ESTRO 2021 Abstract Book

S924

ESTRO 2021

Conclusion Our data supports AMAROS with RNI being non-inferior to ANC with regards to OS, CSS, DMFS and LRR. Results support RNI's superiority with regards to QoL. RNI should continue as a treatment option for patients with node positive breast cancer. Disparity between our CSS and OS compared to AMAROS is reflected by analysis of a real world population with likely more comorbidity than a trial population. We analysed patients with higher risk disease than AMAROS (6.8% of our patients had >2LN's positive vs 4% in AMAROS and 4% had >3LN's where AMAROS had none). Our improved CSS is perhaps due to better sentinel nodal staging as the technique has evolved, and more efficacious systemic therapy with the addition of Taxanes/Anti Her-2 therapy. POSNOC is currently researching whether a good prognosis group of patients can be identified where RNI can be omitted. ATNEC is also looking at whether response to NACT could allow omission of RNI. We have performed multivariate analysis that suggests this could be the case in patients with features such as 2LN's or less positive, micromets and ER positivity. PO-1110 Local control in hypofractionated RT after breast-conservative surgery among young Egyptian patients A.M.A. Omar 1 , A.M.A. Darwesh 1 1 Faculty of medicine, Alexandria University, Alexandria Clinical Oncology and Nuclear Medicine Department (ACOD), Alexandria, Egypt Purpose or Objective Since the beginning of coronavirus disease (COVID-19), there is a compelling reason for the use of hypofractionated radiotherapy (HFRT) schedules in cancer management to safeguard the patients and the treating physicians. However, conflicting data shows that young breast cancer (BC) patients have a higher locoregional relapse after breast-conservative surgery (BCS). Given this, we aim to compare the locoregional control between conventional radiotherapy (CRT) and HFRT after BCS in a cohort of young BC patients. Materials and Methods We retrospectively reviewed stage I-III BC patients in two centers diagnosed between 2008 and 2017 who underwent BCS and had follow-up data. Patients were categorized into two groups: CRT (50Gy in 25 fractions) vs. HFRT (40.5 - 42.5 Gy in 15-16 fractions). Boost was added to all patients. Results 247 patients were included in this analysis. Among them, 87 (35%) received CRT, while 160 (65%) were treated by HFRT. The clinicopathological characteristics of CRT vs. HFRT were as follows: The majority of the patients were T1 and T2, 92% in CRT vs. 94% in HFRT. N3 was rare in both groups, 8.3% vs. 5.1% in CRT vs. HFRT, respectively. The CRT had more stage 3 patients than HFRT, 35% vs. 23% respectively, but fewer stage 1 (18.1 vs. 23.5%, respectively). Estrogen/progesterone receptor (ER/PR) positive was 79.5% vs. 76.7%, HER2 enriched was 7% vs. 5%, while high Ki-67 was 56.3% vs. 71.4% in CRT vs. HFRT, respectively. Lymphovascular invasion was positive in 52.7% of CRT vs. 64.3% in HFRT, while the extracapsular extension was positive in 31% of CRT vs. 19.4% in HFRT. The distribution of tumor grades was similar across the groups. After a median follow up of 42 months (range: 5-135), 10% of the total 247 patients developed locoregional recurrences:13.8% (n=12) were in CRT group, whereas 8.1% (n=13) in HFRT, p = 0.158; the HFRT group had insignificant lower locoregional recurrences. In univariate and multivariate analysis, only very young age was an independent poor prognostic factor for locoregional failure. Conclusion We found no significant differences in locoregional control between CRT and the HFRT following BCS among young BC patients. In this COVID-19 pandemic, HFRT should also be considered in young BC patients to shorten the treatment time. PO-1111 Is Calendula useful for radiation dermatitis in breast cancer? A single-centre clinical trial. P. Blasco Valls 1 , C. Prieto Prieto 1 , M. Fernández Rodríguez 2 , G. Russo 3 , N. Mut Salud 4 , R. Gutiérrez Sánchez 5 , I. Castillo Pérez 1 1 San Cecilio Clinical University Hospital, Radiation Oncology, Granada, Spain; 2 University of Granada, Research Group on Pharmaceutical Care, Granada, Spain; 3 Laboratorio Inves Biofarm, Research and