Stereotactic Body Radiotherapy Shows Promise for Oligometastatic Cancer Treatment Without Systemic Therapy
核心洞察
Metastasis-directed stereotactic body radiotherapy (搜索) (SBRT (搜索)) alone achieved a pooled 1- or 2-year systemic therapy-free survival rate of 69.7% across 13 studies with 2,074 patients.
Patients with oligometastatic prostate and renal cell cancers showed particularly strong outcomes, with STFS rates of 78.1% and 87.0% respectively.
The treatment demonstrated manageable toxicity with grade 3 or higher adverse events occurring in only 1.9% to 8.8% of patients across studies.
Metastasis-directed stereotactic body radiotherapy (搜索) (SBRT (搜索)) administered without immediate systemic therapy demonstrates clinically meaningful treatment deferral in patients with oligometastatic cancer (搜索), particularly those with prostate and renal cell cancers, according to a comprehensive systematic review and meta-analysis published in JAMA Network Open.
The analysis of 29 studies encompassing 2,074 unique patients revealed a pooled 1- or 2-year systemic therapy-free survival (STFS) rate of 69.7% (95% CI, 57.4%-80.8%). The findings suggest that SBRT (搜索) alone can effectively delay the need for systemic treatment while maintaining manageable toxicity profiles.
Cancer-Specific Outcomes Show Significant Variation
The meta-analysis revealed substantial differences in treatment outcomes across cancer types. Patients with renal cell cancer (搜索) achieved the highest STFS rate at 87.0% (95% CI, 76.2%-95.2%), followed by prostate cancer (搜索) patients at 78.1% (95% CI, 67.4%-87.3%). Other cancer types showed more modest results, with gynecological cancers achieving 66.3% STFS and sarcomas reaching 56.2%.
"In this systemic review and meta-analysis, metastasis-directed SBRT (搜索) without up-front systemic therapy was associated with clinically meaningful deferral of systemic treatment in patients with oligometastatic prostate and renal cell cancer (搜索)," wrote lead study author Jonas Willmann, MD, from the Department of Radiation Oncology at University Hospital Zurich (搜索). "This strategy was associated with a low incidence of severe adverse events, potentially preserving quality of life."
Meta-regression analysis indicated that histology accounted for 35.7% of between-study heterogeneity, highlighting the importance of cancer type in treatment outcomes. Among prostate cancer (搜索) studies, factors associated with longer STFS included prostate-specific antigen (搜索) (PSA (搜索)) levels, favorable response after SBRT (搜索), and shorter PSA doubling time.
Safety Profile Supports Clinical Implementation
The safety analysis across 20 studies demonstrated that SBRT (搜索) alone was well tolerated, with grade 3 or higher adverse events ranging from 1.9% to 8.8% among studies that observed severe adverse events. Notably, 15 of 19 studies reported no grade 3 or higher adverse effects. Quality of life assessments from six studies showed preserved QOL across disease sites following SBRT treatment.
Repeat SBRT (搜索) emerged as a viable treatment strategy for disease progression, with utilization rates varying by cancer type. In prostate cancer (搜索) studies, 16% to 42% of patients received repeat SBRT, while 44% of renal cell cancer (搜索) patients and 25% of sarcoma (搜索) patients underwent additional SBRT treatments.
Concurrent Biological Therapy Safety Confirmed
Complementing these findings, the Toxicity and Efficacy of Combined Stereotactic Radiotherapy and Systemic Targeted or Immune Therapy (TOaSTT) consortium conducted a prospective registry study examining the safety of combining metastases-directed stereotactic radiotherapy with modern biological cancer therapies. The study included 514 SRT treatments delivered to 433 patients across 27 centers.
The TOaSTT study found that severe adverse events remained uncommon when SRT was combined with biological therapies. Grade 3 or higher acute adverse events occurred in 5.3% of treatments, while severe late adverse events were observed in 6.3% of patients. Critically, continuing biological cancer therapies during SRT was not associated with a statistically significant increase in either acute or late severe adverse events (odds ratio 2.32; 95% CI 0.87-6.22).
Treatment Patterns and Patient Selection
The systematic review included studies published after January 2009 that investigated metastasis-directed SBRT (搜索) for oligometastatic cancer (搜索), defined as five or fewer metastases. The research encompassed both prospective and retrospective studies with at least 10 patients reporting relevant survival outcomes.
Freedom from metastases varied significantly across cancer types, with prostate cancer (搜索) patients achieving rates between 23% to 76%. Patients with soft tissue sarcoma (搜索) and bladder cancer showed lower rates at 6% and 23% respectively, while 38% of patients with other cancer types remained free from metastasis.
The TOaSTT registry study population had a median age of 62 years, with malignant melanoma (搜索) (37.0%) and non-small cell lung cancer (搜索) (35.8%) representing the most common primary tumors. Immune checkpoint inhibitors (搜索) were used in 61.3% of treatments, followed by small-molecule drugs (29.2%) and monoclonal antibodies (搜索) (9.5%).
Clinical Implications and Future Directions
The combined evidence from both studies supports the integration of metastasis-directed SBRT (搜索) into clinical practice for appropriately selected patients with oligometastatic disease. The treatment approach offers the potential to delay systemic therapy initiation while maintaining acceptable safety profiles, particularly important for preserving quality of life.
However, the authors emphasized the need for continued research to optimize treatment strategies. "Randomized clinical trials are needed to confirm outcomes and refine treatment strategies. Prognostic and predictive biomarkers should be explored to guide patient selection," the systematic review authors concluded.
The TOaSTT investigators similarly noted that while their findings provide reassurance for clinicians considering combined modality treatment, further prospective research is needed to refine safety profiles for specific drug-radiotherapy combinations and anatomical sites.