In a phase III trial (NSABP B-51–RTOG 1304) reported in The New England Journal of Medicine, Mamounas et al examined regional nodal irradiation for activity in preventing invasive breast cancer recurrence or death from breast cancer in patients who had negative axillary nodes after neoadjuvant chemotherapy.
Study Details
The international trial was activated in August 2013 and closed to enrollment in December 2020. A total of 1,556 patients with ypN0 status after neoadjuvant chemotherapy were randomly assigned to receive regional nodal irradiation (n = 772) or no regional nodal irradiation (n = 784). The primary endpoint was the interval of freedom from invasive breast cancer recurrence or death from breast cancer.
Key Findings
After a median follow-up of 59.5 months, primary endpoint events had occurred in 50 patients in the irradiation group and 59 in the no-irradiation group. The irradiation group did not exhibit a significant increase in invasive breast cancer recurrence-free interval (hazard ratio [HR] = 0.88, 95% confidence interval [CI] = 0.60–1.28, P = .51). Estimates of survival free from primary endpoint events at 5 years were 92.7% in the irradiation group and 91.8% in the no-irradiation group.
Regional nodal irradiation was not associated with improved locoregional recurrence-free interval (5-year estimate = 98.9% vs 98.4%, HR = 0.57, 95% CI = 0.21–1.54), distant recurrence–free interval (5-year estimate = 93.4% vs 93.4%, HR = 1.00, 95% CI = 0.67–1.51), disease-free survival (5-year estimate = 88.3% vs 88.5%, HR = 1.06, 95% CI = 0.79–1.44), or overall survival (5-year estimate = 93.6% vs 94.0%, HR = 1.12, 95% CI = 0.75–1.68).
No unexpected adverse events were observed, and no treatment-related deaths were reported. Grade 4 adverse events occurred in 0.5% of patients in the irradiation group and 0.1% of those in the no-irradiation group.
The investigators concluded: “The addition of adjuvant regional nodal irradiation did not decrease the risk of invasive breast cancer recurrence or death from breast cancer in patients who had negative axillary nodes after neoadjuvant chemotherapy.”
Eleftherios P. Mamounas, MD, of AdventHealth Cancer Institute, Orlando, Florida, is the corresponding author of The New England Journal of Medicine article.
Disclosure: The study was funded by the National Institutes of Health. For full disclosures of all study authors, visit The New England Journal of Medicine.
