Metastasis-directed therapy (MDT) refers to local treatments—most commonly stereotactic body radiation therapy (SBRT) or metastasectomy—aimed at eradicating individual metastatic lesions in patients with oligometastatic disease, with the intent to improve oncologic outcomes rather than simply palliate symptoms.
It is increasingly used to delay systemic therapy, prolong progression-free survival, and in selected settings may improve overall survival, particularly in oligorecurrent or hormone-sensitive oligometastatic prostate cancer.
Cancer is viewed as existing along a spectrum from purely locoregional to widely systemic disease; oligometastatic states may behave more like a locoregional process and thus be amenable to curative-intent local therapy.
It is the central intervention in the management of oligometastatic disease, typically defined as ≤3–5 metastases) between localized and widely disseminated cancer.
Oligometastatic disease is typically defined as a limited number (often ≤3–5) of metastatic lesions, detectable on modern imaging, with controlled or controllable primary disease.
MDT is generally not curative in polymetastatic biology and often must be repeated as new lesions emerge.
SABR-COMET randomized 99 patients with a controlled primary and 1–5 metastases (1:2) to standard-of-care palliative treatment ± SABR to all lesions.
It met its primary endpoint with a median OS of 41 vs 28 months.
With extended follow-up, benefit was durable: 5-year OS 42.3% vs 17.7% and 8-year OS 27.2% vs 13.6%; 8-year PFS was 21.3% vs 0%.
Notably, 3 of 66 (4.5%) SABR patients had treatment-related deaths, and grade ≥2 toxicity was higher (29% vs 9%).
EXTEND phase 2 is the largest randomized MDT trial to date and confirmed that adding MDT to standard of care improves PFS, with the strongest signals in pancreatic and prostate cancer.
Pooled RCT data consistently show MDT improves PFS and OS.
A 2026 meta-analysis (37 records, 3,500 patients) found upfront MDT improved both PFS and OS with a moderate increase in grade ≥2 adverse events.
A separate meta-analysis found benefit in non-mutated and EGFR-mutated NSCLC and prostate cancer, but not in breast cancer or in oligoprogressive disease.
When SBRT is used without upfront systemic therapy, pooled 1–2 year systemic therapy–free survival is ~70%, highest in renal cell (87%) and prostate (78%) cancers.
Prostate cancer has the most developed framework.
MDT is a preferred in metachronous oligorecurrent mCSPC and oligometastatic mCRPC, and acceptable in synchronous (de novo) oligometastatic mCSPC and oligoprogressive mCRPC.
NSCLC: phase II/III data support local consolidative therapy, particularly with systemic therapy, though the interaction with immunotherapy is unresolved.
Breast cancer: randomized data remain inconclusive.
Renal, pancreatic, and other histologies: emerging benefit signals, but phase III confirmation is pending.
Optimal patient selection remains the key limitation.
Goals of MDT: Achieve durable local control of treated lesions. Delay initiation or escalation of systemic therapy (e.g., androgen-deprivation therapy in prostate cancer). Prolong progression-free survival (PFS) and potentially overall survival (OS) in well-selected patients.
Counting radiographic lesions may be a suboptimal surrogate for micrometastatic burden, and biomarkers (ctDNA, PSMA-PET findings, genomic features) are being investigated to refine selection.
The optimal timing the role and duration of concurrent systemic therapy, and definitive OS benefit await ongoing phase III trials.
Toxicity—including rare treatment-related death—must be weighed, especially for ablative doses near critical organs.
Spectrum theory of metastasis:
Common modalities:
Stereotactic body radiation therapy (SBRT)
Most common MDT modality; highly conformal, hypofractionated radiation to 1–5 metastases.
High local control rates (>90% at 1–2 years in many series); favorable toxicity profile.
Metastasectomy
Selected patients with resectable oligometastases (e.g., lung, liver, bone).
Requires careful patient selection; perioperative risks generally low in experienced centers.
Ablative techniques (RFA, cryoablation)
Alternative for unresectable or radiosensitive lesions in select cases: Less commonly used as primary MDT; data more limited.
Prostate cancer
Two randomized trials and meta-analyses show MDT can delay androgen-deprivation therapy (ADT) by ~2 years in ~50% of men with metachronous hormone-sensitive oligometastatic prostate cancer, with excellent local control and low grade ≥3 toxicity.
A 2026 MD Anderson-led individual patient data analysis demonstrated significant improvements in PFS (+7.6 months), radiographic PFS (+4.9 months), and castration-resistance–free survival (+2.5 months) with MDT + standard of care vs. standard of care alone, without increased severe toxicity.
Prospective trials in non–small cell lung cancer, colorectal cancer, and others suggest MDT can prolong time to progression and delay systemic therapy initiation; OS benefit remains under investigation.
Key factors influencing MDT candidacy include: Number and distribution of metastases (typically ≤3–5, often metachronous).
Disease biology (e.g., hormone-sensitive vs. castration-resistant prostate cancer; indolent vs. aggressive histology).
Imaging modality and sensitivity (PSMA-PET in prostate cancer increases detection of oligometastatic burden).
MDT—particularly SBRT—is generally well tolerated, with grade ≥3 adverse events reported in <1% of patients in meta-analyses (e.g., pathologic fractures after bone SBRT, rare perioperative injuries).
When combining MDT with systemic agents, timing adjustments may be needed to mitigate overlapping toxicities:
BRAF/MEK inhibitors**: Hold ~3 days before and after RT.
VEGF inhibitors (e.g., bevacizumab): Hold ≥4 weeks before and after RT due to wound-healing and bleeding risks.
CDK4/6 inhibitors: Consider holding ~3 days before and after RT.
EGFR/ALK TKIs: Short holds (1–2 days) often recommended in hypofractionated settings.
Immunotherapy: Generally safe concurrently, but caution advised with ultra-hypofractionated regimens; data remain limited.
Many guidelines still recommend MDT primarily within clinical trials or for highly selected patients, citing the need for more level 1 evidence—especially for OS benefit across diverse histologies.
Real-world adoption is increasing, particularly in prostate cancer, where MDT is now frequently discussed in multidisciplinary settings to defer ADT or consolidate response to systemic therapy.