S313
Clinical - Breast
ESTRO 2026
SABR-COMET Phase II Randomized Trial. J Clin Oncol 2020;38:2830-8 Keywords: Breast cancer; Systemic therapy; Radiation therapy
significantly improve local disease control and OS. We conducted a retrospective multicentre data collection to assess the safety of the concomitant administration of SG and RT in TNBC patients. Material/Methods: A retrospective analysis was conducted on patients with metastatic TNBC treated at 4 leading European institutions across 3 different countries. Ablative RT was defined based on a biological dose threshold of a minimum of 50Gy EQD2(10) delivered in no more than 12 fractions, as per the European Society for Radiotherapy and Oncology (ESTRO) OligoCare study. The primary objective was to assess the association between RT and adverse events (AEs) greater than grade (G) 2. Results: Data from 68 consecutive patients treated with SG, with or without RT, were retrospectively evaluated. Twenty-eight patients received RT immediately before (within 2 weeks) or during SG without interruptions, amounting to 39 concurrent RT treatments, while 40 patients did not receive RT. The median age at SG initiation was 64 years old (range 36-84), and the median follow-up from SG initiation was 12 months (range 1–50). Most patients received SG as second line of systemic therapy for metastatic disease (N=28, 41.2%). The median total RT dose was 25Gy (range 8– 54), delivered over a median of 8 fractions (range 1– 18). The median EQD2 dose was 28Gy (range 12–83), and the median BED was 34Gy (range 14–100). The bone was the most frequently treated site (40.1%; N=16/39 treatments). Seventeen patients (60.7%) received RT with ablative intent, 11 patients (39.3%) received palliative RT only. The relationship between RT administration and the development of >G2 toxicity was not statistically significant (p=0.096) at chi-square test. In the RT cohort, SG dose was reduced in 5 patients (17.9%) and it was permanently discontinued in 4 cases (14.3%) for toxicity. In the no RT cohort, SG dose was reduced in 9 cases (22.5%); a definitive discontinuation was reported in 3 patients (7.5%). Conclusion: Our preliminary findings are encouraging, suggesting that the combination of SG and concurrent RT does not increase the risk of severe acute toxicity. References: 1. Bardia A. et al. Sacituzumab Govitecan in Metastatic Triple-Negative Breast Cancer. N Engl J Med 2021;384:1529-1541.2. Bardia A. et al. Final Results From the Randomized Phase III ASCENT Clinical Trial in Metastatic Triple-Negative Breast Cancer and Association of Outcomes by Human Epidermal Growth Factor Receptor 2 and Trophoblast Cell Surface Antigen 2 Expression. J Clin Oncol 2024;42,1738- 1744.3. Palma DA et al. Stereotactic Ablative Radiotherapy for the Comprehensive Treatment of Oligometastatic Cancers: Long-Term Results of the
Digital Poster 3915 Intraoperative Radiotherapy with INTRABEAM® in Early-Stage breast Cancer patients: a 10-Year Monocentric experience Anna Vialard 1 , Constance Huck 2 , Imed Taleb 2 , Mathilde Maire 1 , Jerome Caron 2 , Sophie Auriol 1 , Anne De La Rochefordiere 2 , Julie Babin-commeny 1 , Sophie Hezer 1 , Nicolas Dantin 1 , Marion Fournier 1 , Adeline Petit 2 , Nicolas Magne 2 1 department of Surgery, Institut Bergonié, Bordeaux, France. 2 department of Radiotherapy, Institut Bergonié, Bordeaux, France Purpose/Objective: Breast-conserving surgery (BCS) followed by external beam radiation therapy (EBRT) is the current standard for early-stage breast cancer. In the context of therapeutic de-escalation, intraoperative radiation therapy (IORT) has emerged as a promising alternative for patients with low-risk profiles. This study reports a 10-year single-center French experience using Intrabeam® IORT Material/Methods: We retrospectively analyzed 247 patients treated with BCS and IORT between 2012 and 2021 at a single institution. IORT was delivered using Intrabeam® (20 Gy to the tumor bed). Patients were selected based on ASTRO guidelines or inclusion in IORT trials (TARGIT or RE-IORT). Endpoints included patient and tumor characteristics, postoperative and delayed complications, and oncological outcomes. Survival analysis was performed in patients who received IORT alone (n = 187), without further radiotherapy or re-
excision Results:
A total of 247 patients underwent IORT. The median age was 71 years, and most had tumors ≤ 20 mm, grade I or II, and of invasive ductal carcinoma histology. Only 20.6% required additional EBRT based on final pathology. Grade II postoperative complications occurred in 12.9%, primarily seromas. Delayed complications were rare (clinical fat necrosis: 1.4%, radiological fat necrosis: 21%).Among the 187 patients who received IORT alone, the 5-year invasive disease-free survival (i-DFS) was 85.5% (95% CI [77.9– 90.6]), and overall survival (OS) was 91.8% (95% CI [84.5–95.8]). The 5-year ipsilateral breast tumor recurrence (IBTR) rate was 1.2%. Conclusion: IORT with Intrabeam® provides excellent local control
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