleviate symptoms rather than cure them; however, the use of immunotherapy or targeted therapy has greatly improved patient life expectancy. Additionally, the effectiveness and safety of local treatment have recently been proven for oligometastatic cancers and have significantly improved patient survival and decreased recurrence rates. A few metastatic studies on lung cancer have demonstrated the usefulness of combining radiation therapy and immunotherapy. Recently, local and targeted therapy combinations have shown promising results in treating non-small cell lung cancer, predominantly caused by the epidermal growth factor receptor and anaplastic lymphoma kinase gene mutations, suggesting the potential of these new treatment strategies. It is well known that oligometastasis has better clinical results than polymetastasis; however, research on the biological profile of oligometastasis is still lacking. Studies using circulating tumor DNA and circulating tumor cells are at the initial stages of providing a better understanding of oligometastatic cancers, and the biological characteristics of these cancers may be revealed based on more diverse studies. With the development of these treatments, the prognosis for patients with oligometastatic cancers is steadily improving, and if the biological profile is revealed, customized treatment may be provided.

The pattern of failure after Stereotactic Radiation Therapy (SRT) for oligo-metastases: predictive factors for poly-progression

PURPOSE

Patients with oligo-metastatic disease (OMD) can be safely treated with Stereotactic Radiation Therapy (SRT). Further disease progression is common in these patients. In most cases, patients relapse again with oligo-metastases, however some can experience a poly-progression after a local ablative treatment (LAT). The purpose of this study was to retrospectively identify factors associated with poly-progression in patients receiving SRT for OMD.

METHODS

Data from a monocentric database were retrospectively analyzed. Patients treated with SRT for OMD and who developed progression after LAT were selected. Patients were categorized as oligo- or poly-progressive according to the number of new/progressing metastases (≤ or > 5). Herein, we analyzed data about patients' characteristics, oligo-metastatic presentation and radiation treatment characteristics to evaluate their relationship with progression type.

RESULTS

From 2013 to 2021, data on 700 patients progressing after LAT were analyzed. Among them, 227 patients (32.4%) experienced a poly-progression; the median time to poly-progression was 7.72 months (range 1-79.6). Five variables associated with poly-progression were found to be statistically significant in the univariate analysis: performance status (p < 0.001), site of the primary tumor (p = 0.016), ablative dose (p = 0.002), treated site (p = 0.002), single or double organ (p = 0.03). Of those, all but the number of involved organs retained their significant predictive value on the multivariate analysis.

CONCLUSION

Our study identified four independent factors associated with poly-progression in patients with OMD receiving SRT. Our data may support comprehensive characterization of OMD, better understanding of factors associated with progression.

Partial tumor irradiation plus pembrolizumab in treating large advanced solid tumor metastases

BACKGROUNDWe previously demonstrated the safety of stereotactic body radiotherapy followed by pembrolizumab (SBRT+P) in patients with advanced solid tumors. This phase I clinical trial was expanded to study the safety of partial tumor irradiation (partial-Rx). We assessed irradiated local failure (LF) and clinical outcomes with correlations to biomarkers including CD8+ T cell radiomics score (RS) and circulating cytokines.METHODSPatients received SBRT to 2-4 metastases and pembrolizumab for up to 7 days after SBRT. Tumors measuring up to 65 cc received the full radiation dose (complete-Rx), whereas tumors measuring more than 65 cc received partial-Rx. Landmark analysis was used to assess the relationship between tumor response and overall survival (OS). Multivariable analysis was performed for RS and circulating cytokines.RESULTSIn the combined (expansion plus original) cohort, 97 patients (219 metastases) were analyzed and received SBRT+P. Forty-six (47%) patients received at least 1 partial-Rx treatment. There were 7 (7.2%)dose-limiting toxicities (DLTs). 1-year LF was 7.6% overall, and 13.3% and 5.4% for partial-Rx and complete-Rx tumors, respectively (HR 2.32, 95% CI 0.90-5.97, P = 0.08). The overall, unirradiated, and irradiated objective response rates were 22%, 12%, and 34%, respectively. Irradiated tumor response to SBRT+P was associated with prolonged OS; 1-year OS was 71% (responders), 42% (mixed-responders), and 0% (nonresponders) (P < 0.01). High-RS was significantly associated with improved LF, progression-free survival (PFS), and OS. Elevated circulating IL-8 was independently associated with inferior PFS and OS.CONCLUSIONSBRT+P is safe in patients with large, advanced solid tumors. Additional studies are warranted to assess noninferiority of complete versus partial irradiation of tumors in the setting of immunotherapy.TRIAL REGISTRATIONClinicaltrials.gov NCT02608385FUNDINGMerck Investigator Studies Program; Hillman Fellows for Innovative Cancer Research Program; NIH grants UM1CA186690-06, P50CA254865-01A1, P30CA047904-32, and R01DE031729-01A1.

Effectiveness of lenvatinib plus immune checkpoint inhibitors in primary advanced hepatocellular carcinoma beyond oligometastasis

BACKGROUND

Targeted therapy combined with immune checkpoint inhibitors is considered a promising treatment for primary advanced hepatocellular carcinoma (HCC). Nevertheless, the difference between synchronous and asynchronous treatment of lenvatinib with programmed death receptor-1 (PD-1) inhibitor in advanced HCC is still unclear. The aim of this investigation is to evaluate the effectiveness of synchronous and asynchronous of lenvatinib and PD-1 inhibitor on the advanced HCC beyond oligometastasis.

METHODS

In this study, 213 patients from four institutions in China were involved. Patients were split into two collections: (1) lenvatinib plus PD-1 inhibitor were used synchronously (synchronous treatment group); (2) patients in asynchronous treatment group received PD-1 inhibitor after 3 months of lenvatinib treatment prior to tumour progression. To analyse progression-free survival (PFS), overall survival (OS), efficacy and safety of patients in both groups, we employed propensity score matching (PSM).

RESULTS

The 6-, 12- and 24-month OS rates were 100%, 93.4% and 58.1% in the synchronous treatment group and 100%, 71.5% and 25.3% in the asynchronous treatment group, respectively. In contrast to the asynchronous treatment group, the group treated synchronously exhibited a substantially enhanced OS (hazard ratio [HR], 0.45; 95% confidence interval [CI], 0.30-0.66; p < .001). The 6-, 12- and 18-month PFS rates were 82.6%, 42.6% and 10.8% in the synchronous treatment group and 63.3%, 14.2% and 0% in the asynchronous treatment group, respectively. A significant difference was observed in the PFS rate (HR, 0.46; 95% CI, 0.33-0.63; p < .001) between the two collections.

CONCLUSIONS

Patients with advanced HCC beyond oligometastasis, simultaneous administration of lenvatinib and PD-1 inhibitor led to significant improvements in survival.

Survival advantage of locoregional and systemic therapy in oligometastatic breast cancer: an international retrospective cohort study (OLIGO-BC1)

BACKGROUND

An international retrospective cohort study was conducted to clarify the survival advantage of combination therapy with locoregional and systemic therapy (ST) in oligometastatic breast cancer (BC).

METHODS

Patients with oligometastatic BC diagnosed from 2007 to 2012 were enrolled in center hospitals in China, Korea and Japan. It was defined as a low-volume metastatic disease at up to five sites and not necessarily in the same organ. Cases with brain, pleural, peritoneal and pericardial metastases were excluded. The primary endpoint was overall survival (OS) from the initial diagnosis of oligometastases. OS was summarized using the Kaplan-Meier method. A multivariable Cox regression model was used to estimate the hazard ratio (HR) for clinicopathological factors.

RESULTS

Among 1,295 cases registered from February 2018 to May 2019, 932 remained for analysis after the exclusion of unavailable cases and locoregional recurrence. One metastatic site was found in 400 cases, 2 in 243, 3 in 130, 4 in 86 and 5 in 73. At the median follow-up of 4.5 years, 5-year OS was 54.7% and 39.7% for 321 cases in the combination therapy group and 611 cases in the ST group, respectively. An adjusted HR was 0.66 (95% confidence interval: 0.55, 0.79). Some types of ST without chemotherapy alone, younger age, ECOG performance status 0, early-stage BC, non-triple negative subtype, fewer metastatic sites and longer duration of surgery to relapse were significantly favorable prognostic factors.

CONCLUSION

Combination therapy may be considered for longer survival under some conditions in oligometastatic BC.

Ten-year experience of bone SBRT in breast cancer: analysis of predictive factors of effectiveness

PURPOSE

Data on the benefit of stereotactic body radiation therapy (SBRT) in patients with breast cancer (BC) and bone metastases remain limited. The purpose of this study is to report our 10-year experience of bone SBRT, analyzing toxicity and prognostic factors for local control (LC); progression-free survival, and overall survival (OS).

METHODS/PATIENTS

We analyzed all spine and non-spine bone SBRT performed in patients with BC during the 2012-2022 period at our institution. Treatments carried out with ablative intent in stereotactic conditions with dose/fraction ≥ 5 Gy in 5 or fewer sessions were considered. Demographic, treatment, and toxicity data were recorded according to CTCAEv4. Risk factors were assessed through univariate and multivariate analysis by Cox regression.

RESULTS

60 bone SBRT treatments were performed during the study period. 75% were spine SBRT and 25% were non-spine SBRT (median BED₄Gy was 80 Gy₄). The median age was 52.5 years (34-79). The median tumor volume was 2.9 cm³ (0.5-39.4). The median follow-up was 32.4 months (1.2-101.7). 1 and 2 years LC were 92.9 and 86.6%, respectively. 1 and 2 years OS were 100 and 90.6%, respectively. Multivariate analysis (MVA) associated volume of the treated lesion ≥ 13 cm³ with worse LC (p = 0.046; HR 12.1, 95%CI = 1.1-140.3). In addition, deferring SBRT > 3 months after lesion diagnosis to prioritize systemic treatment showed a significant benefit, improving the 2 years LC up to 96.8% vs. 67.5% for SBRT performed before this period (p = 0.031; HR 0.1, 95%CI = 0.01-0.8). Hormonal receptors, the total number of metastases, and CA15-3 value were significantly associated with OS in MVA. During follow-up, three non-spine fractures (5%) were observed.

CONCLUSIONS

According to our data, bone SBRT is a safe and effective technique for BC. Upfront systemic treatment before SBRT offers a benefit in LC. Therefore, SBRT should be considered after prior systemic treatment in this population.

A Precise Approach for Radiotherapy of Breast Cancer

Radiotherapy is an integral part of the multidisciplinary management of breast cancer (BC). There have been multiple recent advances in the delivery of radiotherapy, reviewed with a critical discussion of the evidence from trials investigating adjuvant ultra-hypofractionation and partial breast irradiation for early-stage BC, and the locoregional management of lymph nodes in locally advanced BC. Multiple precision medicine-based approaches have been developed as prognostic and/or predictive for BC patients and identifying biomarkers of radioresistance could help identify patients that may benefit from dose-escalated radiotherapy or radiosensitizers. Radiotherapy after breast reconstruction is an area of current controversy in the field, and we evaluated the decision-making considerations in this situation. The oligometastatic state is an emerging field for many cancer sites based on recent trials investigating ablative radiotherapy for oligometastatic BC. This chapter is an overview of radiotherapy for BC, with a focus on recent advances in early-stage, locally advanced, and oligometastatic disease.

Definitive Local Consolidative Therapy for Oligometastatic Solid Tumors: Results From the Lead-in Phase of the Randomized Basket Trial EXTEND

PURPOSE

The benefit of local consolidative therapy (LCT) for oligometastasis across histologies remains uncertain. EXTernal beam radiation to Eliminate Nominal metastatic Disease (EXTEND; NCT03599765) is a randomized phase 2 basket trial evaluating the effectiveness of LCT for oligometastatic solid tumors. We report here the prospective results of the single-arm "lead-in" phase intended to identify histologies most likely to accrue to histology-specific endpoints in the randomized phase.

METHODS AND MATERIALS

Eligible histologies included colorectal, sarcoma, lung, head and neck, ovarian, renal, melanoma, pancreatic, prostate, cervix/uterine, breast, and hepatobiliary. Patients received LCT to all sites of active metastatic disease and primary/regional disease (as applicable) plus standard-of-care systemic therapy or observation. The primary endpoint in EXTEND was progression-free survival (PFS), and the primary endpoint of the lead-phase was histology-specific accrual feasibility. Adverse events were graded by Common Terminology Criteria for Adverse Events version 4.0.

RESULTS

From August 2018 through January 2019, 50 patients were enrolled and 49 received definitive LCT. Prostate, breast, and kidney were the highest enrolling histologies and identified for independent accrual in the randomization phase. Most patients (73%) had 1 or 2 metastases, most often in lung or bone (79%), and received ablative radiation (62%). Median follow-up for censored patients was 38 months (range, 16-42 months). Median PFS was 13 months (95% confidence interval, 9-24), 3-year overall survival rate was 73% (95% confidence interval, 57%-83%), and local control rate was 98% (93 of 95 tumors). Two patients (4%) had Common Terminology Criteria for Adverse Events grade 3 toxic effects related to LCT; no patient had grade 4 or 5 toxic effects.

CONCLUSIONS

The prospective lead-in phase of the EXTEND basket trial demonstrated feasible accrual, encouraging PFS, and low rates of severe toxic effects at mature follow-up. The randomized phase is ongoing with histology-based baskets that will provide histology-specific evidence for LCT in oligometastatic disease.

Long-Term Outcomes and Genetic Predictors of Response to Metastasis-Directed Therapy Versus Observation in Oligometastatic Prostate Cancer: Analysis of STOMP and ORIOLE Trials

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The initial STOMP and ORIOLE trial reports suggested that metastasis-directed therapy (MDT) in oligometastatic castration-sensitive prostate cancer (omCSPC) was associated with improved treatment outcomes. Here, we present long-term outcomes of MDT in omCSPC by pooling STOMP and ORIOLE and assess the ability of a high-risk mutational signature to risk stratify outcomes after MDT. The primary end point was progression-free survival (PFS) calculated using the Kaplan-Meier method. High-risk mutations were defined as pathogenic somatic mutations within ATM, BRCA1/2, Rb1, or TP53. The median follow-up for the whole group was 52.5 months. Median PFS was prolonged with MDT compared with observation (pooled hazard ratio [HR], 0.44; 95% CI, 0.29 to 0.66; P value < .001), with the largest benefit of MDT in patients with a high-risk mutation (HR high-risk, 0.05; HR no high-risk, 0.42; P value for interaction: .12). Within the MDT cohort, the PFS was 13.4 months in those without a high-risk mutation, compared with 7.5 months in those with a high-risk mutation (HR, 0.53; 95% CI, 0.25 to 1.11; P = .09). Long-term outcomes from the only two randomized trials in omCSPC suggest a sustained clinical benefit to MDT over observation. A high-risk mutational signature may help risk stratify treatment outcomes after MDT.

Systemic Therapy Combined with Locoregional Therapy Improved Survival in Oligometastatic Breast Cancer: A Single-Center Retrospective Cohort Study

The optimal therapeutic options, adding locoregional therapy (LRT) to systemic therapy (ST) or not, for patients with oligometastatic breast cancer (OMBC) have not been fully elucidated. Hence, we designed a retrospective observational study which enrolled patients with measurable extracranial OMBC having less than 5 metastatic lesions not necessarily in the same organ. We retrospectively reviewed a total of 199 patients diagnosed with extracranial OMBC, including 28 receiving ST followed by LRT (ST to LRT group), 44 receiving LRT followed by ST (LRT to ST group), and 127 receiving ST alone (ST alone group). After a median follow-up of 28.7 months, patients receiving both ST and LRT had a significantly better prognosis than those receiving ST alone: the median progression-free survival (PFS) was 16.3, 14.0, and 9.3 months (P < 0.001) and the median overall survival (OS) was 39.8, 70.5, and 26.7 months (P < 0.001) in the ST to LRT, LRT to ST, and ST alone groups, respectively. Sequence of ST and LRT had no significant impact on survival among patients receiving both. Further exploratory analysis identified ST plus LRT as an independent predictor for longer PFS. In conclusion, we demonstrated that adding LRT to ST was associated with survival benefits for patients with OMBC, and further prospective studies were warranted.

Ways to improve breast cancer patients' management and clinical outcome: The 2020 Assisi Think Tank Meeting

We report on the third Assisi Think Tank Meeting (ATTM) on breast cancer, a brainstorming project which involved European radiation and clinical oncologists who were dedicated to breast cancer research and treatment. Held on February 2020, the ATTM aimed at identifying key clinical questions in current clinical practice and "grey" areas requiring research to improve management and outcomes. Before the meeting, three key topics were selected: 1) managing patients with frailty due to either age and/or multi-morbidity; 2) stereotactic radiation therapy and systemic therapy in the management of oligometastatic disease; 3) contralateral breast tumour prevention in BCRA-mutated patients. Clinical practice in these areas was investigated by means of an online questionnaire. In the lapse period between the survey and the meeting, the working groups reviewed data, on-going studies and the clinical challenges which were then discussed in-depth and subjected to intense brainstorming during the meeting; research protocols were also proposed. Methodology, outcome of discussions, conclusions and study proposals are summarized in the present paper. In conclusion, this report presents an in-depth analysis of the state of the art, grey areas and controversies in breast cancer radiation therapy and discusses how to confront them in the absence of evidence-based data to guide clinical decision-making.

Predictors of Pneumonitis in Combined Thoracic Stereotactic Body Radiotherapy and Immunotherapy

PURPOSE

Thoracic stereotactic body radiotherapy (SBRT) is associated with high rates of local control but carries a risk of pneumonitis. Immunotherapy is a standard treatment for patients with metastatic disease but can also cause pneumonitis. To evaluate the feasibility and safety of thoracic SBRT with systemic immunotherapy, clinical outcomes of patients treated with immune checkpoint blockade (ICB) and SBRT on prospective trials were reviewed.

METHODS AND MATERIALS

Three consecutive phase 1 trials of combination SBRT and ICB conducted between 2016-2020 for widely metastatic solid tumors were reviewed. The protocols mandated adherence to NRG BR001/BR002 OAR constraints, resulting in <100% coverage of some target volumes. ICB was administered either sequentially (within 7 days after completion of SBRT) or concurrently (before or at the start of SBRT), depending on protocol. Endpoints included pneumonitis, dose-volume constraints, local failure, and overall survival (OS). The cumulative incidence estimator and Kaplan-Meier method were used.

RESULTS

123 patients met eligibility with 311 metastases irradiated. The most common histologies included non-small cell lung cancer (33%) and colorectal cancer (12%). Median follow up was 12 months. The overall rate of grade 3+ pneumonitis was 8.1%. 1-year local failure was 3.6%. Established dosimetric parameters were significantly associated with the development of pneumonitis (p<0.05). In most patients, the lungs were not challenged with high doses of radiation, defined as receiving ≥75% of the maximum for a given lung dose-volume constraint. Patients who were challenged were not found to have a significantly higher risk of pneumonitis.

CONCLUSIONS

In the largest series of thoracic SBRT and immunotherapy, local control was excellent with acceptable toxicity and support the conclusion that established dose-volume constraints for the lung are safe. However, these results highlight the potential value in reporting of OARs being challenged with doses approaching protocol specified limits.

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

BACKGROUND

There is increasing evidence for the integration of locally ablative therapy into multimodality treatment of oligometastatic disease (OMD). To support standardised data collection, analysis, and comparison, a consensus OMD classification based on fundamental disease and treatment characteristics has previously been established. This study investigated the completeness of reporting the proposed OMD characteristics in literature and evaluated whether the proposed OMD classification system can be applied to the historical data.

METHODS

A systematic literature review was performed in Medline, Embase, and Cochrane, searching for prospective and retrospective studies, where SBRT was a treatment component of OMD. Reporting of the OMD characteristics as described in the EORTC/ESTRO classification was analyzed, feasibility to retrospectively classify the proposed OMD states was investigated and the impact of the categorisation on overall survival (OS) was evaluated.

RESULTS

Our study shows incomplete reporting of the proposed OMD characteristics. The most fully reported characteristic was 'type of involved organs' (88/95 studies); 'history of cancer progression' was the least reported (not mentioned in 50/95 studies). Retrospective OMD classification of existing literature was only possible for 7/95 studies. With respect to categorization as de novo, repeat or induced OMD, homogeneous patient cohorts were observed in 21/95 studies, most frequently de novo OMD, in 20 studies. Differences in OS at 2, 3, or 5 years were not statistically significant between the different states. OS was significantly influenced by primary tumor histology, with superior OS observed for prostate cancer and worst OS observed for non-small cell lung cancer.

CONCLUSION

The largely incomplete reporting of the proposed OMD characteristics hampers a retrospective classification of existing literature. To facilitate future comparison of individual studies, as well as validation of the OMD classification, comprehensive reporting of OMD characteristics using standardised terminology is recommended, as proposed by the EORTC/ESTRO classification system and following ESTRO-ASTRO consensus.

Curative intent Stereotactic Ablative Radiation Therapy (SABR) for treatment of lung oligometastases from head and neck squamous cell carcinoma (HNSCC): a multi-institutional retrospective study

OBJECTIVES

The aim of this retrospective study was to assess outcomes of SABR for metachronous isolated lung oligometastases from HNSCC.

METHODS

For patients who developed isolated, 1 or 2 lungs lesions (<5cm) consistent with metastases from HNSCC, the indication of SABR was validated in a multidisciplinary tumor board. All patients were monitored by CT or PET CT after SABR (Stereotactic Ablative Body Radiation) for HNSCC.

RESULTS

Between November 2007 and February 2018, 52 patients were treated with SABR for metachronous lung metastases. The median time from the treatment of the primary HNSCC to the development of lung metastases was 18 months (3-93). The cohort's median age was 65.5 years old (50-83). The vast majority (94.2%) received 60 Gy in three fractions. Forty-one patients (78.5%) presented a solitary lung metastasis, while 11 patients (21.5%) had two lung metastases. With a median follow-up of 45.3 months, crude local and metastatic control rates were 74 and 38%, respectively. 1 year and 2 year Overall Survival (OS) were 85.8 and 65.9%, respectively. The median OS was 46.8 months. About one-fourth of patients were retreated by SABR for distant pulmonary recurrence. The treatment was well tolerated with only one patient who reported ≥ grade 3 toxicity (1.9%).

CONCLUSION

In selected metastatic HNSCC patients, early detection and treatment of lung metastases with SABR is effective and safe. Prospective studies are required to validate this potential shift.

ADVANCES IN KNOWLEDGE

Patients with oligometastases and controlled primary HNSCC seem to benefit from metastasis directed therapies.

Oligoscore: a clinical score to predict overall survival in patients with oligometastatic disease treated with stereotactic body radiotherapy

BACKGROUND

to find clinical features that can predict prognosis in patients with oligometastatic disease treated with stereotactic body radiotherapy (SBRT).

MATERIAL AND METHODS

Patients with less than 5 metastases in less than 3 different body sites were included in the analysis. Various clinical and treatment parameters were analyzed to create a Cox proportional hazard model for Overall Survival (OS). Subsequently, significant variables were used to create a score.

RESULTS

997 patients were analyzed. Median OS was 2.61 years, 1 and 3 years OS was respectively 85% and 43%. Location of the primary tumor, performance status, site of irradiated metastases, presence of extratarget non irradiated lesions and RT dose were significant prognostic factors for OS. These parameters were used to create a score and to distinguish three different classes, with median OS of 5.67 years in low risk, 2.47 years in intermediate risk and 1.82 years in high risk group.

CONCLUSION

moving from easily accessible clinical parameters, a score was created to help the physician's decision about the better treatment or combination of treatments for the individual patient.

GOECP/SEOR radiotheraphy guidelines for non-small-cell lung cancer

Non-small cell lung cancer (NSCLC) is a heterogeneous disease accounting for approximately 85% of all lung cancers. Only 17% of patients are diagnosed at an early stage. Treatment is multidisciplinary and radiotherapy plays a key role in all stages of the disease. More than 50% of patients with NSCLC are treated with radiotherapy (curative-intent or palliative). Technological advances-including highly conformal radiotherapy techniques, new immobilization and respiratory control systems, and precision image verification systems-allow clinicians to individualize treatment to maximize tumor control while minimizing treatment-related toxicity. Novel therapeutic regimens such as moderate hypofractionation and advanced techniques such as stereotactic body radiotherapy (SBRT) have reduced the number of radiotherapy sessions. The integration of SBRT into routine clinical practice has radically altered treatment of early-stage disease. SBRT also plays an increasingly important role in oligometastatic disease. The aim of the present guidelines is to review the role of radiotherapy in the treatment of localized, locally-advanced, and metastatic NSCLC. We review the main radiotherapy techniques and clarify the role of radiotherapy in routine clinical practice. These guidelines are based on the best available evidence. The level and grade of evidence supporting each recommendation is provided.

Radiotherapy at oligoprogression for metastatic castration-resistant prostate cancer patients: a multi-institutional analysis

PURPOSE

To retrospectively estimate the impact of radiotherapy as a progression-directed therapy (PDT) in oligoprogressive metastatic castration-resistant prostate cancer (mCRPC) patients under androgen receptor-target therapy (ARTT).

MATERIALS AND METHODS

mCRPC patients are treated with PDT. End-points were time to next-line systemic treatment (NEST), radiological progression-free survival (r-PFS) and overall survival (OS). Toxicity was registered according to Common Terminology Criteria for Adverse Events v4.0. Survival analysis was performed using the Kaplan-Meier method; univariate and multivariate analyses were performed.

RESULTS

Fifty-seven patients were analyzed. The median follow-up after PDT was 25.2 months (interquartile, 17.1-44.5). One-year NEST-free survival, r-PFS and OS were 49.8%, 50.4% and 82.1%, respectively. At multivariate analysis, polymetastatic condition at diagnosis of metastatic hormone-sensitive prostate cancer (mHSPC) (HR 2.82, p = 0.004) and PSA doubling time at diagnosis of mCRPC (HR 2.76, p = 0.006) were associated with NEST-free survival. The same variables were associated with r-PFS (HR 2.32, p = 0.021; HR 2.24, p = 0.021). One patient developed late grade ≥ 2 toxicity.

CONCLUSION

Our study shows that radiotherapy in oligoprogressive mCRPC is safe, is effective and seems to prolong the efficacy of ARTT in patients who otherwise would have gone systemic treatment switch, positively affecting disease progression. Prospective trials are needed.

Stereotactic body radiotherapy to treat breast cancer oligometastases: A systematic review with meta-analysis

OBJECTIVES

Stereotactic ablative radiotherapy (SABR) has been reported to be an effective treatment for oligometastatic disease from different primary cancer sites. Here we assess the effectiveness and safety of SABR for oligometastatic breast cancer patients by performing a meta-analysis.

METHODS

Following PRISMA and MOOSE guidelines, a systematic review and meta-analysis was performed. Eligible studies were identified on Medline, Embase, Cochrane Library, and annual meetings proceedings from 1990 to June 2021. A meta-regression analysis was performed to assess if there was a correlation between moderator variables and outcomes, and a p-value <0.05 was considered significant.

RESULTS

Ten studies met criteria for inclusion, comprising 467 patients and 653 treated metastases. The 1- and 2-year local control rates were 97% (95% CI 95-99%), and 90% (95% CI 84-94%), respectively. Overall survival (OS) was 93% (95% CI 89-96%) at 1 year, 81% (95% CI 72-88%) at 2 years. The rate of any grade 2 or 3 toxicity was 4.1 % (95% CI 0.1-5%), and 0.7% (0-1%), respectively. In the meta-regression analysis, only prospective design (p = 0.001) and bone-only metastases (p = 0.01) were significantly associated with better OS. In the subgroup analysis, the OS at 2y were significantly different comparing HER2+, HR+/HER2(-) and triple negative breast cancer 100%, 86% and 32%, p = 0.001. For local control outcomes, hormone receptor status (p = 0.01) was significantly associated on meta-regression analysis.

CONCLUSION

SABR for oligometastatic breast cancer is safe and associated with high rates of local control. Longer follow-up of existing data and ongoing prospective trials will help further define the role of this management strategy.

Diagnosis, biology and epidemiology of oligometastatic breast cancer

Does oligometastatic breast cancer (OMBC) deserve a dedicated treatment? Although some authors recommend multidisciplinary management of OMBC with a curative intent, there is no evidence proving this strategy beneficial in the absence of a randomized trial. The existing literature sheds little light on OMBC. Incidence is unknown; data available are either obsolete or biased; there is no consensus on the definition of OMBC and metastatic sites, nor on necessary imaging techniques. However, certain proposals merit consideration. Knowledge of eventual specific OMBC biological characteristics is limited to circulating tumor cell (CTC) counts. Given the data available for other cancers, studies on microRNAs (miRNAs), circulating tumor DNA (ctDNA) and genomic alterations should be developed Finally, safe and effective therapies do exist, but results of randomized trials will not be available for many years. Prospective observational cohort studies need to be implemented.

Late metastatic presentation is associated with improved survival and delayed wide-spread progression after ablative stereotactic body radiotherapy for oligometastasis

Background

Stereotactic body radiotherapy (SBRT) is increasingly used to treat oligometastatic disease (OMD), but the effect of metastasis timing on patient outcomes remains uncertain.

Methods

An international database of patients with OMD treated with SBRT was assembled with rigorous quality assurance. Early versus late metastases were defined as those diagnosed ≤24 versus >24 months from the primary tumor. Overall survival (OS), progression‐free survival (PFS), and incidences of wide‐spread progression (WSP) were estimated using multivariable Cox proportional hazard models stratified by primary tumor types.

Results

The database consists of 1033 patients with median follow‐up of 24.1 months (0.3–104.7). Late metastatic presentation (N = 427) was associated with improved OS compared to early metastasis (median survival 53.6 vs. 33.0 months, hazard ratio [HR] 0.59, 95% confidence interval [CI]: 0.47–0.72, p < 0.0001). Patients with non‐small cell lung cancer (NSCLC, N = 255, HR 0.49, 95% CI: 0.33–0.74, p = 0.0005) and colorectal cancer (N = 235, HR 0.50, 95% CI: 0.30–0.84, p = 0.008) had better OS if presenting with late metastasis. Late metastasis correlated with longer PFS (median 17.1 vs. 9.0 months, HR 0.71, 95% CI: 0.61–0.83, p < 0.0001) and lower 2‐year incidence of WSP (26.1% vs. 43.6%, HR 0.60, 95% CI: 0.49–0.74, p < 0.0001). Fewer WSP were observed in patients with NSCLC (HR 0.52, 95% CI: 0.33–0.83, p = 0.006) and kidney cancer (N = 63, HR 0.37, 95% CI: 0.14–0.97, p = 0.044) with late metastases. Across cancer types, greater SBRT target size was a significant predictor for worse OS.

Conclusion

Late metastatic presentation is associated with improved survival and delayed progression in patients with OMD treated with SBRT.

Treatment Strategies for Oligometastatic Breast Cancer

OPINION STATEMENT

Oligometastatic breast cancer, typically defined as the presence of 1-5 metastases, represents an intermediate state between locally advanced and widely metastatic disease. Emerging research suggests that oligometastatic cancer has a unique molecular signature distinct from widely metastatic disease, and that it carries a superior prognosis. Owing to its more limited capacity for widespread progression, oligometastatic disease may benefit from aggressive ablative therapy to known metastases. Options for ablation include surgical excision, radiofrequency ablation, and hypofractionated image-guided radiotherapy (HIGRT). The phase II SABR-COMET trial, which enrolled patients with oligometastatic disease of multiple histologies and randomized them to HIGRT vs. standard of care, found a notable survival advantage in favor of HIGRT. Other data suggest that HIGRT may synergize with immunotherapy by releasing powerful cytokines that increase anti-tumor immune surveillance and by recruiting tumor infiltrating lymphocytes, helping to overcome resistance to therapy. There are many ongoing trials exploring the role of ablative therapy, most notably HIGRT, with or without immunotherapy, for the treatment of oligometastatic breast cancer.We believe that patients with oligometastatic breast cancer should be offered enrollment on prospective clinical trials when possible. Outside the context of a clinical trial, we recommend that select patients with oligometastatic breast cancer be offered treatment with a curative approach, including ablative therapy to all sites of disease if it can be safely accomplished. Currently, selection criteria to consider for ablative therapy include longer disease-free interval from diagnosis to metastasis (>2 years), fewer metastases, and fewer involved organs. Undoubtedly, new data will refine or even upend our understanding of the definition and optimal management of oligometastatic disease.

Evaluation of Safety of Stereotactic Body Radiotherapy for the Treatment of Patients With Multiple Metastases: Findings From the NRG-BR001 Phase 1 Trial

IMPORTANCE

Stereotactic body radiotherapy (SBRT) for oligometastases is hypothesized to improve survival and is increasingly used. Little evidence supports its safe use to treat patients with multiple metastases.

OBJECTIVE

To establish safety of SBRT dose schedules in patients with 3 to 4 metastases or 2 metastases in close proximity to each other.

DESIGN, SETTING, AND PARTICIPANTS

This phase 1 trial opened on August 4, 2014, and closed to accrual on March 20, 2018. Metastases to 7 anatomic locations were included: bone/osseous (BO), spinal/paraspinal (SP), peripheral lung (PL), central lung (CL), abdominal-pelvic (AP), mediastinal/cervical lymph node (MC), and liver (L). Six patients could be enrolled per anatomic site. The setting was a consortium of North American academic and community practice cancer centers participating in NRG Oncology trials. Patients with breast, prostate, or non-small cell lung cancer with 3 to 4 metastases or 2 metastases in close proximity (≤5 cm) amenable to SBRT were eligible for this phase 1 study. Statistical analyses were performed from December 31, 2017, to September 19, 2019.

INTERVENTIONS

The starting dose was 50 Gy in 5 fractions (CL, MC), 45 Gy in 3 fractions (PL, AP, L), and 30 Gy in 3 fractions (BO, SP).

MAIN OUTCOMES AND MEASURES

The primary end point was dose-limiting toxicity (DLT) defined by the Common Terminology Criteria for Adverse Events, version 4.0, as specific adverse events (AEs) of grades 3 to 5 (definite or probable per the protocol DLT definition) related to SBRT within 180 days of treatment. Dose levels were considered safe if DLTs were observed in no more than 1 of 6 patients per location; otherwise, the dose at that location would be de-escalated.

RESULTS

A total of 42 patients enrolled, 39 were eligible, and 35 (mean [SD] age, 63.1 [14.2] years; 20 men [57.1%]; 30 White patients [85.7%]) were evaluable for DLT. Twelve patients (34.3%) had breast cancer, 10 (28.6%) had non-small cell lung cancer, and 13 (37.1%) had prostate cancer; there was a median of 3 metastases treated per patient. Median survival was not reached. No protocol-defined DLTs were observed. When examining all AEs, 8 instances of grade 3 AEs, most likely related to protocol therapy, occurred approximately 125 to 556 days from SBRT initiation in 7 patients.

CONCLUSIONS AND RELEVANCE

This phase 1 trial demonstrated the safety of SBRT for patients with 3 to 4 metastases or 2 metastases in close proximity. There were no treatment-related deaths. Late grade 3 AEs demonstrate the need for extended follow-up in long-surviving patients with oligometastatic disease. Treatment with SBRT for multiple metastases has been expanded into multiple ongoing randomized phase 2/3 National Cancer Institute-sponsored trials (NRG-BR002, NRG-LU002).

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02206334.

Prognostic and Predictive Biomarkers in Oligometastatic Disease

Metastatic lesions are largely responsible for cancer-related deaths and are synonymous with a poor prognosis. However, this is not always true for patients with oligometastases whose disease may be amenable to curative-intent local therapies. It has been proposed that an "intermediate state" (oligometastasis) exists in between locoregional and advanced disease states; however, the clinical definition of oligometastasis varies, and there is limited understanding of how tumor biology differs between oligometastases and polymetastases. There is evidence that local therapies can extend survival in patients with oligometastases, yet patient selection for local intervention and/or systemic therapy remains a challenge. Prognostic and predictive biomarkers of oligometastatic disease are strongly needed to identify patient candidates most likely to gain survival benefit from local therapies and to aid in the incorporation of ablative treatments in the context of existing systemic therapies.

Characterization of Oligometastatic Disease in a Real-World Nationwide Cohort of 3447 Patients With de Novo Metastatic Breast Cancer

Background

Observational studies in metastatic breast cancer (MBC) show that long-term overall survival (OS) is associated with limited tumor burden, or oligo-MBC (OMBC). However, a uniform definition of OMBC is lacking. In this real-world nationwide cohort, we aimed to define the optimal OMBC threshold and factors associated with survival in patients with OMBC.

Methods

3535 patients aged younger than 80 years at diagnosis of de novo MBC in the Netherlands between January 2000 and December 2007 were included. Detailed clinical, therapy, and outcome data were collected from medical records of a sample of the patients. Using inverse-sampling-probability weighting, the analysis cohort (n = 3447) was constructed. We assessed OS according to number of metastases at diagnosis to determine the optimal OMBC threshold. Next, we applied Cox regression models with inverse-sampling-probability weighting to study associations with OS and progression-free survival in OMBC. All statistical tests were 2-sided.

Results

Compared with more than 5 distant metastases, adjusted hazard ratios for OS (with 95% confidence interval [CI] based on robust standard errors) for 1, 2-3, and 4-5 metastases were 0.70 (95% CI = 0.52 to 0.96), 0.63 (95% CI = 0.45 to 0.89), and 0.91 (95% CI = 0.61 to 1.37), respectively. Ten-year OS estimates for patients with no more than 3 vs more than 3 metastases were 14.9% and 3.4% (P < .001). In multivariable analyses, premenopausal andperimenopausal status, absence of lung metastases, and local therapy of metastases (surgery and/or radiotherapy) added to systemic therapy were statistically significantly associated with better OS and progression-free survival in OMBC, independent of local therapy of the primary tumor.

Conclusion

OMBC defined as MBC limited to 1-3 metastases was associated with favorable OS. In OMBC, local therapy of metastases was associated with better OS, particularly if patients were premenopausal or perimenopausal without lung metastases.

Stereotactic ablative radiotherapy in castration-resistant prostate cancer patients with oligoprogression during androgen receptor-targeted therapy

OBJECTIVES

To report outcomes of stereotactic body radiotherapy (SBRT) in metastatic castration-resistant prostate cancer (mCRPC) patients with oligoprogression (≤ 5 metastases) during first-line treatment with androgen receptor-targeted therapy (ARTT).

PATIENTS AND METHODS

Retrospective multi-institutional analysis of mCRPC patients treated with SBRT to oligoprogressive lesions during ARTT. End-points were time to next-line systemic treatment (NEST), radiological progression-free survival (r-PFS) and overall survival (OS). Toxicity was registered according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Survival analysis was performed using the Kaplan-Meier method, univariate and multivariate analysis (MVA) were performed.

RESULTS

Data from 34 patients were analyzed. Median NEST-free survival, r-PFS, and OS were 16.97, 13.47, and 38.3 months, respectively. At MVA, factors associated with worse NEST-free survival and r-PFS were polymetastatic burden at diagnosis of metastatic hormone-sensitive disease (hazard ratio [HR] 3.66, p = 0.009; HR 3.03, p = 0.034), PSA ≤ 7 ng/ml at mCRPC diagnosis (HR 0.23, p = 0.017; HR 0.19, p = 0.006) and PSADT ≤ 3 months at mCRPC diagnosis (HR 3.39, p = 0.026; HR 2.79, p = 0.037). Polymetastatic state at mHSPC diagnosis was associated with a decreased OS (HR 4.68, p = 0.029). No patient developed acute or late grade ≥ 2 toxicity.

CONCLUSION

Our results suggest that SBRT in oligoprogressive mCPRC is safe, effective and seems to prolong the efficacy of the ongoing systemic treatment positively affecting disease progression. Prospective trials are needed.

Oligometastatic Disease Management: Finding the Sweet Spot

Hematogenous dissemination represents a common manifestation of squamous cell carcinoma of the head and neck, and the recommended therapeutic options usually consist of systemically administered drugs with palliative intent. However, mounting evidence suggests that patients with few and slowly progressive distant lesions of small size may benefit from various local ablation techniques, which have already been established as standard-of-care modalities for example in colorectal and renal cell carcinomas and in sarcomas. In principle, serving as radical approaches to eradicate cancer, these interventions can be curative. Their impact on local control and overall survival has been shown in numerous retrospective and prospective studies. The term oligometastatic refers to the number of distant lesions which should generally not surpass five in total, ideally in one organ. Currently, surgical resection remains the method of choice supported by the majority of published data. More recently, stereotactic (ablative) body radiotherapy (SABR/SBRT) has emerged as a viable alternative. In cases technically amenable to such local interventions, several other clinical variables need to be taken into account also, including patient-related factors (general health status, patient preferences, socioeconomic background) and disease-related factors (primary tumor site, growth kinetics, synchronous or metachronous metastases). In head and neck cancer, patients presenting with late development of slowly progressive oligometastatic lesions in the lungs secondary to human papillomavirus (HPV)-positive oropharyngeal cancer are the ideal candidates for metastasectomy or other local therapies. However, literature data are still limited to say whether there are other subgroups benefiting from this approach. One of the plausible explanations is that radiological follow-up after primary curative therapy is usually not recommended because its impact on survival has not been unequivocal, which is also due to the rarity of oligometastatic manifestations in this disease. At the same time, aggressive treatment of synchronous metastases early in the disease course should be weighed against the risk of futile interventions in a disease with already multimetastatic microscopic dissemination. Therefore, attentive treatment sequencing, meticulous appraisal of cancer extension, refinement of post-treatment surveillance, and understanding of tumor biology and kinetics are crucial in the management of oligometastases.

Improved Survival Associated with Local Tumor Response Following Multisite Radiotherapy and Pembrolizumab: Secondary Analysis of a Phase I Trial

PURPOSE

Multisite stereotactic body radiotherapy followed by pembrolizumab (SBRT+P) has demonstrated safety in advanced solid tumors (ASTs). However, no studies have examined the relationships between irradiated tumor response, SBRT-induced tumor gene expression, and overall survival (OS).

PATIENTS AND METHODS

Patients with AST received SBRT (30-50 Gy in 3-5 fractions) to two to four metastases followed by pembrolizumab (200 mg i.v. every 3 weeks). SBRT was prescribed to a maximum tumor volume of 65 mL. Small metastases received the complete prescribed coverage (complete-Rx), while larger metastases received partial coverage (partial-Rx). Treated metastasis control (TMC) was defined as a lack of progression for an irradiated metastasis. Landmark analysis was used to assess the relationship between TMC and OS. Thirty-five biopsies were obtained from 24 patients: 19 pre-SBRT and 16 post-SBRT (11 matched) prior to pembrolizumab and were analyzed via RNA microarray.

RESULTS

Sixty-eight patients (139 metastases) were enrolled with a median follow-up of 10.4 months. One-year TMC was 89.5% with no difference between complete-Rx or partial-Rx. On multivariable analysis, TMC was independently associated with a reduced risk for death (HR, 0.36; 95% confidence interval, 0.17-0.75; P = 0.006). SBRT increased expression of innate and adaptive immune genes and concomitantly decreased expression of cell cycle and DNA repair genes in the irradiated tumors. Elevated post-SBRT expression of DNASE1 correlated with increased expression of cytolytic T-cell genes and irradiated tumor response.

CONCLUSIONS

In the context of SBRT+P, TMC independently correlates with OS. SBRT impacts intratumoral immune gene expression associated with TMC. Randomized trials are needed to validate these findings.

Management of oligo-metastatic and oligo-recurrent cervical cancer: A pattern of care survey within the EMBRACE research network

BACKGROUND

In the metastatic or recurrent cervical cancer, systemic chemotherapy constitutes the main treatment. Though there is an increasing use of high dose external radiation and brachytherapy in the metastatic setting, no consensus exists.

METHODS

A 17-item survey was designed with additional case-based questions to explore present management of oligo-metastatic and oligo-recurrent cervix cancer within EMBRACE research group participating sites. The questions were designed to elicit prevailing practices in the management of de-novo oligo-metastasis and oligo-recurrent setting after completing the primary treatment of cervix cancer. The survey was sent electronically with two rounds of email reminders to respond over a 2-week survey period. The online survey was designed such that it was mandatory to complete all questions. The responses were recorded and results were summarized as proportions and summary statistics were generated.

RESULTS

Twenty-two centers responded to this survey. A majority (90%) of respondents reported a low incidence of de-novo oligo-metastatic cervical cancer in their practice (<5%), with a higher proportion of patients with oligo-recurrence after completing primary treatment (5-10%). All responding sites preferred to treat pelvic disease in the de-novo oligo-metastatic setting albeit with different fractionation regimens. While 68.2% of respondents recommended chemo-radiation and brachytherapy, 31.8% considered additional systemic therapy. Overall 77.3% centers recommended the use of stereotactic ablative radiation therapy to oligo-metastasis. For out-of-field nodal recurrences, 63.7% of respondents considered treating with curative intent, while 59% preferred treating in-field recurrence with palliative intent. A vast majority of the participating centers (90%) have stereotactic radiation therapy capacity and would consider a clinical trial addressing oligo-metastatic and oligo-recurrent cervical cancer.

CONCLUSION

Although contemporary practice is variable, a substantial proportion of EMBRACE centers consider high dose radiation in de-novo metastatic and oligo-recurrence settings. However, there is clear need for a joint clinical protocol and prospective studies to address the role of high dose radiation within oligo-recurrent and oligo-metastatic scenarios.

Stereotactic body radiation therapy for oligometastatic gynecologic malignancies: A systematic review

OBJECTIVE

To assess the efficacy and safety of stereotactic body radiation therapy (SBRT) for oligometastatic gynecologic malignancies.

METHOD

A comprehensive search of the PubMed, Medline, and EMBASE databases was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. "Oligometastatic" was defined as a limited number of uncontrolled/untreated metastatic lesions (typically ≤ 5), including regional nodal metastases. Primary outcomes were response rate (complete response or partial response), local control of oligometastatic lesions, and toxicity.

RESULTS

Of 716 screened records, 17 studies (13 full length articles, 4 conference abstracts) were selected and analyzed as 16 unique studies. A total of 667 patients were treated with ~1071 metastatic lesions identified. Primary sites included ovarian (57.6%), cervical (27.1%), uterine (11.1%), vaginal (0.4%), vulvar (0.3%), and other/unspecified (3.4%). Most patients (65.4%) presented with a single metastatic lesion. Metastatic lesion sites included the abdomen (44.2%), pelvis (18.8%), thorax (15.5%), neck (4.6%), central nervous system (4.3%), bone (1.6%), and other/unspecified (11%). Of the lesions, 64% were nodal. Response rate (among 8 studies) ranged from 49% to 97%, with 7/8 studies reporting > 75% response rate. Local control ranged from 71% to 100%, with 14/16 studies reporting ≥ 80% local control. No grade ≥ 3 toxicities were observed in 9/16 (56%) studies. Median progression-free survival (PFS) (among 10 studies) ranged from 3.3 months to 21.7 months. Disease progression most commonly occurred outside of the SBRT radiation field (79% to 100% of failures).

CONCLUSIONS

SBRT for oligometastatic gynecologic malignancies is associated with favorable response and local control rates but a high rate of out-of-field progression and heterogeneous PFS. Additional study into rational combinations of SBRT and systemic therapy appears warranted to further improve patient outcomes.

Stereotactic body radiation therapy (SBRT) in recurrent, persistent or oligometastatic gynecological cancers

OBJECTIVE

SBRT is a well-tolerated technique and provides local-regional control in a variety of metastatic and recurrent tumor types. The role of SBRT in extracranial recurrent, persistent, or oligometastatic gynecological tumors is not well-studied. We therefore retrospectively analyzed a sizeable number of patients in this setting.

METHODS

We performed a retrospective review of 86 patients with 209 tumors treated at our institution with SBRT for recurrent, persistent, or oligometastatic extracranial gynecological tumors. The median follow-up was 20 months (range 1-91). The median SBRT dose was 24 Gy (range 10-50) delivered in a median of 4 fractions (range 1-6). The Kaplan-Meier curves and log rank tests were used to assess local control (LC) and overall survival (OS). Cox proportional hazards model was used to evaluate for covariates associated with LC and OS.

RESULTS

The 1- and 3-year LC were 80% and 68% respectively. The 1- and 3-year OS were 70% and 39%. 32% of the lesions demonstrated complete response, 23% partial response and 20% stable disease. SBRT achieved better local control in smaller tumors. Toxicity was typically mild with grade 1 gastrointestinal toxicity and fatigue being the most common. Only 4.3% of treatments resulted in grade 2 or greater toxicity. There was only one case of grade 3 and no grade 4 or 5 toxicities.

CONCLUSIONS

SBRT offers a high rate of local control with low incidence of toxicity, mainly grade 1 GI toxicity and fatigue, and provides effective salvage therapy for oligometastatic extracranial pelvic and extra-pelvic gynecological tumors.

Stereotactic Body Radiation Therapy (SBRT) in Pelvic Lymph Node Oligometastases

The role of stereotactic body radiation therapy (SBRT) in achieving durable local control and palliation of pain in pelvic lymph node oligometastatic disease is not well-studied. We performed a retrospective analysis of 30 patients with 43 pelvic lymph node oligometastases from various primary cancers all but one with non-prostate primaries treated at our institution with SBRT. The median follow-up time was 21 months. The median SBRT dose was 24 Gy in four fractions. The one-, two-, and five-year local control was 74%, 71%, and 70% and one-, two-, and five-year overall survival was 70%, 47%, and 31%. Toxicities were mild with no grade 3 or higher.

GOECP/SEOR clinical recommendations for lung cancer radiotherapy during the COVID-19 pandemic

The coronavirus disease 2019 crisis has had a major and highly complex impact on the clinical practice of radiation oncology worldwide. Spain is one of the countries hardest hit by the virus, with devastating consequences. There is an urgent need to share experiences and offer guidance on decision-making with regard to the indications and standards for radiation therapy in the treatment of lung cancer. In the present article, the Oncological Group for the Study of Lung Cancer of the Spanish Society of Radiation Oncology reviews the literature and establishes a series of consensus-based recommendations for the treatment of patients with lung cancer in different clinical scenarios during the present pandemic.

Diagnosis and Treatment of Bone Metastases in Breast Cancer: Radiotherapy, Local Approach and Systemic Therapy in a Guide for Clinicians

The standard care for metastatic breast cancer (MBC) is systemic therapies with imbrication of focal treatment for symptoms. Recently, thanks to implementation of radiological and metabolic exams and development of new target therapies, oligometastatic and oligoprogressive settings are even more common-paving the way to a paradigm change of focal treatments role. In fact, according to immunophenotype, radiotherapy can be considered with radical intent in these settings of patients. The aim of this literature review is to analyze available clinical data on prognosis of bone metastases from breast cancer and benefits of available treatments for developing a practical guide for clinicians.

The Role of Local Treatment in Oligometastatic and Oligoprogressive Cancer

BACKGROUND

Systemic treatment is standard for most types of cancer with disseminated metastases. The role of local treatment (LT) of individual tumor foci in patients with oligometastatic disease is unclear and the object of current scientific studies.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

Four randomized trials have shown that radical local treatment confers an advantage with respect to overall survival (OS), compared to systemic treatment alone, in patients with oligometastatic disease. In patients with synchronous metastases and a stable primary tumor, LT prolongs the median overall survival by approximately two years. A single randomized trial for oligometastatic small-cell lung cancer did not show any prolongation of overall survival. Local treatment increased the frequency of grade III side effects by approximately 10%.

CONCLUSION

Although local treatment already has a place in many guidelines on the basis of the findings of a small number of prospective and retrospective studies, a option of local treatment should be considered by an interdisciplinary tumor board individually for suitable patients.

Extracranial Stereotactic Body Radiotherapy in Oligometastatic or Oligoprogressive Breast Cancer

Purpose/Objective: Oligometastatic disease (OMD) and oligoprogressive disease (OPD) describe tumor states with a limited metastasization. In contrast to other disease states, treatment of OMD or OPD has not yet become common for breast cancer. We sought to understand the outcomes and toxicities of this treatment paradigm. Material/Methods: We retrospectively analyzed female breast cancer patients with OMD (≤3 metastases) or OPD (1 progressive lesion) who received stereotactic body radiotherapy (SBRT) for their respective extracranial metastatic lesions between 01/2002 and 07/2019. Survival analysis was performed using the Kaplan-Meier method with log-rank test being used for evaluation of significance. Cox regression was used to detect prognostic outcome factors. Toxicity was evaluated using the Common Terminology Criteria for Adverse Events (CTCAE v. 5.0). Results: Forty-six patients (70% OMD; 30% OPD) with 58 lesions met criteria for inclusion. The majority of treatments (34 out of 58; 58.6%) were delivered from 2017 to 2018. Treatment sites were bone, liver, lung [n = 19 (33%) for each site], and adrenal gland [n = 1 (1%)]. Median biologically effective dose (BED at α/β = 10) was 81.6 Gy (range: 45-112.5 Gy) and median planning target volume was 36.60 mL (range: 3.76-311.00 mL). At 2 years, local control (LC) was 89%, distant control (DC) was 44%, progression free survival (PFS) was 17% and overall survival (OS) was 62%. Multivariate analysis identified the diagnosis of a solitary metastasis as an independent prognostic factor for superior DC (HR = 0.186, CI [0.055; 0.626], p = 0.007) and PFS (HR = 0.363, CI [0.152; 0.863], p = 0.022). OS was independently inferior for patients treated at a higher age (HR = 5.788, CI [1.077; 31.119] p = 0.041). Nine (15.5%) grade I° and one (1.7%) grade II° toxicities were recorded, with no grade III° or higher toxicities. Conclusion: Extracranial SBRT in breast cancer patients with OMD or OPD was well-tolerated with excellent LC. SBRT should especially be offered to younger OMD and OPD breast cancer patients with only one metastasis. The increase in utilization since 2017 points toward a growing acceptance of SBRT for OMD and OPD in breast cancer.

A Validated T Cell Radiomics Score Is Associated With Clinical Outcomes Following Multisite SBRT and Pembrolizumab

PURPOSE

Combining immune checkpoint blockade (ICB) with stereotactic body radiation therapy (SBRT) may improve the local response to radiation and the systemic response to immunotherapy. However, no prognostic markers exist to identify patients likely to benefit from combined therapy. The degree of T cell-mediated immunity, which can be quantified with radiomics using computed tomography (CT) imaging, is predictive of immunotherapy response. Herein we investigated whether a validated T cell radiomics score (RS) is correlated with clinical outcomes after multisite SBRT and pembrolizumab (SBRT + P).

METHODS AND MATERIALS

The RS was quantified for 68 patients with metastatic treatment-refractory adult solid tumors who received SBRT (30-50 Gy, 3-5 fractions) and pembrolizumab ≤7 days after SBRT. RS was calculated using 8 variables, including 5 radiomics features extracted from pretreatment CT scans. At a prespecified cutoff of the 25th percentile, we assessed the association between RS and clinical outcomes. The Kaplan-Meier method was used to estimate survival outcomes. The prognostic effect of RS was assessed via logistic regression or Cox proportional hazards models. In an exploratory analysis, RS was also analyzed as a continuous variable.

RESULTS

One hundred thirty-nine tumors were analyzed. At the 25th percentile cutoff, high-RS patients were more likely to exhibit irradiated tumor responses to SBRT + P (odds ratio [OR] 10.2; 95% confidence interval [CI], 1.76-59.17; P = .012). High-RS was associated with improved TMC compared with low-RS tumors (hazard ratio [HR] 0.18; 95% CI, 0.04-0.74; P = .018). Furthermore, high-RS patients had improved PFS (HR 0.47, 95% CI, 0.26-0.85; P = .013) and OS (HR 0.39, 95% CI, 0.20-0.75; P = .005). As a continuous variable, higher RS was associated with improved PFS (HR 0.12, 95% CI, 0.03-0.51; P = .004) but did not reach statistical significance for TMC (HR 0.36, 95% CI, 0.02-7.02; P = .502) or OS (HR 0.28, 95% CI, 0.05-1.55; P = .144).

CONCLUSIONS

We demonstrated the clinical validity of RS (at the 25th percentile cutoff) as a prognostic biomarker in patients treated with SBRT + P. Future validation of the prognostic value of RS in larger similarly treated patient cohorts is warranted.