Locoregional Rt After Bct
  • MA.20
  • Evaluated the addition of regional nodal irradiation (RNI) to whole breast irradiation (WBI) following breast conserving surgery (BCS)
  • Patients:
    • High risk node-negative
      • 10% of patients
    • Node-positive
      • 1-3 positive nodes, 85%
      • > 4 positive nodes, 5%
    • BCS
    • Adjuvant chemotherapy and/or endocrine therapy
      • Adjuvant chemotherapy, 91%
      • Adjuvant endocrine therapy, 71%
  • Stratification:
    • Positive nodes, axillary nodes removed, chemo- and endocrine therapy
  • Randomized to:
    • WBI (50Gy in 25 fractions +/- boost irradiation)
    • WBI plus RNI (45Gy in 25 fractions)
      • Internal mammary
      • Supraclavicular
      • High axillary lymph nodes
  • Primary outcome —> OS
    • 5 years
    • WBI+RNI in comparison to WBI alone was associated with an improvement in isolated locoregional disease free survival (DFS; HR=.59, p=.02, 5 year risk: 96.8% and 94.5% respectively), distant DFS (HR=.64, p=.002, 5 year risk: 92.4% and 87.0% respectively), DFS (HR=.68, p=.003, 5 year risk: 89.7% and 84.0% respectively) and OS (HR=.76, p=.07, 5 year risk: 92.3% and 90.7% respectively). WBI+RNI in comparison to WBI was associated with an increase in grade 2 or greater pneumonitis (1.3% and 0.2% respectively, p=.01), and lymphedema (7.3% and 4.1% respectively, p=.004). Conclusions: The majority of women with node positive breast cancer are now managed by BCS followed by WBI and adjuvant systemic therapy. Results from MA.20 demonstrate that additional RNI reduces the risk of locoregional and distant recurrence, and improves DFS with a trend in improved OS.