1-Week Versus 3-Week Partial Breast Irradiation Using Intensity-Modulated Radiation Therapy (IMRT) Following Breast-Conserving Surgery in Clinically Low-Risk Breast Cancer: a Phase III, Randomized Trial
This non-inferiority, phase 3 clinical trial evaluates the cosmetic non-inferiority of a one-week regimen (26 Gy/5 Fx) versus a three-week regimen (40 Gy/15 Fx) using intensity-modulated radiation therapy (IMRT) for partial breast irradiation (PBI) in low-risk breast cancer patients post-breast-conserving surgery.
• Female patients with an estimated life expectancy greater than 5 years. Meets criteria for either primary invasive breast cancer or pure ductal carcinoma in situ (DCIS).
• For invasive breast cancer: Age 40-75 years; Underwent breast-conserving surgery with sentinel lymph node biopsy or axillary lymph node dissection; pT ≤ 3 cm (unicentric/unifocal or total multifocal size ≤ 3 cm); favorable histology (invasive ductal, mucinous, tubular, or solid papillary carcinoma, DCIS component permitted); ER+ and/or PR+; pN0(i- or i+); M0; surgical margins ≥ 2 mm.
• For pure DCIS: Age 18-75 years; Underwent breast-conserving surgery with or without sentinel lymph node biopsy; low-to-intermediate nuclear grade; tumor size ≤ 2.5 cm; surgical margins ≥ 3 mm.
• Presence of surgical clips or distinct postoperative seroma/tissue changes in the tumor bed allowing precise target delineation.
• ECOG performance status 0 or 1.
• Eligible for systemic therapy, without prior neoadjuvant systemic therapy.
• Able to tolerate radiotherapy procedures and position immobilization.
• No contraindications to radiotherapy.
• Written informed consent provided.