KEY POINTS
- This single-centre retrospective study included 90 patients with stage IV non-small cell lung cancer treated during first-line systemic therapy.
- Consolidative SABR was delivered before progression in 64 patients, while 26 patients received salvage SABR for primary-site oligoprogression.
- The cohort was highly selected: 96.7% had an Eastern Cooperative Oncology Group performance status of 0–1, 66.7% had EGFR mutations or ALK fusions and 93.3% had adenocarcinoma.
- The most frequently used schedule was 10 Gy × 5 fractions, with a median biologically effective dose of 100 Gy. Seven ultracentral tumours received lower-dose hypofractionation.
- SABR was delivered a median of 5.6 months after systemic therapy initiation in the consolidative group and 10.3 months in the salvage group (p = 0.001).
- Median local progression-free survival was 42.7 versus 52.6 months (p = 0.848), distant metastasis-free survival was 29.4 versus 19.1 months (p = 0.806) and overall survival was 59.6 versus 53.1 months (p = 0.775).
- Grade 2 radiation pneumonitis occurred in 10.9% versus 15.4% of patients, with no grade 3 or higher toxicity. SABR timing was not independently associated with any survival endpoint.
CLINICAL TAKEAWAY
Deferring primary-tumour SABR until oligoprogression did not appear to compromise outcomes in this selected cohort receiving effective systemic therapy. The study does not prove equivalence because treatment was non-randomized, the salvage group was small and two-thirds of patients had targetable oncogenic drivers.