Background
Randomized, non-inferiority, open-label phase 3 (single national cancer centre, China). N=820 randomized (810 analyzed), 94% stage III. High-risk breast cancer after modified radical mastectomy + axillary dissection; chest wall + supraclavicular RT. Prespecified 10-year analysis (no further non-inferiority testing).
Results
Interventions and follow up: Arm A: Hypofractionated PMRT 43.5 Gy/15 fx over 3 wk
Arm B: Conventional PMRT 50 Gy/25 fx over 5 wk
Primary endpoint: 5-yr cumulative incidence of locoregional recurrence (5% non-inferiority margin)
mFollow up: 11.5 yr (IQR 9.6-13.8)
Results: 10-yr locoregional recurrence: 12.0% (95% CI 8.8-15.2) vs 10.3% (95% CI 7.3-13.3), HR 1.19 (95% CI 0.79-1.82); no confirmatory non-inferiority testing
Arm B: Conventional PMRT 50 Gy/25 fx over 5 wk
Primary endpoint: 5-yr cumulative incidence of locoregional recurrence (5% non-inferiority margin)
mFollow up: 11.5 yr (IQR 9.6-13.8)
Results: 10-yr locoregional recurrence: 12.0% (95% CI 8.8-15.2) vs 10.3% (95% CI 7.3-13.3), HR 1.19 (95% CI 0.79-1.82); no confirmatory non-inferiority testing
Adverse events
Most common grade 3: ischemic heart disease 1% vs 1%, lymphedema <1% vs 1%, shoulder dysfunction <1% vs <1%, skin AE 0 vs <1%
Grade 4-5: none
Other: no brachial plexopathy, SAEs or treatment-related deaths
Grade 4-5: none
Other: no brachial plexopathy, SAEs or treatment-related deaths
Conclusions
Hypofractionated PMRT gave durable 10-year locoregional control with no excess severe late toxicity vs conventional fractionation, supporting a 3-week schedule after mastectomy with regional nodal RT.
Key Limitations
Single-centre, open-label, Chinese population; 10-year analysis had no confirmatory non-inferiority testing, point estimate numerically favors conventional (HR 1.19, CI wide). Modified ITT excluded 10 pts. No breast reconstruction detail in abstract; race/ethnicity not collected. Late cardiac events may need longer follow-up.
Clinical Context
Long-term follow-up of the 5-year non-inferiority result. Complements other hypofractionated PMRT/RNI trials (e.g., FAST-Forward-type schedules, HypoG-01 for early stage in this database). Supports 15-fraction PMRT as a time-efficient alternative; fractionation choice still individualized with reconstruction and nodal-volume considerations.
