What is the role of stereotactic body radiotherapy (SBRT) in oligometastatic lung cancer?

For patients with oligometastatic NSCLC, adding SBRT to all sites of disease (primary tumor and metastases) to standard systemic therapy improves progression-free survival (PFS) and may improve overall survival (OS) compared with systemic therapy alone. The ASTRO/ESTRO guideline recommends local consolidative therapy, including SBRT, for all metastatic sites in patients with controlled primary tumors and ≤5 metastases ^[2]A1c. A systematic review of consolidative radiotherapy in oligometastatic and oligoprogressive NSCLC reported improved PFS and OS when SBRT was integrated with systemic therapy, although effect sizes varied across studies and were not pooled ^[4]D5. In a separate meta-analysis of SBRT for colorectal lung oligometastases (a distinct histology), pooled 1- and 2-year local control rates were 83.1% and 69.3%, respectively ^[5]B2a, but these data are from a different primary tumor and not directly applicable to NSCLC. The overall strength of evidence is moderate, supported by guideline-level recommendations ^[2]A1c and systematic reviews ^[4]D5, but definitive phase III data in the NSCLC-specific oligometastatic setting remain limited.

Pearl: SBRT to all oligometastatic sites plus standard systemic therapy is the guideline-recommended standard of care for oligometastatic NSCLC, based on improved PFS (moderate evidence); OS benefit is suggested but not yet proven in dedicated phase III NSCLC trials ^[2]A1c[4]D5.

The treatment paradigm for oligometastatic NSCLC has shifted over the past decade from systemic therapy alone to the routine incorporation of local ablative therapy, including stereotactic body radiotherapy ( SBRT ). Historically, patients with metastatic NSCLC were managed exclusively with systemic therapy (chemotherapy, targeted therapy, or immunotherapy), with local interventions reserved for palliation of symptoms. The concept of an oligometastatic state, an intermediate disease stage with limited metastatic spread, gained traction after early randomized trials demonstrated that adding local consolidative therapy to systemic treatment improved progression-free survival (PFS) and, in some cases, overall survival (OS) ^[2]A1c[4]D5. These findings prompted a re-evaluation of treatment goals, shifting from purely palliative to potentially curative-intent approaches for selected patients.

Landmark Evidence and Guideline Adoption

The pivotal evidence that changed practice came from randomized phase II trials (e.g., Gomez et al., 2016; Iyengar et al., 2018), which showed that local consolidative therapy (surgery or SBRT) to all sites of disease significantly prolonged PFS compared with maintenance systemic therapy or observation alone. Although these specific trials are not among the provided references, their conclusions are reflected in the ASTRO/ESTRO clinical practice guideline, which recommends SBRT as a definitive local therapy for oligometastatic NSCLC based on systematic review of the literature ^[2]A1c. The guideline emphasizes that comprehensive treatment of all known cancer, primary tumor, regional nodes, and metastases, with curative intent is now standard for appropriate candidates ^[2]A1c.

Abandoned Approaches and Technique Refinement

Prior to this paradigm shift, conventional fractionated radiotherapy was used for palliation but offered inferior local control and higher toxicity compared with SBRT. SBRT delivers high-dose, precisely targeted radiation in 1-5 fractions, achieving local control rates exceeding 80% at 1-2 years with low rates of grade ≥3 toxicity ^[1]A1c[7]A1b. The SAFRON II randomized trial confirmed that single-fraction SBRT is as safe and effective as multifraction regimens for pulmonary oligometastases, further simplifying treatment delivery ^[7]A1b. Consequently, older palliative radiotherapy schedules have been largely abandoned in favor of SBRT for patients with oligometastatic NSCLC who meet selection criteria (e.g., ≤5 metastases, good performance status, controlled primary) ^[2]A1c.

Pearl: The evolution from systemic therapy alone to combined-modality treatment with SBRT for oligometastatic NSCLC was driven by randomized evidence showing improved PFS, leading to guideline recommendations that now define SBRT as a standard-of-care local ablative option for eligible patients ^[2]A1c[4]D5.

The ASTRO/ESTRO clinical practice guideline recommends SBRT as a local therapy option for patients with oligometastatic NSCLC, with the goal of definitive treatment of all known disease ^[2]A1c. This recommendation is supported by systematic reviews demonstrating improved progression-free survival (PFS) and overall survival (OS) when consolidative SBRT is added to systemic therapy ^[4]D5. The International Stereotactic Radiosurgery Society (ISRS) practice guideline also endorses SBRT for pulmonary oligometastases, reporting high local control rates ^[1]A1c.

Key evidence includes a multicenter phase 2 study of durvalumab plus chemotherapy and SABR in oligometastatic NSCLC, which showed promising efficacy ^[11]C4. The TROG 13.01 SAFRON II trial established that single-fraction SABR is non-inferior to multifraction SABR for pulmonary oligometastases, with comparable safety and efficacy ^[7]A1b. For patients with oligoprogressive disease, consolidative radiotherapy (including SBRT) improves outcomes ^[4]D5.

Guidelines emphasize careful patient selection: those with 1-5 metastases, controlled primary, and good performance status derive the most benefit ^[2]A1c. SBRT achieves local control rates exceeding 80% at 1-2 years ^[1]A1c[5]B2a. Integration with immunotherapy or targeted therapy is an area of active investigation ^[11]C4[12]D5.

Pearl: SBRT is a standard local ablative therapy for oligometastatic NSCLC, with guideline recommendations and evidence from systematic reviews showing improved PFS and OS when combined with systemic therapy ^[2]A1c[4]D5.

The evidence supporting SBRT in oligometastatic NSCLC is derived largely from phase II trials, retrospective series, and meta-analyses that include heterogeneous primary histologies ^{[1]A1c[2]A1c[16]B2a}. The strongest data come from the SABR -COMET trial, which included a minority of NSCLC patients (18 of 99) ^[2]A1c. Direct extrapolation to all NSCLC histologies, particularly those with oncogene-driven disease or high PD-L1 expression, is limited by under-representation in these studies ^{[2]A1c[16]B2a}.

Patient Selection Criteria

Candidate selection is critical. The ASTRO/ESTRO guideline recommends SBRT for patients with ≤5 metastatic lesions and controlled primary tumor ^[2]A1c. Performance status ( ECOG 0-2) and adequate organ function are prerequisites ^{[2]A1c[16]B2a}. Patients with synchronous oligometastases (≤3 months from initial diagnosis) and metachronous oligometastases (>3 months) show similar benefit, but those with rapid progression on systemic therapy have poorer outcomes ^[2]A1c.

Histology and Molecular Subtype

NSCLC subtypes (adenocarcinoma, squamous cell carcinoma) have been included, but response to SBRT may be influenced by biology. For example, colorectal cancer pulmonary oligometastases treated with SBRT have a pooled 2-year local control of 69.3% (95% CI 64.8-73.8), which is lower than that typically reported for NSCLC lung metastases (≥80%) ^{[5]B2a[15]B2a}. Whether this difference is due to histology or prior systemic therapy is unclear. Patients with EGFR mutations or ALK rearrangements may achieve prolonged systemic control with targeted therapy, potentially altering the risk-benefit of SBRT ^{[2]A1c[16]B2a}. No prospective trials have specifically addressed SBRT in oncogene-driven NSCLC.

Tumor Location and Risks

Central lung tumors (within 2 cm of the proximal bronchial tree) carry increased risk of bronchial stricture, hemoptysis, and fistula ^[1]A1c[7]A1b. The SAFRON II trial safely used single- and multifraction SABR for peripheral lung metastases, but central lesions were excluded ^[7]A1b. For ultracentral lesions, SBRT is relatively contraindicated ^[1]A1c.

Cost-Effectiveness

SBRT for oligometastatic NSCLC appears cost-effective compared to standard care in modeling studies, with incremental cost-effectiveness ratios below $50,000 per quality-adjusted life year ^[14]B2c. However, these analyses depend on assumptions about survival benefit and are sensitive to patient selection ^[14]B2c.

Dissenting Evidence

One meta-analysis of colorectal cancer pulmonary oligometastases reported a 2-year local control of only 66.3% (95% CI 59.3-73.3) with SBRT, which is lower than that for NSCLC, suggesting that histology may modify benefit ^[15]B2a. Another systematic review of SBRT for oligoprogressive disease found limited prospective data; the only randomized trial (N=29) showed no significant improvement in progression-free survival (HR 0.95, 95% CI 0.50-1.79) ^[13]B2a.

Pearl: SBRT for oligometastatic NSCLC is best supported for patients with ≤5 metastases, controlled primary, good performance status, and peripheral lung lesions; the evidence is weaker for central tumors, rapid progression, and non-NSCLC histologies, where local control may be inferior ^{[1]A1c[2]A1c[5]B2a[15]B2a}.

Several ongoing and recently reported trials are poised to refine the role of SBRT in oligometastatic NSCLC. The multicenter, phase 2 AUSTRAL trial is evaluating the addition of durvalumab plus ceralasertib (an ATR inhibitor) to radiotherapy in stage III NSCLC patients who develop thoracic relapses and/or oligometastases after the PACIFIC regimen ^[12]D5. This study targets the common pattern of locoregional failure with limited metastatic burden, testing a novel radiosensitizer-immunotherapy combination in an off-protocol population ^[12]D5.

A separate multicenter phase 2 single-arm study ^[11]C4 has reported early results combining durvalumab, platinum-doublet chemotherapy, and SABR in chemotherapy-naïve oligometastatic stage IV NSCLC (driver-gene negative). The primary endpoint is progression-free survival (PFS); the full efficacy and safety results await peer-reviewed publication but signal potential for a quadruple-modality approach without prior systemic therapy ^[11]C4.

For evidence emerging in broader oligometastatic populations, two meta-analyses comparing SBRT to surgery or thermal ablation for colorectal lung metastases have shown comparable 1- and 3-year local control and overall survival, though NSCLC-specific data remain limited ^[3]B2a[8]B2a. A network meta-analysis found surgery and SBRT ranked similarly for overall survival in colorectal pulmonary metastases, but the comparison has not been replicated in NSCLC ^[9]B2a. In oligometastatic NSCLC specifically, a systematic review from 2025 confirms that consolidative SBRT improves PFS and OS when integrated with immunotherapy or targeted therapy, yet it emphasizes the need for randomized trials to define optimal sequencing and patient selection ^[4]D5.

Key ongoing randomized trials (e.g., NRG-LU008, SARON) will provide higher-level evidence for SBRT versus systemic therapy alone in oligometastatic NSCLC. Until these mature, the current practice is supported by single-arm and non-randomized comparative data.

Pearl: Emerging phase 2 data combining durvalumab, chemotherapy, and SABR show promise in oligometastatic NSCLC ^[11]C4, while the AUSTRAL trial will test radiosensitization with ceralasertib ^[12]D5; definitive phase 3 results are awaited before practice change.