Ultra-Hypofractionated Whole-Breast Irradiation With or Without Simultaneous Integrated Boost Using Helical Tomotherapy for Early-Stage Breast Cancer: A Real-World Dosimetric and Clinical Outcome Study

Background: Ultra-hypofractionated whole-breast irradiation (WBI) delivering 26 Gy in five fractions has been established as a standard of care following the FAST-Forward trial. However, real-world data addressing advanced delivery techniques and the feasibility of incorporating a simultaneous integrated boost (SIB) remain limited. Methods: We retrospectively analyzed 40 patients with early-stage breast cancer (pT1–2N0M0) treated with breast-conserving surgery, followed by ultra-hypofractionated WBI using helical tomotherapy. Patients received either WBI alone (26 Gy in five fractions) or WBI with an SIB to the tumor bed (29–30 Gy in five fractions). Dosimetric parameters for planning target volumes (PTVs) and organs at risk (OARs) were evaluated. Acute skin toxicity was assessed using CTCAE version 5.0. Results: The median patient age was 55.7 years. The mean PTV V95% was 97.8%, with excellent hotspot control (PTV V105% < 5% and V107% < 2%). For left-sided tumors, the mean heart dose was 1.67 Gy, and the ipsilateral lung V8Gy remained below 15% in all patients. Acute radiation dermatitis was limited to Grade 0–1 in all cases. At a median follow-up of 14.8 months, both local control and overall survival were 100%. Conclusions: Ultra-hypofractionated WBI delivered using helical tomotherapy, with or without SIB, demonstrates robust dosimetric quality, minimal acute toxicity, and favorable early clinical outcomes in routine clinical practice.