Background
Phase III, open-label RCT. 1832 patients with node-positive (76%) or high-risk node-negative breast cancer after BCS with clear margins. Standard WBI vs WBI + regional nodal irradiation (RNI: internal mammary, supraclavicular, high axillary fields). Parallel to EORTC 22922 in testing the value of nodal irradiation extension.
Interventions and follow up
Arm A: WBI + comprehensive RNI (internal mammary chain, medial supraclavicular fossa, high axilla)
Arm B: WBI alone (no nodal RT; level I/II axillary dissection performed in all)
Primary endpoint: Overall survival (OS)
mFollow up: 9.5 years
Arm B: WBI alone (no nodal RT; level I/II axillary dissection performed in all)
Primary endpoint: Overall survival (OS)
mFollow up: 9.5 years
Results
OS (10-yr): 82.8% vs 81.8%, HR 0.91, 95% CI 0.72–1.15 — not significant
DFS: HR 0.76, 95% CI 0.61–0.94, P=.01
Isolated locoregional recurrence: HR 0.59, 95% CI 0.35–0.99, P=.046
Distant DFS: HR 0.76, 95% CI 0.61–0.94, P=.002
DFS: HR 0.76, 95% CI 0.61–0.94, P=.01
Isolated locoregional recurrence: HR 0.59, 95% CI 0.35–0.99, P=.046
Distant DFS: HR 0.76, 95% CI 0.61–0.94, P=.002
Adverse events
Pulmonary: Grade 2 pneumonitis 1.2% vs 0.2% (RNI vs WBI); radiation pneumonitis numerically higher with RNI.
Lymphedema: Grade 2 lymphedema 8.4% vs 4.5% (P=.001).
Cardiac: No significant difference in cardiovascular events at 10 years, though longer follow-up may reveal differences.
Lymphedema: Grade 2 lymphedema 8.4% vs 4.5% (P=.001).
Cardiac: No significant difference in cardiovascular events at 10 years, though longer follow-up may reveal differences.
Conclusions
Adding RNI to WBI significantly improved DFS and distant DFS in node-positive or high-risk node-negative early BC. OS improvement was not statistically significant despite clinically meaningful differences in disease control. MA.20 and EORTC 22922 together support RNI as standard of care in node-positive BC.
Key Limitations
OS non-significant, likely reflecting limited statistical power and extensive post-recurrence salvage therapies. All patients had axillary dissection — applicability to the modern SLNB-alone era (Z0011/SENOMAC) requires considering whether the low axilla receives incidental RT from tangential fields. Lymphedema nearly doubled with RNI (8.4% vs 4.5%) — counseling required. RT techniques used (2000–2007) are dated; modern cardiac-sparing techniques improve the therapeutic ratio.
Clinical Context
MA.20 and EORTC 22922 together provide the highest-level RCT evidence for RNI in node-positive early BC. ASCO and ESMO guidelines recommend RNI for patients with positive nodes after BCS with WBI. The absolute benefit is modest (~1–2% at 10 years) but consistent, with subgroup analyses suggesting greater benefit in ER– and high-risk node-positive patients. Modern cardiac-sparing RT is essential in left-sided tumors. ESMO-MCBS: not applicable (RT trial).
References