Progression-free survival and local control following stereotactic ablative radiotherapy for up to 5 oligometastases: an analysis from the population-based phase II SABR-5 trial

Immunotherapy-Boosted Stereotactic Ablative Radiotherapy in Inoperable Early-Stage Non-Small Cell Lung Cancer

OPINION STATEMENT

The combination of stereotactic ablative radiotherapy (SABR) with immune checkpoint inhibitors, known as iSABR, marks a significant evolution in treating early-stage, inoperable non-small cell lung cancer (NSCLC). Managing these cases requires a multidisciplinary approach involving radiation and medical oncologists. Clinical evidence from a meta-analysis of seven studies, including 462 patients, indicates that iSABR may offer better outcomes than SABR alone. The analysis showed significantly improved progression-free survival (PFS) rates at 1-, 2-, and 3-year follow-ups for iSABR compared to SABR. There was also a trend toward better overall survival (OS) with iSABR. Subgroup analyses highlighted enhanced 3-year PFS with programmed death-1 (PD-1) inhibitors and doses per fraction ≥ 12.5 Gy. While iSABR slightly increased the risk of grade ≥ 3 adverse events like pneumonitis, fatigue, and skin reactions, these risks are generally manageable within a multidisciplinary treatment framework. In conclusion, iSABR demonstrates potential benefits and manageable risks in phase I/II trials for early-stage, inoperable NSCLC, with improved PFS and acceptable toxicity. These findings warrant further investigation in a larger phase III prospective randomized controlled trial to validate efficacy, optimize protocols, and establish long-term safety.

1-year efficacy results after MR-guided risk-adapted stereotactic radiotherapy of infra-diaphragmatic oligometastases in a multicenter phase II trial

BACKGROUND AND PURPOSE

The SOFT (Stereotactic ablative radiotherapy of infra-diaphragmatic sOFT tissue metastases) trial assesses the safety and efficacy of risk-adapted MR-guided stereotactic ablative radiotherapy (SABR) of infra-diaphragmatic soft tissue metastasis in patients with oligometastatic disease (OMD) (clinicaltrials.gov ID NCT04407897). This paper reports the one-year efficacy analysis and evaluates associations between local control (LC) and clinical and dosimetric parameters.

MATERIALS AND METHODS

This investigator-initiated, multicenter, single-arm, phase 2 study recruited patients from four MR-linac centers in Denmark and the US. Patients with De novo or recurrent OMD with ≤5 metastases in ≤3 organs and patients with induced OMD or oligoprogressive disease (OPD) with ≤3 metastases were eligible. Fractionation schemes were 45-75 Gy in 3-8 fractions.

RESULTS

The trial included 121 patients with 147 oligometastatic lesions, primarily in the liver (41 %), lymph nodes (35 %), or adrenal glands (14 %). The median follow-up time was 13.0 months, interquartile range (IQR) (11.7,13.7) months. The 1-year LC rate was 89 %, 95 % confidence interval (CI) (83,94 %). We did not observe any statistically significant associations between LC and clinical and dosimetric parameters. The median progression-free survival was 7.1 months, 95 % CI (6.0,9.4). One- and two-year overall survival was 82.6 %, 95 % CI (76.2 %,89.7 %), and 65.1 %, 95 % CI (56.4 %,75.3 %). Sixty-one patients (50 %) were kept off systemic therapy throughout the one-year follow-up.

CONCLUSION

In our study, treatment with risk-adapted, MR-guided SABR resulted in a high one-year local control and survival rate and could keep half of the patients off systemic therapy within the first year of follow-up.

Stereotactic Magnetic Resonance Guided Adaptive Radiation Therapy for Infradiaphragmatic Oligometastatic Disease: Disrupting the One-Size-Fits-All Paradigm

PURPOSE

Although recent studies have demonstrated the benefits of stereotactic ablative radiotherapy (SABR) in the treatment of oligometastatic (OM) disease, toxicity remains a concern in the infradiaphragmatic region. This is largely because of challenges in soft tissue visualization, motion management, and the proximity of gastrointestinal organs at risk. Stereotactic magnetic resonance guided adaptive radiation therapy (SMART) may enhance the safety and efficacy of SABR in abdominopelvic targets.

METHODS AND MATERIALS

Patients with infradiaphragmatic OM disease, including up to 5 lesions treated with SMART between May 2018 and September 2023, were evaluated. Progression-free survival, overall survival, and local control (LC) were analyzed using Kaplan-Meier and Fine and Gray proportional subhazards models, whereas treatment-related toxicities were assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events v4.0 criteria.

RESULTS

One hundred eighty-three targets in 138 patients with primarily lung, colorectal, and noncolorectal gastrointestinal cancers were prescribed a median dose of 50 Gy in 5 fractions on a 0.35-T magnetic resonance-Linac. Overall, 62.8% of treated metastases were within 5 mm of a dose-limiting organs at risk, necessitating online adaptive planning in 670 of 875 (76.6%) delivered SABR fractions. The 1-year progression-free survival rate was 35.8% for the entire population and significantly differed between OM and oligoprogressive patients (42.4% vs 25.4%, P = .03). There was a trend toward lower LC in colorectal versus noncolorectal histology in the definitive dose group (biologically effective dose10 ≥ 75 Gy) with 2-year LC rates of 74.0% versus 86.0%, respectively, P = .08. Acute and late grade ≥3 toxicities were 0% and 2.2%, respectively.

CONCLUSIONS

SMART is feasible and effective for treating OM disease lesions in proximity to dose-limited organs at risk. Safe dose escalation is facilitated by online adaptive radiation therapy and is associated with long-term LC. Patient selection is key to identifying which patients with OM or oligoprogressive disease should be considered most appropriate for SMART.

Survival analysis of patients with metastatic head and neck squamous cell carcinoma treated with metastasis-directed radiotherapy and immunotherapy

OBJECTIVE

Immunotherapy combined with chemotherapy is currently the first-line treatment for metastatic head and neck squamous cell carcinoma (HNSCC). This study aims to evaluate whether adding metastasis-directed radiotherapy (MDRT) to immunotherapy and chemotherapy could improve the survival rate of patients with metastatic HNSCC.

MATERIALS AND METHODS

A retrospective analysis was conducted on patients with HNSCC who developed distant metastases after curative treatment. Systemic treatment was determined by the multidisciplinary team, with a programmed cell death-1 (PD-1) inhibitor combined with chemotherapy as the primary approach. The feasibility of radiotherapy was evaluated by clinical and imaging examinations. Stereotactic body radiotherapy (SBRT) was used to deliver different doses according to the number and location of metastatic lesions. Kaplan-Meier method was used to estimate survival, and Cox regression analysis was performed to evaluate the association between clinical factors and survival outcomes.

RESULTS

From January 2018 to June 2023, a total of 94 patients with 164 metastatic sites were included for the analysis. The most common primary tumor was the nasopharynx (77.7%), with the lung being the most frequent site of metastasis (46.8%), followed by bone (37.2%). Radiotherapy was administered to 276 metastatic lesions, with a median dose of 52.3 Gy (range: 24-60 Gy). The median overall survival (OS) was 43.0 months (range: 20.2-65.8). The OS rates at 2 and 5 years were 70.1% (95% CI, 59.7-80.5%) and 30.1% (95%CI 11.7-48.5%), respectively. Univariate and multivariate analysis showed that the number of metastases and the location of the primary tumor were significantly associated with OS.

CONCLUSIONS

In patients with metastatic HNSCC, MDRT combined with immunotherapy and chemotherapy can effectively improve local control and OS. These findings warrant further validation through prospective clinical trials.

The Impact of Ultracentral Tumor Location on Outcomes in Patients with Pulmonary Oligometastases: A Secondary Analysis of the Single-Arm Phase 2 SABR-5 Trial

PURPOSE/OBJECTIVES

There are limited data on outcomes in patients with ultracentral pulmonary oligometastases treated with SABR. The purpose of this study was to determine whether ultracentral location was prognostic for toxicity and survival.

MATERIAL AND METHODS

Oligometastatic lung lesions treated on the single-arm phase 2 SABR-5 trial were retrospectively stratified into 2 cohorts: ultracentral tumors (UC), defined as planning target volume overlap or direct tumor abutment to the proximal bronchial tree, esophagus, great vessels, or heart, and nonultracentral tumors. Cohorts were compared with respect to grade ≥ 2 toxicity, progression-free survival (PFS), and overall survival (OS).

RESULTS

In total, 41 patients with 45 ultracentral metastases and 93 patients with 172 nonultracentral metastases underwent SABR. The most common primary histologies were colorectal (30%), lung (13%), and renal (13%), and these did not differ between groups. Patients with UC had a lower median PFS of 5.8 months compared with 15.8 months in patients with non ultracentral tumors (P < .001). OS was also worse in the UC cohort: median 29.0 months versus not yet reached (P < .001). On multivariable regression, UC remained prognostic for worse PFS (hazard ratio 2.18, P = .004) and OS (hazard ratio 3.45, P < .001). Groups had similar rates of local tumor control. Patients with UC had higher 2-year cumulative incidence of polymetastatic progression: 69.2% versus 31.4% (P < .001). The 2-year cumulative incidence of grade ≥ 2 toxicity was 14.6% for patients with UC and 9.8% for patients with nonultracentral tumors (P = .74). There were no grade 4 or 5 toxicities.

CONCLUSIONS

In this prospective patient cohort, SABR for ultracentral tumor had low toxicity rates and good local control. However, ultracentral location was an adverse prognostic feature for survival. This finding should be validated with larger studies and may be a factor when weighing the benefit versus risk of SABR in patients with pulmonary oligometastases.

Metastasis-directed stereotactic radiotherapy in patients with breast cancer: results of an international multicenter cohort study

Metastasis-directed therapy (MDT) for oligometastatic breast cancer (≤ 5 metastases) has shown little effect in specific scenarios of randomized trials. Therefore, we aimed to assess outcomes after metastasis-directed stereotactic radiotherapy (SRT) in various clinical scenarios. We conducted an international retrospective cohort study in thirteen centers including breast cancer patients receiving SRT to any metastatic site. Outcomes included local recurrence (LR), progression-free survival (PFS), and overall survival (OS). Cumulative incidence analysis was used for LR, Kaplan-Meier estimates for PFS and OS. Covariables included patient, disease, and SRT characteristics. We performed univariable and multivariable analyses (MVA). Among 444 patients, 751 metastases were treated with SRT. Of these, 73% were intracranial and 27% extracranial lesions. Oligometastatic disease (OMD) was present in 66% of the patients. LR after two years occurred significantly more often in intracranial (25%) versus extracranial lesions (7%). In MVA of patients with OMD treated for intracranial sites, higher performance status was significantly associated with longer PFS. Further, higher performance status, biologic subtype (HR-pos./HER2-pos.), and MDT to all sites were significantly associated with longer OS. In MVA of oligometastatic patients treated for extracranial sites, biologic subtype (HR-neg./HER2-pos.) and synchronous metastasis were associated with significantly longer PFS, whereas higher grading was associated with significantly shorter PFS. Moreover, biologic subtype (HR-neg./HER2-neg.) was associated with significantly shorter OS. In conclusion, the role of MDT for breast cancer may vary per clinical scenario. Patients with OMD treated for intracranial lesions who had MDT to all sites showed superior OS. Our results should be validated prospectively.

Multidisciplinary Canadian consensus on the multimodal management of high-risk and radioactive iodine-refractory thyroid carcinoma

Most follicular cell-derived differentiated thyroid carcinomas are regarded as low-risk neoplasms prompting conservative therapeutic management. Here, we provide consensus recommendations reached by a multidisciplinary group of endocrinologists, medical oncologists, pathologists, radiation oncology specialists, a surgeon and a medication reimbursement specialist, addressing more challenging forms of this malignancy, focused on radioactive iodine (RAI)-resistant or -refractory differentiated thyroid carcinoma (RAIRTC). In this document we highlight clinical, radiographic, and molecular features providing the basis for these management plans. We distinguish differentiated thyroid cancers associated with more aggressive behavior from thyroid cancers manifesting as poorly differentiated and/or anaplastic carcinomas. Treatment algorithms based on risk-benefit assessments of different multimodal therapy approaches are also discussed. Given the scarcity of data supporting management of this rare yet aggressive disease entity, these consensus recommendations provide much needed guidance for multidisciplinary teams to optimally manage RAIRTC.

Cyclin-dependent kinase 4/6 inhibitors combined with stereotactic ablative radiotherapy in oligometastatic HR-positive/HER2-negative breast cancer patients

OBJECTIVES

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) have significantly improved the survival of patients with hormone receptor-positive HER2-negative advanced breast cancer (ABC). Although stereotactic ablative radiotherapy (SABR) is used more often in routine clinical practice, data on the safety and efficacy of combining SABR with CDK4/6i are lacking. Herein, we present the results of SABR combined with CDK4/6i in ABC.

METHODS

Patients with ABC who received CDK4/6i and SABR between 2018 and 2023 were analysed.

RESULTS

Among 384 patients treated with CDK4/6i, 34 patients received 44 courses of SABR. Two-year progression-free survival (PFS) was 63.6% (95% CI, 45.8-88.3), and the median PFS was 32 months. Three-year overall survival (OS) was 88.9% (95% CI, 77.7-100). Two-year local control (LC) was 92.7% (95% CI, 83.4-100). Median OS and LC were not reached. The subgroup analysis showed the difference in survival between oligometastatic patients (OMD) and non-OMD subgroup. Two-year PFS was 69.2% (95% CI, 44.5-100) in OMD compared with 57.4% (95% CI, 36-91.7) in the non-OMD (P = .042). Three-year OS was 90% (95% CI, 73.2-100) in OMD compared with 86.2% (95% CI, 70-100) in the non-OMD (P = .67). Median PFS and OS in the non-OMD were 26 and 56 months, respectively, and were not reached in OMD. Fifteen patients required CDK4/6i dose reduction, and 2 discontinued treatment due to toxicity. No difference in high-grade toxicity was observed between the sequential and concurrent SABR.

CONCLUSION

The addition of SABR to CDK4/6i seems to be safe and effective, especially in patients with oligometastatic disease.

ADVANCES IN KNOWLEDGE

In advanced breast cancer patients treated with CDK4/6i, SABR provides a high local control and may provide additional benefit in an oligometastatic setting.

Systematic review of the efficacy of stereotactic ablative radiotherapy for oligoprogressive disease in metastatic cancer

BACKGROUND

Stereotactic Ablative Radiotherapy (SABR) for the treatment of oligometastatic disease can improve survival and delay the requirement for systemic therapy. The benefits of SABR in oligoprogressive disease are less well-defined. Here, we evaluate the available evidence investigating the efficacy of SABR in the treatment of oligoprogressive disease.

METHODS

A systematic review was carried out following PRISMA guidelines. Medline and Embase databases were searched using the terms "stereotactic radiotherapy" OR "SABR" OR "Stereotactic Ablative Body Radiotherapy" OR "SBRT" OR "SRT" AND "oligoprogression" in May 2022, June 2023, and February 2024. Studies were excluded where: SABR was used as a radical treatment, a specific oligoprogressive cohort could not be identified, publication was as a conference abstract or where fewer than 10 patients were recruited. Studies treating only brain metastases were also excluded. The site of primary tumour, oligoprogressive sites, rates of overall survival (OS), progression free survival (PFS), local control (LC) and time to next systemic therapy were collected.

RESULTS

Thirty-three full text studies were included. These consisted of single centre and multi-institutional observational studies, case series and phase II trials. Twenty-two studies were related to a specific tumour type: 12 urological cancer (9 prostate, 3 renal cancer), 6 non-small cell lung cancer, 2 colorectal cancer, 2 breast cancer and 11 were studies covering multiple tumour sites (5 studies involving SABR to a single organ and 6 studies involving SABR to multi-organ). Median PFS was >6 months in patients with oligoprogressive prostate, non-small cell lung cancer and renal cancer patients.

CONCLUSIONS

SABR appears to have clinical benefit in oligoprogresssive prostate, lung, and renal patients. However, the optimal management of patients with oligoprogressive disease is still somewhat uncertain due to lack of prospective data. This will hopefully become clearer in the near future with the publication of further randomised trials.

Upfront Versus Delayed Systemic Therapy in Patients With Oligometastatic Cancer Treated With SABR in the Phase 2 SABR-5 Trial

PURPOSE

The optimal sequencing of local and systemic therapy for oligometastatic cancer has not been established. This study retrospectively compared progression-free survival (PFS), overall survival (OS), and SABR-related toxicity between upfront versus delay of systemic treatment until progression in patients in the SABR-5 trial.

METHODS AND MATERIALS

The single-arm phase 2 SABR-5 trial accrued patients with up to 5 oligometastases across SABR-5 between November 2016 and July 2020. Patients received SABR to all lesions. Two cohorts were retrospectively identified: those receiving upfront systemic treatment along with SABR and those for whom systemic treatment was delayed until disease progression. Patients treated for oligoprogression were excluded. Propensity score analysis with overlap weighting balanced baseline characteristics of cohorts. Bootstrap sampling and Cox regression models estimated the association of delayed systemic treatment with PFS, OS, and grade ≥2 toxicity.

RESULTS

A total of 319 patients with oligometastases underwent treatment on SABR-5, including 121 (38%) and 198 (62%) who received upfront and delayed systemic treatment, respectively. In the weighted sample, prostate cancer was the most common primary tumor histology (48%) followed by colorectal (18%), breast (13%), and lung (4%). Most patients (93%) were treated for 1 to 2 metastases. The median follow-up time was 34 months (IQR, 24-45). Delayed systemic treatment was associated with shorter PFS (hazard ratio [HR], 1.56; 95% CI, 1.15-2.13; P = .005) but similar OS (HR, 0.90; 95% CI, 0.51-1.59; P = .65) compared with upfront systemic treatment. Risk of grade 2 or higher SABR-related toxicity was reduced with delayed systemic treatment (odds ratio, 0.35; 95% CI, 0.15-0.70; P < .001).

CONCLUSIONS

Delayed systemic treatment is associated with shorter PFS without reduction in OS and with reduced SABR-related toxicity and may be a favorable option for select patients seeking to avoid initial systemic treatment. Efforts should continue to accrue patients to histology-specific trials examining a delayed systemic treatment approach.

Stereotactic body radiotherapy for distant metastases to the head and neck

PURPOSE

To report clinical outcomes for patients with metastatic disease to the head and neck (HN) treated with stereotactic body radiation therapy (SBRT).

METHODS

A retrospective review of patients treated with SBRT to HN sites from 2012 to 2020 was conducted. Treatment indications included the following: oligometastases, oligoprogression, and control a dominant area of progression (DAP). Kaplan-Meier method was used to estimate local control (LC), regional control (RC), overall survival (OS), and progression-free survival (PFS). Univariable (UVA) and multivariable analyses (MVA) were performed. Grade 3-4 acute and late toxicities were reported by the Common Terminology Criteria for Adverse Events v5.0.

RESULTS

Fifty-six patients (58 lesions) were analysed with a median follow-up of 16 months. Primary sites included lung (25.0%), kidney (19.6%), breast (19.6%) and other (35.8%). SBRT indications were as follows: oligometastases (42.9%), oligoprogression (19.6%) and local control of a dominant area of progression (37.5%). Most patients received SBRT to a single neck node (n = 47, 81.0%). Median SBRT dose was 40 Gy (range 25-50 Gy) in five fractions, with a median biologically effective dose (BED10) of 72 Gy (range 37.5-100 Gy). One- and 2-year LC and RC rates were 97.6% and 72.7% as well as 100% and 86.7%, respectively. Median OS was 19.2 months (95% [CI] 14.8-69.4), and median PFS was 7.4 months (95% [CI] 5.2-11.9). The 1-year OS and PFS rates for oligometastases, oligoprogression and DAP were 95.8%, 63.6% and 38.1% (p = 0.0039) as well as 56.5%, 27.3% and 19.1% (p = 0.0004), respectively. On MVA, treatment indication and histology were predictive for OS, while indication and prior systemic therapy were predictive for PFS. Cumulative late grade 3 + toxicity rate was 11.3%, without grade 5 events.

CONCLUSION

The use of SBRT for metastatic disease to the HN provided excellent LC rates with low rates of regional failure and an acceptable toxicity profile, highlighting its utility in these patients. Patients with oligometastatic disease had better OS and PFS than others.

Prospective Longitudinal Assessment of Quality of Life After Stereotactic Ablative Radiotherapy for Oligometastases: Analysis of the Population-based SABR-5 Phase II Trial

AIMS

To evaluate longitudinal patient-reported quality of life (QoL) in patients treated with stereotactic ablative radiotherapy (SABR) for oligometastases.

MATERIALS AND METHODS

The SABR-5 trial was a population-based single-arm phase II study of SABR to up to five sites of oligometastases, conducted in six regional cancer centres in British Columbia, Canada from 2016 to 2020. Prospective QoL was measured using treatment site-specific QoL questionnaires at pre-treatment baseline and at 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after treatment. Patients with bone metastases were assessed with the Brief Pain Inventory (BPI). Patients with liver, adrenal and abdominopelvic lymph node metastases were assessed with the Functional Assessment of Chronic Illness Therapy-Abdominal Discomfort (FACIT-AD). Patients with lung and intrathoracic lymph node metastases were assessed with the Prospective Outcomes and Support Initiative (POSI) lung questionnaire. The two one-sided test procedure was used to assess equivalence between the worst QoL score and the baseline score of individual patients. The mean QoL at all time points was used to determine the trajectory of QoL response after SABR. The proportion of patients with 'stable', 'improved' or 'worsened' QoL was determined for all time points based on standard minimal clinically important differences (MCID; BPI worst pain = 2, BPI functional interference score [FIS] = 0.5, FACIT-AD Trial Outcome Index [TOI] = 8, POSI = 3).

RESULTS

All enrolled patients with baseline QoL assessment and at least one follow-up assessment were analysed (n = 133). On equivalence testing, the patients' worst QoL scores were clinically different from baseline scores and met MCID (BPI worst pain mean difference: 1.8, 90% confidence interval 1.19 to 2.42]; BPI FIS mean difference: 1.68, 90% confidence interval 1.15 to 2.21; FACIT-AD TOI mean difference: -8.76, 90% confidence interval -11.29 to -6.24; POSI mean difference: -4.61, 90% confidence interval -6.09 to -3.14). However, the mean FIS transiently worsened at 9, 18 and 21 months but eventually returned to stable levels. The mean FACIT and POSI scores also worsened at 36 months, albeit with a limited number of responses (n = 4 and 8, respectively). Most patients reported stable QoL at all time points (range: BPI worst pain 71-82%, BPI FIS 45-78%, FACIT-AD TOI 50-100%, POSI 25-73%). Clinically significant stability, worsening and improvement were seen in 70%/13%/18% of patients at 3 months, 53%/28%/19% at 18 months and 63%/25%/13% at 36 months.

CONCLUSIONS

Transient decreases in QoL that met MCID were seen between patients' worst QoL scores and baseline scores. However, most patients experienced stable QoL relative to pre-treatment levels on long-term follow-up. Further studies are needed to characterise patients at greatest risk for decreased QoL.

Predictors of Quality of Life Decline in Patients with Oligometastases treated with Stereotactic Ablative Radiotherapy: Analysis of the Population-Based SABR-5 Phase II Trial

AIMS

Most patients experience stable quality of life (QoL) after stereotactic ablative radiotherapy (SABR) treatment for oligometastases. However, a subset of patients experience clinically relevant declines in QoL on post-treatment follow-up. This study aimed to identify risk factors for QoL decline.

MATERIALS AND METHODS

The SABR-5 trial was a population-based single-arm phase II study of SABR to up to five sites of oligometastases. Prospective QoL was measured using treatment site-specific tools at pre-treatment baseline and 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after treatment. The time to persistent QoL decline was calculated as the time from SABR to the first decline in QoL score meeting minimum clinically important difference with no improvement to baseline score on subsequent assessments. Univariable and multivariable logistic regression analyses were carried out to determine factors associated with QoL decline.

RESULTS

One hundred and thirty-three patients were included with a median follow-up of 32 months (interquartile range 25-43). Thirty-five patients (26%) experienced a persistent decline in QoL. The median time until persistent QoL decline was not reached. The cumulative incidence of QoL decline at 2 and 3 years were 22% (95% confidence interval 14.0-29.6) and 40% (95% confidence interval 28.0-51.2), respectively. In multivariable analysis, disease progression (odds ratio 5.23, 95% confidence interval 1.59-17.47, P = 0.007) and adrenal metastases (odds ratio 9.70, 95% confidence interval 1.41-66.93, P = 0.021) were associated with a higher risk of QoL decline. Grade 3 or higher (odds ratio 3.88, 95% confidence interval 0.92-16.31, P = 0.064) and grade 2 or higher SABR-associated toxicity (odds ratio 2.24, 95% confidence interval 0.85-5.91, P = 0.10) were associated with an increased risk of QoL decline but did not reach statistical significance.

CONCLUSIONS

Disease progression and adrenal lesion site were associated with persistent QoL decline following SABR. The development of grade 3 or higher toxicities was also associated with an increased risk, albeit not statistically significant. Further studies are needed, focusing on the QoL impact of metastasis-directed therapies.

Stereotactic Body Radiotherapy for Extracranial Oligometastatic Disease from Head and Neck Primary Cancers: A Systematic Review and Meta-Analysis

INTRODUCTION

Stereotactic body radiotherapy (SBRT) is increasingly used to treat disease in the oligometastatic (OM) setting due to mounting evidence demonstrating its efficacy and safety. Given the low population representation in prospective studies, we performed a systematic review and meta-analysis of outcomes of HNC patients with extracranial OM disease treated with SBRT.

METHODS

A systematic review was conducted with Cochrane, Medline, and Embase databases queried from inception to August 2022 for studies with extracranial OM HNC treated with stereotactic radiotherapy. Polymetastatic patients (>five lesions), mixed-primary cohorts failing to report HNC separately, lack of treatment to all lesions, nonquantitative endpoints, and other definitive treatments (surgery, conventional radiotherapy, and radioablation) were excluded. The meta-analysis examined the pooled effects of 12- and 24-month local control (LC) per lesion, progression-free survival (PFS), and overall survival (OS). Weighted random-effects were assessed using the DerSimonian and Laird method, with heterogeneity evaluated using the I2 statistic and Cochran Qtest. Forest plots were generated for each endpoint.

RESULTS

Fifteen studies met the inclusion criteria (639 patients, 831 lesions), with twelve eligible for quantitative synthesis with common endpoints and sufficient reporting. Fourteen studies were retrospective, with a single prospective trial. Studies were small, with a median of 32 patients (range: 6-81) and 63 lesions (range: 6-126). The OM definition varied, with a maximum of two to five metastases, mixed synchronous and metachronous lesions, and a few studies including oligoprogressive lesions. The most common site of metastasis was the lung. Radiation was delivered in 1-10 fractions (20-70 Gy). The one-year LC (LC1), reported in 12 studies, was 86.9% (95% confidence interval [CI]: 79.3-91.9%). LC2 was 77.9% (95% CI: 66.4-86.3%), with heterogeneity across studies. PFS was reported in five studies, with a PFS1 of 43.0% (95% CI: 35.0-51.4%) and PFS2 of 23.9% (95% CI: 17.8-31.2%), with homogeneity across studies. OS was analyzed in nine studies, demonstrating an OS1 of 80.1% (95% CI: 74.2-85.0%) and OS2 of 60.7% (95% CI: 51.3-69.4%). Treatment was well tolerated with no reported grade 4 or 5 toxicities. Grade 3 toxicity rates were uniformly below 5% when reported.

CONCLUSIONS

SBRT offers excellent LC and promising OS, with acceptable toxicities in OM HNC. Durable PFS remains rare, highlighting the need for effective local or systemic therapies in this population. Further investigations on concurrent and adjuvant therapies are warranted.

Single vs. multiple fraction non-inferiority trial of stereotactic ablative radiotherapy for the comprehensive treatment of oligo-metastases/progression: SIMPLIFY-SABR-COMET

BACKGROUND

Radiotherapy delivery regimens can vary between a single fraction (SF) and multiple fractions (MF) given daily for up to several weeks depending on the location of the cancer or metastases. With limited evidence comparing fractionation regimens for oligometastases, there is support to explore toxicity levels to nearby organs at risk as a primary outcome while using SF and MF stereotactic ablative radiotherapy (SABR) as well as explore differences in patient-reported quality of life and experience.

METHODS

This study will randomize 598 patients in a 1:1 ratio between the standard arm (MF SABR) and the experimental arm (SF SABR). This trial is designed as two randomized controlled trials within one patient population for resource efficiency. The primary objective of the first randomization is to determine if SF SABR is non-inferior to MF SABR, with respect to healthcare provider (HCP)-reported grade 3-5 adverse events (AEs) that are related to SABR. Primary endpoint is toxicity while secondary endpoints include lesional control rate (LCR), and progression-free survival (PFS). The second randomization (BC Cancer sites only) will allocate participants to either complete quality of life (QoL) questionnaires only; or QoL questionnaires and a symptom-specific survey with symptom-guided HCP intervention. The primary objective of the second randomization is to determine if radiation-related symptom questionnaire-guided HCP intervention results in improved reported QoL as measured by the EuroQoL-5-dimensions-5levels (EQ-5D-5L) instrument. The primary endpoint is patient-reported QoL and secondary endpoints include: persistence/resolution of symptom reporting, QoL, intervention cost effectiveness, resource utilization, and overall survival.

DISCUSSION

This study will compare SF and MF SABR in the treatment of oligometastases and oligoprogression to determine if there is non-inferior toxicity for SF SABR in selected participants with 1-5 oligometastatic lesions. This study will also compare patient-reported QoL between participants who receive radiation-related symptom-guided HCP intervention and those who complete questionnaires alone.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT05784428. Date of Registration: 23 March 2023.

SBRT for Liver Tumors: What the Interventional Radiologist Needs to Know

This review summarizes the clinical evidence supporting the utilization of stereotactic body radiotherapy (SBRT) for liver tumors, including hepatocellular carcinoma, liver metastases, and cholangiocarcinoma. Emerging prospective evidence has demonstrated the benefit and low rates of toxicity across a broad range of clinical contexts. We provide an introduction for the interventional radiologist, with a discussion of underlying themes such as tumor dose-response, mitigation of liver toxicity, and the technical considerations relevant to performing liver SBRT. Ultimately, we recommend that SBRT should be routinely included in the armamentarium of locoregional therapies for liver malignancies, alongside those liver-directed therapies offered by interventional radiology.

Survival and relapse patterns in patients of cranial vs extra-cranial oligometastases treated with stereotactic radiosurgery/stereotactic body radiation therapy and systemic therapy

Objectives

To evaluate the outcome of patients with cranial (C) and extra-cranial (EC) oligometastases treated with stereotactic radiosurgery (SRS)/stereotactic body radiotherapy (SBRT) and standard of care systemic therapy.

Methods

During the period 2018-2022, patients who received SBRT or SRS for oligometastases (≤5 lesions) in addition to systemic therapy were evaluated. PET-CT was done to categorize them as C or EC oligometastases. Local control, distant progression, progression-free survival (PFS), overall survival (OS), and toxicity of the treatment were recorded.

Results

43 patients received SBRT/SRS to 88 oligometastatic lesions. Eighteen patients had C metastases, 23 had EC metastases and 2 patients had both. 40/43 patients had received systemic therapy. At a median follow-up of 13 months, median PFS was 14 months and 1 and 2 years OS was 83.2% and 67.4%. Local control with SRS was 92.8% and with SBRT was 86.3%. Distant failure in C vs EC oligometastases was seen in 12/14 vs 7/20 patients (P = 0.03). Median PFS was 30 months for EC and 6 months for C oligometastases (P = 0.003). 1 and 2 years OS was 89.6% and 82.7% for EC and 77.6% and 48.5% for C oligometastases (P = 0.21). One patient had grade 3 and 3 patients had grade 1 toxicity.

Conclusions

SRS and SBRT yielded high rates of local control with low toxicity. Compared to EC, patients with C oligometastases had higher distant relapses, poorer PFS, and a trend towards worse survival. More studies with separate enrolment of patients with C and EC oligometastases are needed.

Advances in knowledge

Outcome of patients with C oligometastases is poorer than EC metastases and hence the studies should be separately done in these 2 groups to assess the benefit of SRS/SBRT.

Long-term disease-free survival following comprehensive involved site radiotherapy for oligometastases

Introduction

Despite recent advances in drug development, durable complete remissions with systemic therapy alone for metastatic cancers remain infrequent. With the development of advanced radiation technologies capable of selectively sparing normal tissues, patients with oligometastases are often amenable to comprehensive involved site radiotherapy with curative intent. This study reports the long-term outcomes and patterns of failure for patients treated with total metastatic ablation often in combination with systemic therapy.

Materials and methods

Consecutive adult patients with oligometastases from solid tumor malignancy treated by a single high volume radiation oncologist between 2014 and 2021 were retrospectively analyzed. Oligometastases were defined as 5 or fewer metastatic lesions where all sites of active disease are amenable to local treatment. Comprehensive involved site radiotherapy consisted of stereotactic radiotherapy to a median dose of 27 Gy in 3 fractions and intensity modulated radiation therapy to a median dose of 50 Gy in 15 fractions. This study analyzed overall survival, progression-free survival, patterns of failure and toxicity.

Results

A total of 130 patients with 209 treated distant metastases were treated with a median follow-up of 36 months. The 4-year overall survival, progression-free survival, local control and distant control was 41%, 23%, 86% and 29%. Patterns of failure include 23% alive and free of disease (NED), 52% distant failure only, 9% NED but death from comorbid illness, 7% both local and distant failure, 4% NED but lost to follow-up, 4% referred to hospice before restaging, 1% local only failure, 1% alive with second primary cancer. Late grade 3+ toxicities occurred in 4% of patients, most commonly radionecrosis.

Conclusion

Involved site radiotherapy to all areas of known disease can safely achieve durable complete remissions in patients with oligometastases treated in the real world setting. Distant failures account for the majority of treatment failures and isolated local failures are exceedingly uncommon. Oligometastases represents a promising setting to investigate novel therapeutics targeting minimal residual disease.

Outcomes for oligometastatic head and neck cancer treated with stereotactic body radiotherapy: Results from an international multi-institutional consortium

BACKGROUND

We report the results of an international multi-institutional cohort of oligometastatic (OMD) head and neck cancer (HNC) patients treated with SBRT.

METHODS

Patients with OMD HNC (≤5 metastases) treated with SBRT between 2008 and 2016 at six institutions were included. Treated metastasis control (TMC), progression-free survival (PFS), and overall survival (OS) were analyzed by multivariable analysis (MVA).

RESULTS

Forty-two patients with 84 HNC oligometastases were analyzed. The TMC rate at 1 and 2 years were 80% and 66%, with a median time to recurrence of 10.1 months. The median PFS and OS were 4.7 and 23.3 months. MVA identified a PTV point maximum (BED)10 > 100 Gy as a predictor of improved TMC (HR = 0.31, p = 0.034), and a cumulative PTV > 48 cc as having worse PFS (HR = 2.99, p < 0.001).

CONCLUSION

Favorable TMC and OS was observed in OMD HNCs treated with SBRT.

Ablative radiotherapy improves survival but does not cure autochthonous mouse models of prostate and colorectal cancer

BACKGROUND

Genetically engineered mouse models (GEMMs) of cancer are powerful tools to study mechanisms of disease progression and therapy response, yet little is known about how these models respond to multimodality therapy used in patients. Radiation therapy (RT) is frequently used to treat localized cancers with curative intent, delay progression of oligometastases, and palliate symptoms of metastatic disease.

METHODS

Here we report the development, testing, and validation of a platform to immobilize and target tumors in mice with stereotactic ablative RT (SART). Xenograft and autochthonous tumor models were treated with hypofractionated ablative doses of radiotherapy.

RESULTS

We demonstrate that hypofractionated regimens used in clinical practice can be effectively delivered in mouse models. SART alters tumor stroma and the immune environment, improves survival in GEMMs of primary prostate and colorectal cancer, and synergizes with androgen deprivation in prostate cancer. Complete pathologic responses were achieved in xenograft models, but not in GEMMs.

CONCLUSIONS

While SART is capable of fully ablating xenografts, it is unable to completely eradicate disease in GEMMs, arguing that resistance to potentially curative therapy can be modeled in GEMMs.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Radiation and immune checkpoint inhibitors in the treatment of oligometastatic non-small-cell lung cancer: a practical review of rationale, recent data, and research questions

The combined use of stereotactic ablative radiotherapy (SABR) and immune checkpoint inhibitors (ICIs) is an emerging treatment paradigm for oligometastatic non-small-cell lung cancer (NSCLC). Recent phase I and II trial data suggest that SABR to multiple metastases in addition to ICI use is safe and effective with promising progression-free survival and overall survival signals. There is great interest in capitalizing on combined immunomodulation from these two modalities for the treatment of oligometastatic NSCLC. Ongoing trials seek to validate the safety, efficacy, and preferred sequencing of SABR and ICI. This narrative review of the role of SABR when combined with ICI in oligometastatic NSCLC discusses the rationale for this bimodality treatment, summarizes recent clinical trial evidence, and proposes key principles of management based on the available evidence.

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.

Top Ten Lessons Learned from Trials in Oligometastatic Cancers

Recent evidence supports the role of aggressive local treatment in the oligometastatic setting. In this review, we discuss the top 10 lessons we have learned from trials in oligometastatic cancers. Major lessons learned pertain to definitions of oligometastatic disease, outcomes, toxicity, costs, and the combination of ablative therapies with systemic therapy, including immunotherapy. Barriers to accrual for trials and upcoming phase III trials are also reviewed. These lessons may help to inform clinical practice and may be the basis for future research in the oligometastatic space.

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.