S231
Clinical - Breast
ESTRO 2026
References: 1. Schoenfeld JD, Harris JR. Breast [Internet]. 2011;20 Suppl 3:S116-27. 2. Douglas W, Arthur FA. J Clin Oncol. 2005;23:1726–35.3. Smith BD, Arthur DW, Buchholz TA, et al. Int J Radiat Oncol Biol Phys [Internet]. 2009;74(4):987–1001. 4. Whelan TJ, Julian JA, Berrang TS, et al. Lancet [Internet]. 2019;394(10215):2165–72. Keywords: Parcial Breast Irradiation, breast cancer RapidArc Dynamic: towards a new standard for patients with locally advanced breast cancer. Sofiane Allali, Pierre Loap, Youlia Kirova, jeremi vu- bezin radiotherapy, institut curie, paris, France Purpose/Objective: Breast cancer is the most common cancer among women. In the management of localized and locally advanced breast cancer, radiotherapy plays a pivotal Digital Poster 1090 role. Hypofractionated techniques, particularly intensity-modulated radiation therapy (IMRT) with volumetric modulated arc therapy (VMAT), are now the standard of care. This dosimetric study aimed to assess whether a new irradiation approach called RapidArc Dynamic (RAD) (combining VMAT and fixed- field IMRT) offers dosimetric advantages over full VMAT in patients with locally advanced breast cancer. Material/Methods: We retrospectively analyzed treatment plans of 20 consecutive patients treated in our department with breast and lymph node irradiation. Each patient served as her own control, comparing hybrid versus VMAT plans. The prescribed dose was 40.05 Gy to the breast and lymph nodes, with an integrated boost of 48 Gy in 15 fractions, delivered under Deep Inspiration Breath Hold (DIBH). Plans were generated by a dedicated breast oncology physicist. Parameters evaluated included conformity, target coverage, and dose to organs at risk (OAR). Statistical comparisons were performed between the two techniques. For this study, we used the latest RapidArc Dynamic module developed by Varian Systems Results: Among the patients, 50% were treated on the right side, 50% on the left; 70% received axillary irradiation. Target coverage and conformity were equivalent between VMAT and RAD plans. RAD irradiation significantly reduced doses to the heart, contralateral breast, and low-dose lung volumes, independent of laterality. Mean heart dose was reduced by approximately 1 Gy. The most notable reductions were observed for contralateral breast dose (2.8 Gy to 1.5 Gy) and low-dose lung exposure. For cardiac substructures, the left ventricle mean dose decreased
For Disease Free Survival (DFS) and Local Recurrence Free Survival (LRFS) (Fig 3) there were no differences between PBI and control group, with HR for DFS of 0·922 (95% CI 0·399 – 2·130) and HR 0·533 (95% CI 0·107-2·645).
Conclusion: Partial Breast Irradiation is a secure and adequate option for carefully selected patients with low-risk early breast cancer treated with breast conservative surgery, offering similar outcomes that conventional schedules, shortening the treatment; the use of this kind of treatments could impact to high volume centers with long waiting times and health-care cost saving.
Made with FlippingBook - Share PDF online