Radiotherapy Study Comparing 5-Fraction Ultrahypofractionated Whole Breast Treatment with Boost to Standard 15-Fraction Treatment for Women With Unfavorable Breast Cancer

What this Trial Is About

This research aims to compare two radiotherapy approaches for women with breast cancer who are either under 40 years old or have unfavorable tumor types such as lobular carcinoma, certain aggressive subtypes, or triple negative breast cancer. The study focuses on patients with clinical stage T1-T3 and lymph node involvement Nx-N3 after breast-conserving surgery, evaluating whether a shorter, more intense treatment schedule is not worse than the current standard treatment. The trial is prospective, randomized, and designed to assess non-inferiority between these treatments. Participants will receive one of two radiation therapy regimens. One group experimental arm will have whole breast irradiation totaling 26 Gy delivered in 5 fractions, with a simultaneous integrated boost SIB to the tumor bed totaling 30 Gy. The other group standard arm will receive whole breast irradiation totaling 40.05 Gy in 15 fractions, with SIB to 48 Gy. Intensity modulated radiotherapy IMRT plans will be used to optimize coverage and protect organs at risk. Both treatments are given after surgery and may include lymph node areas. During the study, participants will be monitored for local relapse-free survival over 5 years, along with various toxicity assessments at 1 month, 3 months, and up to 5 years. Other outcomes include local control, breast tumor recurrence, regional relapse-free survival, distant metastasis-free survival, disease-free survival, breast cancer-specific survival, overall survival, and cosmetic results. Additional evaluations will assess treatment-emergent adverse events, organ movement, radiomics, and predictive factors for toxicity and disease progression. The study will run through June 2035.

5 fr Ultrahypofractionated WBI and SIB for Breast Cancer With Unfavorable Characteristics