Ultra-Hypofractionated Radiotherapy Plus Boost for T1-2 Breast Cancer Patients: Early Results of a Prospective Study Based on the Fast-Forward Scheme.

Objective: Hypofractionated radiotherapy (RT) is the standard adjuvant treatment for breast cancer patients after surgery. The recent results of the FAST-FORWARD trial on ultra-hypofractionated RT, delivered over one week, support a viable alternative regimen for early-stage breast cancer. Whether the addition of a tumor bed boost could further improve patient outcomes is still under investigation. Materials and Methods: We report the results of a single-center prospective study involving 26 early-stage (T1, 2N0) breast cancer patients treated with whole-breast RT consisting of five daily fractions of 5.2 Gy (FAST-FORWARD regimen) followed by a tumor-bed boost of three daily fractions of 3 Gy. Results: Grade 1 early breast toxicity (skin changes and altered breast consistency) was documented in 20% of patients within the first 3 months after treatment completion. No events of acute pneumonitis were reported. Whole-breast and tumor-bed boost volumes did not affect the occurrence of breast toxicity. Minimal radiation-induced lung injury (grade 1) was noted in 95.8% of patients, while one patient (4.2%) developed grade 2 lung toxicity, which was later downgraded to grade 1 at the 12-month post-RT time point. With a median follow-up of 72 months, none of the patients presented with locoregional recurrence or distant metastases. Conclusion: The present study highlights the safety of a hypofractionated RT boost to the tumor bed after ultra-hypofractionated whole-breast RT. No clear evidence exists to date regarding the superiority of delivering a tumor bed boost after ultra-hypofractionated RT or the specific patient subgroups to which a boost should be prescribed.