Partial Breast Irradiation Using Non Invasive Approach for Early Stage Breast Cancer

Inclusion criteria

• A confirmed histological diagnosis of invasive breast carcinoma or DCIS
• Age greater or equal to 50 years old
• Life expectancy > 6 months
• Treated by breast conserving surgery with axillary node dissection or sentinel lymph node biopsy
• Pathologic tumor size less than or equal to 2 cm
• Invasive ductal, mucinous, tubular or colloid histology
• Estrogen receptor positive for invasive carcinoma.
• Unifocal/unicentric disease
• Negative surgical margins greater than or equal to 2 mm
• Pathologic lymph node negative
• No evidence of lymphovascular invasion
• ECOG performance status of 0 or 1 (Appendix 1)
• Informed consent signed.

Exclusion criteria

• Known BRCA 1/2 Mutation; (BRCA 1 and 2 testing is not required)
• Autoimmune disorder
• Pregnancy
• Breast implants
• Psychiatric or addictive disorder that would preclude attending follow-up
• Neoadjuvant chemotherapy (adjuvant chemotherapy is permitted)
• Suspicious remaining microcalcification on post-surgery mammogram (unless biopsy proven benign)
• Lobular features on histology (pure or mixed) or sarcoma histology
• Node positive on axillary dissection or in the sentinel lymph node biopsy;
• Extensive in situ carcinoma (EIC)
• Multicentric or multifocal disease
• Paget's disease of the nipple
• Distant metastases
• Lumpectomy cavity not well visualized on AccuBoost imaging
• Lumpectomy cavity with 1cm margin (PTV) not adequately encompassed by any applicator (PTV > 6cm)
• Breast separation with compression > 7cm.
• Overlap of skin between orthogonal treatment axes.