Background
1,851 women with invasive tumors <=4 cm (stage I-II, with axillary nodes removed regardless of arm) randomized to evaluate breast conservation versus mastectomy. 20-year follow-up.
Interventions and follow up
Arm A: Total mastectomy
Arm B: Lumpectomy alone
Arm C: Lumpectomy + RT
Primary endpoint: DFS and OS
mFollow up: 20yr
Arm B: Lumpectomy alone
Arm C: Lumpectomy + RT
Primary endpoint: DFS and OS
mFollow up: 20yr
Results
Ipsilateral recurrence (lumpectomy+RT vs lumpectomy alone): 14.3% vs 39.2%
OS: No significant difference among mastectomy vs lumpectomy with or without RT
DFS: No significant difference among the three arms
OS: No significant difference among mastectomy vs lumpectomy with or without RT
DFS: No significant difference among the three arms
Adverse events
Radiation-related: Acute and late skin changes and fibrosis with lumpectomy + RT.
Surgical: Surgical morbidity with mastectomy.
Overall: Breast conservation preserved cosmesis without survival detriment.
Surgical: Surgical morbidity with mastectomy.
Overall: Breast conservation preserved cosmesis without survival detriment.
Conclusions
Lumpectomy plus radiation yields equivalent survival to mastectomy with markedly reduced ipsilateral recurrence versus lumpectomy alone, establishing breast-conserving therapy.
Key Limitations
Predates modern systemic therapy, sentinel node biopsy, and biomarker-guided treatment. Tumors <=4 cm only; results not generalizable to larger tumors. Surgical/RT techniques have since evolved.
Clinical Context
Landmark trial making breast-conserving therapy (lumpectomy + RT) standard of care for early invasive breast cancer, endorsed across ASCO/ESMO surgical guidelines. Complements NSABP B-04 in defining de-escalation of breast surgery.