- Hypofractionated (HF) postmastectomy radiotherapy (PMRT) vs conventional fractionated (CF)-PMRT for breast cancer is associated with higher rates of late-onset (≥6 months) skin toxicity and subcutaneous tissue toxicity, but lower lung and brachial plexus late toxicity.
- Survival outcomes were no different between groups.
Why this matters
- This cohort study is the largest and longest to date.
- Retrospective cohort comparing long-term outcomes between HF-PMRT (n=980; exposure: 2.65 Gy/fraction to a total of 42.4-53 Gy) and CF-PMRT (n=660; exposure: 2 Gy/fraction to a total of 50-60 Gy).
- Late toxicity was assessed in a subgroup of 480 and 457 patients, respectively.
- Funding: Chiang Mai University.
- Median follow-up was 71.8 months for survival outcomes.
- No differences between groups in 5-year survival outcomes:
- Locoregional recurrence-free survival (LRRFS): 96% for HF-PMRT vs 94% for CF-PMRT; P=.373.
- DFS: 70% vs 72%, respectively; P=.849.
- OS: 73% vs 74%, respectively; P=.463.
- At a median of 106.3 months, HF-PMRT was associated with higher incidence of grade ≥2 late skin toxicity (4% vs 1%) and subcutaneous tissue toxicity (7% vs 2% for CF-PMRT), but lower incidence of lung toxicity (9% vs 16%) and grade 1 brachial plexus toxicity (2% vs 8%).
- No differences between groups in late heart toxicity and lymphedema.
- Retrospective, observational design.