ESTRO 2023 - Abstract Book

S1037

Digital Posters

ESTRO 2023

Conclusion OART for right-sided WBI is feasible and safe within an acceptable time per fraction, including good patient comfort within the clinical dosimetric requirements. Positioning using marks/tattoos could be omitted in future OART patients. We will expand this study for more complicated breast indications such as locoregional radiotherapy.

PO-1294 Impact of hypofractionated radiotherapy on complication rate after implant-based reconstruction

E. Timoshkina 1 , V. Glebovskaya 1 , O. Trofimova 1 , M. Chernykh 1

1 N.N. Blokhin NMRCO, Radiotherapy Department, Moscow, Russian Federation

Purpose or Objective Hypofractionated radiotherapy in the treatment of breast cancer patients has a significant advantage over conventional fractionation due to the shorter duration of treatment course while maintaining its antitumor efficacy. Usage of hypofractionated regimens may be restricted in patients with immediate breast reconstruction because of possible higher rate of complications. This study aimed to evaluate the incidence of complications in the reconstructed breast after hypofractionated radiotherapy. Materials and Methods The study enrolled 100 patients with breast cancer after immediate implant-based breast reconstruction. 92 patients underwent two-stage immediate reconstruction and were irradiated before expander to implant or flap exchange. Eight patients underwent one-stage direct-to-implant immediate breast reconstruction. An adjuvant course of external beam 3D conformal radiation therapy with a single dose of 2.67 Gy to a total dose of 40.05 Gy to chest wall, reconstructed breast and regional nodes was performed in all involved patients between December 2020 and November 2021. Results We collected the data from eligible 87 patients. During follow-up period of 2 to 15 months, median 6 months, 6 cases of capsular contracture (8%) were identified. We observed 4 cases of grade 1 capsular contracture, 1 case of grade 2 and 1 case of grade 4. In five patients expander was exchanged to permanent implant (n=3), to autologous flap (n=1) and to implant+flap combination (n=1); one patient with grade 4 declined further reconstruction. Additionally, two patients (2,3%) developed infectious complications which led to implant protrusion. Total incidence of protrusion of the implant was 4.6% (n=4), three patients underwent expander exchange to implant+flap combination or to expander, and one declined further reconstruction. Conclusion The total incidence of complications within our study was 15%. Our study demonstrate that hypofractionated radiotherapy in breast cancer patients with immediate implant-based reconstruction led to relatively low incidence of complications and can be further used in clinical practice.

PO-1295 MELT: A novel tool to select the most suitable patients for extreme hypofractionation

J. Gadea 1 , C. Garcia Zanoguera 2 , L. Mateu Castell 3 , I. Ortiz Gonzalez 4 , J. Pardo Masferrer 5

1 Hospital Universitari Son Espases, Radiation Oncology, Palma, Spain; 2 Hospital Universitario Son Espases, Radiation Oncology, Palma, Spain; 3 Hospital universitario Son Espases, Radiation Oncology, Palma, Spain; 4 Hospital Universitario Son Espases, Radiation Oncology , Palma, Spain; 5 Hospital Universitario Son Espases , Radiation Oncology, Palma, Spain Purpose or Objective FAST-Forward trial reported that five-fraction radiotherapy (5fx-RT) schedule with 26Gy in adjuvant setting after breast conserving surgery for early-breast cancer was non-inferior to the standard hypofractionation (SHfx) schedule with 40Gy in