Single-Fraction Very Accelerated Partial Breast Irradiation (sfVAPBI)

To investigate clinical outcomes, late side effects, and cosmetic results of a single-fraction very accelerated partial breast irradiation as postoperative local treatment for the treatment of early stage breast cancer.

Accelerated Partial Breast Irradiation (APBI) has demonstrated the non-inferiority compared to external beam radiotherapy (EBRT) in the conserving-treatment of early breast carcinoma by using high-dose-rate (HDR) multicatheter interstitial brachytherapy (MIBT). The standard treatment regimen is 7-8 sessions with two treatments per day, for a total treatment time of 4-5 days. Based on 5-year results of the Groupe Européen de Curiethérapie European SocieTy for Radiotherapy \& Oncology (GEC-ESTRO) Very Accelerated Partial Breast Irradiation (VAPBI) phase I-II trial, in low-risk cases, 3-4 fractions delivered in 2 days reduced the overall treatment time with low rate of side effects and excellent oncological outcome. Retrospective and prospective studies with a single fraction HDR MIBT-based VAPBI suggest that by further increasing the dose delivered in one fraction, the total treatment time can be reduced to a single session safely. A phase II multicenter trial is proposed to confirm this hypothesis.