For years, radiation oncologists and surgeons have offered patients with newly spread but apparently limited breast cancer an aggressive proposition: let us ablate every visible metastasis and we may change your disease’s natural history. NRG-BR002, the first breast cancer-specific randomized trial of that proposition, has delivered its answer — and it is no.

The trial (NCT02364557), sponsored by NRG Oncology and funded by the National Cancer Institute, enrolled 129 women across more than 160 U.S. and international sites. Patients had newly oligometastatic breast cancer — up to four extracranial metastatic lesions, each no larger than 5 cm, with a controlled primary — and were on first-line standard systemic therapy for no more than 12 months at registration. They were randomized 1:1 to standard-of-care (SOC) systemic therapy alone or SOC plus stereotactic body radiotherapy (SBRT) and/or surgical resection of all known metastases.

The Phase II primary endpoint was a progression-free survival signal sufficient to justify proceeding to a fully powered Phase III overall survival analysis. That signal did not materialize. Median PFS was 23 months in the SOC-alone arm versus 19.5 months in the ablation arm. Two-year PFS rates were nearly identical — 45.7% versus 46.8% — and three-year rates were 32.8% versus 38.1%, differences that were neither statistically nor clinically meaningful. Median overall survival was not reached in either arm; 36-month OS was 71.8% in the SOC arm and 68.9% in the ablation arm (log-rank p = 0.54).

One secondary finding was biologically instructive: ablation did suppress in-field recurrence — only 6.7% of ablation-arm patients developed new metastases inside the treated area, versus 29.2% in the SOC arm. Yet new metastases outside the treated field emerged at equal rates in both groups (approximately 40%). The implication is stark: eradicating the visible disease does not address the systemic seeding already underway.

Safety was not the limiting factor. There were no grade 5 treatment-related events. Grade 3 adverse events occurred in 9.7% of SOC-alone patients and 5.3% of the ablation group — low rates that confirm modern SBRT is deliverable safely in this setting.

The consequence is decisive: NRG-BR002 will not advance to the Phase III component. The Phase III arm was designed to detect an OS benefit; absent a Phase II PFS signal, accrual to that larger, longer study was not warranted.

Trial Card — NCT02364557

  • Phase: II/III (Phase III did not proceed)
  • Sponsor: NRG Oncology | Collaborator: NCI
  • Enrollment: 129 | Final completion: September 4, 2025
  • Registry: NCT02364557

The results join a pattern emerging across tumor types: local ablation controls the treated site but does not rewrite the metastatic program. Whether better patient selection — guided by ctDNA kinetics or receptor subtype — could identify a subset who benefit remains an active research question. For now, outside a clinical trial, the evidence does not support adding SBRT or surgery to systemic therapy in the first-line oligometastatic breast cancer setting.

Correction, 2026-06-22: An earlier version of this article described NRG-BR002 as “the largest randomized test” of ablative therapy in oligometastatic breast cancer. Primary sources consistently describe it as the first breast cancer-specific randomized trial of this question, not the largest; with 129 patients it is a Phase IIR signal-detection study, not a definitive Phase III. The article’s headline has also been updated to remove the word “Definitive,” which overstated the conclusiveness of a Phase IIR screening trial powered at α=0.15. The core finding — that the Phase II signal criterion was not met and Phase III will not proceed — is unchanged.