ESTRO 2022 - Abstract Book

S1045

Abstract book

ESTRO 2022

the median follow-up of 14.8 years (range of 0.1–27), 37 (4.2%), 45 (5.1%), 5 (0.5%), and 18 (2%) patients experienced non- invasive ipsilateral breast tumor recurrence (IBTR), invasive IBTR, regional recurrence and distant relapse, respectively, and 151 (17.1%) patients died. The 15-year LRR were 3.6%, 10.6% and 15% for the mastectomy, BCS+RT and BCS groups, respectively. The corresponding 15-year iRFS rates were 94%, 94% and 77% (p<0.001), respectively (Figure 1).

Compared to mastectomy and BCS+RT groups, BCS group had more invasive IBTR (2.3% and 2.6% versus 10.1%; p<0.001). There were less non-invasive IBTR in the mastectomy group compared to BCS+RT or BCS groups (0.6% versus 7.5% and 4.9%; p>0.001). Compared to positive resection margins (R1), negative resection margins (either <2 mm or ≥ 2 mm), were associated with improved iRFS (Hazard Ratio (HR) 0.75, 95% confidence intervals (CI) 0.61–0.92; p=0.010). Among patients treated with BCS (n=572), not-receiving postoperative RT (HR 4.06, 95 % CI 1.83–9.04; p<0.001) and a higher patient prognostic score ( ≥ 2 points; HR 2.33, 95% CI 1.15–4.72; p=0.018) were both associated with worse iRFS (Figure 2).

Conclusion Our study demonstrated equivalent invasive IBTR and iFRS rates in patients treated with either mastectomy or BCS+RT. Not- receiving RT following BCS was associated with worse outcomes regardless of patient prognostic score.

Poster (digital): Lung

PO-1239 Heart substructures delineation in central lung SBRT and cardiac toxicity

M. Rodriguez Pla 1 , D. Dualde Beltrán 1 , A. Aliaga Chueca 1 , M. Soler Rodríguez 1 , R. García Gómez 1 , E. Jordá Sorolla 1 , M. Maroñas Martín 1 , E. Ferrer Albiach 1

1 Hospital Clinico Universitario de Valencia, Radiation Oncology, Valencia, Spain

Purpose or Objective The use of stereotactic body radiotherapy (SBRT) remains a challenge in the treatment of central lung lesions. We report the dose to heart substructures and its related toxicity.

Materials and Methods