ESTRO 2022 - Abstract Book

S1037

Abstract book

ESTRO 2022

Thirty-two consecutive patients for a total of 82 metachronous HER2- BCBM treated with CyberKnife were included in this preliminary analysis. Median follow up from primary surgery and SRS was 113 months (range 42-241) and 17 months (range 0-101). Median time to brain-progression from initial diagnosis of breast cancer was 78 months (range: 15-215) with 17/32 (53%) patients with both cranial and controlled-extracranial disease at the time of of SRS. Patients were treated for all brain lesions they presented, with a median of 2 lesions for each patient (range, 1 – 9). Total median SRS dose was 21 Gy (range, 18 -24 Gy) given in 1 to 3 fractions, in alternate days. Median single lesion GTV was 0.29 cm 3 (range, 0.02 – 13.22). At the last follow up available, 17/32 patients were alive (OS=53% ; 16 patients with both cranial and extracranial disease). LC was reported in 56 of the 82 treated lesions (68%; 1 and 3-years LC : 65% and 45%, respectively- Fig 1 ), while DBC (no appearance of any new intracranial lesions) was observed in 10/32 patients (31%). Univariate and multivariate analysis for correlation with demographics, tumour and treatment characteristics are ongoing. No patients experienced severe neurotoxicity (Grade 4-5 in the Common Terminology Criteria for Adverse Events) with only 5 asymptomatic radionecrosis recorded.

Conclusion Our results showed OS in line with literature and a satisfactory 1 and 3-years LC rates with almost one third of our patients alive with no appearance of any new intracranial lesions after SRS and no severe neurotoxicity in the entire population. Ongoing-statistically analysis are needed to correlate outcome with prognostic factors

PO-1229 Radiotherapy-based management of non-metastatic Inflammatory breast cancers: a retrospective study

B. Nicaise 1 , P. Loap 1 , F. Laki 2 , D. Loirat 3 , J. Pierga 3 , A. Fourquet 1 , Y. Kirova 1

1 Institut Curie, Radiation Oncology, Paris, France; 2 Institut Curie, Surgery, Paris, France; 3 Institut Curie, Medical Oncology, Paris, France Purpose or Objective Inflammatory breast cancer (IBC) is a rare clinicopathological presentation of breast cancers (BC) characterized by diffuse tumor emboli in dermal lymphatic vessels. IBC have a poor prognosis compared with non-inflammatory BC, and treatment of non-metastatic IBC usually includes neo-adjuvant chemotherapy (NACT), followed by total mastectomy and adjuvant radiotherapy (RT). This retrospective study aims to describe the clinical outcomes of non-metastatic IBC patients treated with this multidisciplinary approach Materials and Methods This single-center retrospective study included all women diagnosed with non-metastatic IBC between 01/2010 and 01/2018 at the Institut Curie and treated with NACT, surgery and RT. Overall survival (OS), disease free survival (DFS) and locoregional free survival (LRRFS) were calculated from time of diagnosis. Prognostic factors for patient survival were analyzed based on univariate and multivariate regressions. Results 113 pts were treated for a non-metastatic IBC with NACT, RT with or without surgery (Table 1). Median age was 51 yrs, 79.7% of pts had N+ tumors, median Ki67 was 40%, 60.2% had grade III tumors; triple-negative breast cancers (TNBC) represented 34.6% of cases. A large majority of pts (91.2%) received adjuvant post-mastectomy RT (Table 2) and only ten pts (8.8%) received pre-operative RT; 17 pts (15%) received concomitant chemo-radiotherapy (mostly with 5FU-vinorelbine). Surgery was conducted in all but one patient (97.3%) and usually consisted of a total mastectomy (96.5%) with an axillary