Dzhugashvili, MaiaSerradilla, AnaFernández Ibiza, JaimeGarcía, GracielaMatskov Malinochka, KirillTorres, LisellotSeral, AntonioBegara, JoséGonsalves, DanielaCouñago Lorenzo, FelipeEt. al.2025-09-262025-09-262025Dzhugashvili, M., Serradilla, A., Fernández-Ibiza, J., García, G., Malinochka, K. M., Torres, L., Seral, A., Begara, J., Gonsalves, D., Troca, J. J. D. L. C., Poortmans, P., Couñago, F., & López, E. (2025). Ultrahypofractionation and simultaneous integrated boost in breast cancer: Early side effects analysis. International Journal of Radiation Oncology*Biology*Physics, 122(2), 241-248. https://doi.org/10.1016/j.ijrobp.2025.02.0030360-30161879-355Xhttps://hdl.handle.net/11268/16222The FAST-Forward study paved the way for ultrahypofractionation (UHF) in breast cancer. We prospectively registered and analyzed our case series receiving UHF + simultaneous integrated boost (SIB) to further reduce the treatment to a total of 5 days. The study aimed to present the 6-month early side effects results of the first patients treated with this scheme in 16 radiation oncology centers in Spain. A total of 242 breast cancer patients received adjuvant radiation therapy between April and December 2020. The median age was 61 years (interquartile range, 53-70). All patients underwent breast-conserving surgery. Chemotherapy (QT) was administered to 27.7%, and endocrine therapy to 85.1%. A SIB of 29 Gy was applied to 60.7% of the patients, while 39.3% did not have a boost indication. Breast radiation therapy (RT) with SIB to the tumor bed and regional node irradiation was done in 5.4 % of patients.engNeoplasias de la MamaNeoplasias Asociadas a TratamientoEstudio clínicojournal article10.1016/j.ijrobp.2025.02.003embargoed accessCáncerSalud de la mujerGoal 3: Ensure healthy lives and promote well-being for all at all ages