Radiation Oncology Guidelines for Breast Cancer

Introduction to Radiation Therapy

• The National Comprehensive Cancer Network recommends hypofractionated whole breast irradiation at 40-42.5 Gy in 15-16 fractions as the preferred standard after breast-conserving surgery for early-stage breast cancer, with regional nodal irradiation strongly recommended for patients with 1-3 positive nodes and mandatory for ≥4 positive nodes 1, 2, 3

Stage I-II (Early Invasive Disease)

• After breast-conserving surgery, the American College of Radiology recommends whole breast irradiation with a preferred regimen of 40-42.5 Gy in 15-16 fractions (hypofractionation) for patients with early-stage breast cancer 2, 3
• The National Comprehensive Cancer Network strongly recommends tumor bed boost for patients with high-risk features, such as age <50 years, positive axillary nodes, lymphovascular invasion, high-grade disease, or close margins, with a dose of 10-16 Gy in 4-8 fractions 1, 3
• For patients with 1-3 positive nodes, the American Society for Radiation Oncology strongly considers radiation to infraclavicular region, supraclavicular area, internal mammary nodes, and any part of axillary bed at risk, with the same dosing as for ≥4 positive nodes 1, 2, 5

Stage IIIA (T3N1M0)

• After breast-conserving surgery, the National Comprehensive Cancer Network recommends whole breast irradiation with boost and strongly considers regional nodal irradiation to all nodal stations for patients with Stage IIIA breast cancer 1

Technical Specifications

• The American Association of Physicists in Medicine recommends mean heart dose <2.5 Gy and mean left ventricle dose <3 Gy to minimize cardiac exposure during radiation therapy 3
• The American Society for Radiation Oncology recommends CT-based treatment planning to identify and minimize heart and lung exposure during radiation therapy 3

Common Pitfalls

• The National Comprehensive Cancer Network advises against undertreatment of regional nodes in patients with 1-3 positive nodes, as the MA.20 and EORTC 22922/10925 trials demonstrated significant reductions in locoregional and distant recurrence with regional nodal irradiation 4
• The American College of Radiology recommends against basing radiation decisions on post-neoadjuvant pathology alone and considering pre-treatment stage for patients with breast cancer 4, 6