Background
Phase III LUSTRE trial, N=203 with medically inoperable stage I NSCLC, comparing stereotactic body radiotherapy (SBRT) vs hypofractionated conventional radiotherapy to test whether SBRT improves local control.
Interventions and follow up
Arm A: SBRT – 54 Gy in 3 fractions (peripheral) or 60 Gy in 8 fractions (central)
Arm B: Hypofractionated conventional RT – 60 Gy in 15 fractions
Primary endpoint: 3-yr local control
mFollow up: 40 mo
Arm B: Hypofractionated conventional RT – 60 Gy in 15 fractions
Primary endpoint: 3-yr local control
mFollow up: 40 mo
Results
3-yr local control: 93% SBRT vs 91% conventional, not significant
3-yr OS: 56% vs 55%, not significant
3-yr OS: 56% vs 55%, not significant
Adverse events
Overall toxicity: Similar between arms; no grade 5 toxicity
Pulmonary: Grade ≥3 pulmonary events ~10% in both arms
Pulmonary: Grade ≥3 pulmonary events ~10% in both arms
Conclusions
SBRT did not significantly improve local control or survival over hypofractionated RT for medically inoperable stage I NSCLC; both achieved ~90+% 3-yr local control. SBRT remains preferred largely for its shorter, more convenient schedule rather than superior efficacy.
Key Limitations
Modest sample (N=203); fewer events than anticipated limited power; central tumor fractionation differed; non-inferiority not formally established.
Clinical Context
SBRT is standard of care for medically inoperable early-stage NSCLC per ASCO/ASTRO guidance; LUSTRE supports its continued use chiefly on convenience grounds where conventional RT remains an acceptable alternative.