ESTRO 2023 - Abstract Book

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ESTRO 2023

arms. Nevertheless, significantly worse scores on the pain and breast symptom scale emerged at the end of radiation in the WBI arm (p<0.001). During the follow-up visits, these differences between arms were gradually disappearing. The future perspective on the functional scale had a better outcome in APBI arm mat M3 and M6. Moreover, patients in APBI arm reported a more favorable global health status at M6. Conclusion Early BC patients treated with APBI showed non-inferior short-term and late follow-up HRQoL outcomes compared with WBI. Promising pain and breast symptoms results suggest that APBI should be strongly considered in the treatment choice for selected low-risk patients. Supported by grant NV19-03-00354 of the Czech Ministry of Health.

PO-1277 External beam APBI in early breast cancer - final results of prospective single institution study.

P. Burkon 1,2 , I. Selingerova 3,4 , M. Slavik 1,2 , T. Kazda 1,2 , M. Vrzal 1 , P. Slampa 1,2

1 Masaryk Memorial Cancer Institute, Department of Radiation Oncology, Brno, Czech Republic; 2 Faculty of Medicine, Masaryk University, Department of Radiation Oncology, Brno, Czech Republic; 3 Masaryk Memorial Cancer Institute, Research Centre for Applied Molecular Oncology, Brno, Czech Republic; 4 Faculty of Medicine, Masaryk University, Department of Pharmacology, Brno, Czech Republic Purpose or Objective The adjuvant radiotherapy (RT) of the early-stage breast cancer patients is widely established method to cure microscopic residual disease. Nowadays accelerated partial breast irradiation (APBI) is recommended for highly selected patients. This prospective randomized study compares the targeted APBI with commonly used accelerated whole-breast irradiation (WBI) in terms of feasibility, safety, tolerance, and cosmetic effects. Definitive results are presented. Materials and Methods Early-stage breast cancer patients after partial mastectomy were screened for eligibility. The inclusion criteria were age ˃ 50 years, non-lobular histology, ≤ 2 cm, margins ≥ 2 mm, L0, ER-positive, HER-2 negative. All patients were equally randomized into two arms according to the radiotherapeutic regiment – external APBI (5 × 6Gy) and accelerated whole breast irradiation with the boost (15 × 2,67Gy + 5 × 2Gy). The follow-up visits were planned at the end of RT, 1 month after RT, and then every 3 months. Cosmetics results and toxicity were evaluated using questionnaires, CTCAE criteria, and photodocumentation of the irradiated chest. Results The final analysis contains data of 84 randomized patients with he median age 64 years. The tumors were grade 1 in 59 % of patients, the median of 10 mm and 76 % were classified as invasive ductal carcinoma. Toxicity evaluation showed statistically significantly fewer acute adverse events (at the end and 1 month after RT) in the APBI arm in terms of skin erythema, desquamation, skin tenderness, dryness, edema, pigmentation, breast pain and fatigue. Late toxicity (3, 6, 9, and 12 months after RT) was worse in the WBI arm. However, the difference between arms was blurred over time. At the 12 months after RT, a difference in pigmentation was mainly observed. The cosmetic effect (independently evaluated by physician, nurse, and patient) was more favorable in the APBI group. Conclusion The external APBI technique demostrated better feasibilty and less toxicity than standard regiment in adjuvant setting in the treatment of early-stage breast cancer patients. The study incerases its evidence for using in in clinical practice. Supported by grant NV19-03-00354 of the Czech Ministry of Health. M.A. Zerella 1 , S. Dicuonzo 1 , M. Zaffaroni 1 , M.A. Gerardi 1 , D.P. Rojas 1 , A. Morra 1 , D. Nicolò 2 , R. Cambria 3 , R. Luraschi 3 , F. Cattani 3 , R. Orecchia 4 , M.C. Leonardi 1 , B.A. Jereczek-Fossa 1 1 Istituto Europeo di Oncologia, Radiotherapy, Milan, Italy; 2 Università degli Studi di Milano, Oncoematology, Milan, Italy; 3 Istituto Europeo di Oncologia, Medical Physics, Milan, Italy; 4 Istituto Europeo di Oncologia, Scientific Direction, Milan, Italy Purpose or Objective The increasing use of immediate breast reconstruction (IBR) after mastectomy and its interaction with post-mastectomy radiotherapy (PMRT) has become a subject of great interest. In fact, besides the potential impact of RT on the cosmetic results, the reconstructed breast may affect the ideal target coverage and the optimal OARs sparing. Preliminary experience with implant-sparing RT using the HALFMOON (Helical ALtered Fractionation for iMplant partial OmissiON) technique and target contouring according to ESTRO-ACROP recommendation has been reported Materials and Methods Breast cancer patients treated with mastectomy, either total or nipple sparing, and immediately reconstructed with implants (either tissue expander -TE or permanent implant-PI) and receiving Halfmoon RT by using TomoTherapy® Hi-Art System (Tomotherapy Inc., Madison, WI) in helical modality (TomoHelical) at the IEO between February 2020 and January 2021 were considered for the analysis. All the implants were placed beneath the pectoral muscle. As for our clinical practice, TE was fully inflated before RT. Contouring was based on ESTRO/ACROP guidelines for PMRT after implant-based IBR. The chest wall CTV is composed of ventral part (between the skin and the implant); in case of adverse tumor factors, the partial dorsal part (between the implant and the rib wall) is added to ventral CTV. Data about capsular contracture of the breast implant were collected according to the Baker classification PO-1278 Halfmoon radiotherapy: a real-world experience in a single institution