ESTRO 2024 - Abstract Book

S556

Clinical - Breast

ESTRO 2024

Kankernetwerk, Department of Radiation Oncology, Wilrijk-Antwerp, Belgium. 8 University of Antwerp, Faculty of Medicine and Health Sciences, Wilrijk-Antwerp, Belgium. 9 McGill University Health Centre, Division of Radiation Oncology, Quebec, Canada. 10 University of Florence, Department of Experimental and Clinical Biomedical Sciences M Serio, Florence, Italy. 11 Azienda Ospedaliero Universitaria Careggi, Radiation Oncology Unit, Oncology Department, Florence, Italy. 12 Sheba Medical Center, Breast Cancer Radiation Therapy Unit, Ramat Gan, Israel. 13 Tel Aviv University, School of Medicine, Tel-Aviv, Israel. 14 Maastricht University, GROW-School for Oncology and Reproductive (Maastro), Maastricht, Netherlands. 15 Winship Cancer Institute, Emory University, Department of Radiation Oncology, Atlanta, USA. 16 University of Calgary, Cumming School of Medicine, Calgary, Canada. 17 Mayo Clinic, Department of Radiation Oncology, Rochester, USA. 18 New York Proton Center and Memorial Sloan Kettering Cancer Center, Department of Radiation Oncology, New York, USA. 19 Hospital Sírio-Libanês, Department of Radiation Oncology, São Paulo, Brazil. 20 Latin America Cooperative Oncology Group, Latin America Cooperative Oncology Group, Porto Alegre, Brazil. 21 Faculdade de Medicina da Universidade de São Paulo, Postgraduate Program. Department of Radiology and Oncology, São Paulo, Brazil

Purpose/Objective:

This study-level meta-analysis assessed toxicities, cosmesis, quality-of-life (QoL), risks of local and locoregional recurrence, and disease-free and overall survival for patients with breast cancer undergoing either breast conserving surgery (BCS) or mastectomy treated with radiation therapy (RT) who participated in randomized controlled trials (RCTs) comparing protracted fractionation (PF), moderate hypofractionation (MHF), and/or ultra hypofractionation (UHF).

Material/Methods:

RCTs)were identified by searching Embase, MEDLINE, and the Cochrane Central Register of Controlled Trials up to 7 February 2023. Pooled effect sizes and 95% confidence intervals (CI) were estimated through a random-effects analysis using RevMan 5.4.

Results:

The risk ratio (RR) for grade ≥2 acute radiation dermatitis for MHF compared to PF was[AR1] 0.51 (95% CI, 0.42 – 0.61; p<0.00001) following BCS, and 0.64 (95% CI, 0.43 – 0.95; p=0.03) following mastectomy. No significant difference was observed in rates of grade ≥2 lymphedema and pneumonitis, lung fibrosis, or other chronic toxicities between MHF and PF. Breast shrinkage was less frequent after MHF, with a RR of 0.91 (95% CI, 0.85 – 0.98; p=0.02). Two trials suggested superior cosmesis with MHF compared to PF, but multiple studies showed no discernible differences. QoL metrics were similar for MHF and PF[AR2] . The RR for grade ≥2 acute radiation dermatitis with UHF compared to MHF was 0.85 (95% CI, 0.47 – 1.55; p=0.60) for BCS and mastectomy patients combined. Oncological outcomes were not significantly different between UHF, MHF, and PF.