Dosimetric Evaluation of the Fast Forward Protocol with IMRT in Breast Cancer Patients at the Arturo Lopez Perez Foundation Oncology Institute

Introduction: Radiotherapy can treat breast cancer at nearly any stage, with treatment options like a standard regimen of 50 Gy in 25 fractions, a hypofractionated scheme of 40.5 Gy in 15 fractions, and, since 2020, the Fast Forward regimen of 26 Gy in 5 fractions as published in The Lancet. The latter two are recommended for early-stage cancers (pT1-3, pN0-1, M0). Despite the growing popularity of the Fast Forward regimen, it was originally designed for 3D radiotherapy, which limits its applicability due to geometric, volumetric, and dosimetric issues in some patients. In response, the Arturo Lopez Perez Foundation (FALP) implemented Fast Forward using intensity-modulated radiation therapy (IMRT) as an alternative, though dosimetric analysis of this approach is yet to be conducted, along with a comparison of both protocols. Objectives: To dosimetrically evaluate Fast Forward treatment protocols with IMRT and 3D implementations for early-stage breast cancer. Methodology: A quasi-experimental in silico study will be conducted with sample demand data from January 2021 to May 2023. Fast Forward plans using IMRT will be compared to those using 3D protocols, analyzing planning target volume (PTV), high-dose volume, and organ-at-risk doses. Depending on data distribution, T-tests or U-Mann Whitney tests will be applied. Conclusion: Greater efficiency was observed in PTV V24.7 Gy coverage with IMRT, along with reduced high-dose areas within PTV and lower doses to at-risk organs like the ipsilateral lung and skin