Background
Phase III, open-label RCT. 4004 patients with stage I–III breast cancer after BCS or mastectomy at risk for internal mammary chain (IMC) and medial supraclavicular nodal involvement: node-positive disease, or medial/central tumor location in node-negative patients. Tested whether adding internal mammary/medial supraclavicular (IM-MS) nodal irradiation to locoregional RT improves survival.
Interventions and follow up
Arm A: Whole-breast or chest-wall RT + IM-MS nodal irradiation (internal mammary + medial supraclavicular fossa)
Arm B: Whole-breast or chest-wall RT alone (no nodal RT)
Primary endpoint: Overall survival (OS)
mFollow up: 10.9 years
Arm B: Whole-breast or chest-wall RT alone (no nodal RT)
Primary endpoint: Overall survival (OS)
mFollow up: 10.9 years
Results
OS (10-yr): 82.3% vs 80.7%, HR 0.87, 95% CI 0.76–1.00, P=.06 — borderline
DFS: HR 0.89, 95% CI 0.80–1.00, P=.04
Distant metastasis-free interval (DMFI): HR 0.86, 95% CI 0.76–0.98, P=.02
Breast cancer mortality: HR 0.82, 95% CI 0.70–0.97, P=.02
DFS: HR 0.89, 95% CI 0.80–1.00, P=.04
Distant metastasis-free interval (DMFI): HR 0.86, 95% CI 0.76–0.98, P=.02
Breast cancer mortality: HR 0.82, 95% CI 0.70–0.97, P=.02
Adverse events
Pulmonary: Grade ≥2 lung fibrosis/pneumonitis 4.4% vs 1.3% (nodal RT vs no nodal RT).
Cardiac: Cardiovascular events similar overall; numerically more ischemic heart disease with nodal RT, not statistically significant at primary analysis.
Other: Contralateral breast cancer and lymphedema rates similar between arms.
Cardiac: Cardiovascular events similar overall; numerically more ischemic heart disease with nodal RT, not statistically significant at primary analysis.
Other: Contralateral breast cancer and lymphedema rates similar between arms.
Conclusions
IM-MS nodal irradiation was associated with significantly better disease-free survival, distant metastasis-free interval, and breast cancer mortality at 10.9 years. The OS difference was borderline (P=.06) but clinically meaningful (~1.6% absolute improvement). EORTC 22922 provided primary evidence for regional nodal irradiation in node-positive early BC.
Key Limitations
OS P-value was borderline non-significant (P=.06) despite robust disease-free and breast cancer mortality benefits. Long-term cardiovascular toxicity from IMC irradiation is a clinically significant concern — left-sided tumors may receive cardiac doses associated with coronary artery disease over decades. Modern cardiac-sparing techniques (deep inspiratory breath hold, proton therapy) were not used in this older trial. RT techniques have evolved substantially since enrollment (1996–2004).
Clinical Context
EORTC 22922, together with MA.20, forms the evidence base for regional nodal irradiation (RNI) in node-positive early breast cancer. ASTRO and ESMO guidelines recommend RNI (including IM and supraclavicular nodes) for most node-positive patients. Cardiac-sparing techniques are essential, particularly for left-sided tumors. Individual patient data meta-analysis estimates a 1–2% absolute 10-year OS benefit. ESMO-MCBS: not applicable (RT trial).
References