S2964
Late-Breaking
ESTRO 2026
Locoregional recurrence rates were low and comparable (7.2% vs 5.0%; HR 1.61, 95% CI 0.80–3.23; p=0.19). Contralateral breast cancer incidence was similar between groups (3.8% vs 5.0%; HR 0.79, 95% CI 0.35–1.81; p=0.58). Distant metastases were infrequent (2.7% vs 4.6%; HR 0.60, 95% CI 0.24–1.52; p=0.28), with no meaningful differences between arms. Overall mortality at 15 years was 21.5% after APBI and 19.6% after WBI (HR 1.14, 95% CI 0.78–1.67; p=0.49). Breast cancer–specific mortality remained low (2.3% vs 3.1%; HR 0.77, 95% CI 0.27–2.22; p=0.63). Most oncological events occurred within the first decade, with a minority of late events beyond 15 years. Conclusion: At 15 years, the phase III APBI-IMRT Florence trial (NCT02104895) demonstrates durable oncological outcomes with PBI in selected patients with early breast cancer. No differences were observed in locoregional control, distant metastasis, or breast cancer-specific survival. These findings provide mature evidence supporting PBI as a safe de-escalation strategy and reinforce its role as a standard treatment option in appropriately selected patients. References: Livi L, Meattini I, Marrazzo L, et al. Accelerated partial breast irradiation using intensity-modulated radiotherapy versus whole breast irradiation: 5-year survival analysis of a phase 3 randomised controlled trial. Eur J Cancer. 2015 Mar;51(4):451-463. doi: 10.1016/j.ejca.2014.12.013. Epub 2015 Jan 17. PMID: 25605582.Meattini I, Marrazzo L, Saieva C, et al. Accelerated Partial-Breast Irradiation Compared With Whole-Breast Irradiation for Early Breast Cancer: Long- Term Results of the Randomized Phase III APBI-IMRT- Florence Trial. J Clin Oncol. 2020 Dec 10;38(35):4175- 4183. doi: 10.1200/JCO.20.00650. Epub 2020 Aug 24. PMID: 32840419. Keywords: Breast cancer; partial breast irradiation; IMRT. Pelvic radiotherapy in patients with very high-risk localized prostate cancer: results of the PEACE 2 phase III randomized trial Pierre Blanchard 1 , Stéphanie Foulon 2 , Xavier Artignan 3 , Josep Jové Teixido 4 , Marco Gizzi 5 , Philippe Ronchin 6 , Paul Sargos 7 , Thomas Dubergé 8 , Pierre Cornillon 9 , Igor Latorzeff 10 , Enrique Gallardo 11 , Sophie Abadie Lacourtoisie 12 , María Isabel Saez 13 , Mostefa Bennamoun 14 , Ali Hasbini 15 , Florence Joly 16 , Alejo Rodriguez Vida 17 , Florence Tantot 18 , Xavier Maldonado 19 , Karim Fizazi 20 1 Radiation Oncology, Gustave Roussy, Villejuif, France. 2 Biostatistics and epidemiology, Gustave Roussy, Proffered Paper 5520
Proffered Paper 5517
Fifteen-year outcomes of the randomised APBI- IMRT Florence phase III trial of partial versus whole-breast irradiation in early breast cancer Icro Meattini 1,2 , Carlotta Becherini 1 , Calogero Saieva 3 , Luca Visani 1 , Marianna Valzano 1 , Andrea Rampini 1 , Viola Salvestrini 1 , Chiara Mattioli 1 , Gaia Troiani 1,2 , Giulia Cesari 1,2 , Sara Pedretti 4 , Beatrice Detti 5 , Silvia Scoccianti 6 , Vanessa Di Cataldo 1 , Isacco Desideri 1,2 , Daniela Greto 1 , Mauro Loi 1 , Gabriele Simonatcchi 1 , Orit Kaidar-Person 7 , Liesbeth J. Boersma 8 , Philip M. P. Poortmans 9 , Livia Marrazzo 10,2 , Stefania Pallotta 10,2 , Lorenzo Livi 1,2 1 Radiation Oncology, Florence University Hospital, Florence, Italy. 2 Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy. 3 Epidemiology, ISPRO, Florence, Italy. 4 Radiation Oncology, Brescia University Hospital, Brescia, Italy. 5 Radiation Oncology, Prato Hospital, Prato, Italy. 6 Radiation Oncology, OSMA Hospital, Florence, Italy. 7 Radiation Oncology, Sheba Medical Center, Ramat Gan, Israel. 8 Radiation Oncology, Maastro, Maastricht, Netherlands. 9 Radiation Oncology, Iridium Netwerk, Antwerp, Belgium. 10 Medical Physics, Florence University Hospital, Florence, Italy Purpose/Objective: Accelerated partial breast irradiation (PBI) is a de- escalated radiotherapy strategy for selected patients with early breast cancer. While randomised trials have demonstrated comparable short- and long-term outcomes versus whole-breast irradiation (WBI), very long-term data remain limited. We report 15-year oncological outcomes from a randomised phase III trial (ClinicalTrials.gov NCT02104895) comparing PBI and WBI. Material/Methods: Patients with early-stage breast cancer undergoing breast-conserving surgery were randomised to PBI (30Gy in five fractions) or WBI (50Gy in 25 fractions with a tumour bed boost) within the phase III APBI- IMRT Florence trial. Analyses were conducted in the intention-to-treat population. Cumulative incidence of oncological outcomes was estimated at 5, 10, and 15 years. Hazard ratios (HR) with 95% confidence intervals (CI) were derived from Cox proportional hazards models. Results: At a median follow-up of 15.9 years (mean 16.5), overall event rates remained low. At 15 years, ipsilateral breast tumour recurrence (IBTR) occurred in 7.7% after PBI and 4.2% after WBI (HR 1.90, 95% CI 0.91–3.98; p=0.086). This difference was mainly driven by new ipsilateral primary tumours (5.9% vs 2.7%) rather than true local relapses (2.1% vs 1.6%).
Made with FlippingBook - Share PDF online