NSABP B-51/RTOG 1304
Trial question
What is the effect of adjuvant regional nodal irradiation in patients with breast cancer who had negative axillary nodes after neoadjuvant chemotherapy?
Study design
Multi-center
Open label
RCT
Population
1556 female patients.
Inclusion criteria: patients with node-positive breast cancer who had negative axillary nodes after neoadjuvant chemotherapy.
Key exclusion criteria: definitive clinical or radiologic evidence of metastatic disease; T4 tumors including inflammatory breast cancer; N2 or N3 disease detected clinically or by imaging; histologically positive axillary nodes post neoadjuvant therapy; microscopic positive margins after definitive surgery; history of non-breast malignancies within 5 years prior to randomization.
Interventions
N=772 regional nodal irradiation (50 Gy in 25 fractions delivered to the retained portion of level I to III axillary nodes along with chest wall after mastectomy or the whole breast after lumpectomy).
N=784 no regional nodal irradiation (no radiation therapy after mastectomy or whole-breast irradiation after lumpectomy).
Primary outcome
Invasive breast cancer recurrence-free interval
93.5%
92.5%
93.5 %
70.1 %
46.8 %
23.4 %
0.0 %
Regional nodal
irradiation
No regional nodal
irradiation
No significant
difference ↔
No significant difference in invasive breast cancer recurrence-free interval (93.5% vs. 92.5%; HR 1.14, 95% CI 0.78 to 1.67).
Secondary outcomes
No significant difference in locoregional recurrence-free interval (99.2% vs. 98.6%; HR 1.75, 95% CI 0.65 to 4.76).
No significant difference in distant recurrence-free interval (94% vs. 93.9%; HR 1, 95% CI 0.66 to 1.49).
No significant difference in disease-free survival (89% vs. 89.4%; HR 0.94, 95% CI 0.69 to 1.27).
Safety outcomes
No significant difference in grade 4 adverse events.
Conclusion
In patients with node-positive breast cancer who had negative axillary nodes after neoadjuvant chemotherapy, regional nodal irradiation was not superior to no regional nodal irradiation with respect to invasive breast cancer recurrence-free interval.
Reference
Eleftherios P Mamounas, Hanna Bandos, Julia R White et al. Omitting Regional Nodal Irradiation after Response to Neoadjuvant Chemotherapy. N Engl J Med. 2025 Jun 5;392(21):2113-2124.
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