Single-fraction APBI for Early-stage Breast Cancer With Favorable Histological Subtypes (Breast-1F)

Inclusion Criteria

• •1. Histological diagnosis of breast cancer
• •2. Patients aged ≥40 years
• •3. Signed informed consent
• •4. Stage pTis-T2, up to 3 cm in the greatest diameter
• •5. Luminal A and Luminal B HER2-negative histological subtypes
• •6. Negative surgical margins (≥ 0.2 cm)
• •7. Negative lymph nodes at sentinel lymph node biopsy, or alternatively with imaging tests (Positron Emission Tomography (PET)/Computed Tomography (CT) and/or axillary ultrasound, and/or breast Magnetic Resonance Imaging (MRI) with and without contrast), or, in rare cases, where still performed, with axillary dissection
• •8. Clinical M0 (PET/CT and/or bone scintigraphy and/or abdomen-pelvis CT with and without contrast in suspected patients), within the previous 3 months.
• •9. Performance Status (PS) Eastern Cooperative Oncology Group (ECOG) ≤2
• •10. No prior thoracic radiotherapy
• •11. Fertile women using contraception methods initiated during oncological treatment.