ESTRO 2021 Abstract Book

S470

ESTRO 2021

investigate the relationship between cognitive decline and additional sub-structures in the brain. Data collection is ongoing in clinical practice and long term follow up (5 years after treatment) will be performed.

PH-0604 Hippocampal Sparing WBRT: Trade-Off Between Tumor Control And Quality Of Life? A series of 150 pts G. Corrao 1,2 , L. Bergamaschi 3,4 , V.E. Pierini 3,2 , A. Ferrari 5 , G. Piperno 3 , G. Marvaso 3,4 , G. Riva 3 , I. Cavallo 3,6 , F. Emiro 7,3 , M. Pepa 3 , M. Zaffaroni 3 , S. Gandini 8 , M.C. Leonardi 3 , F. Cattani 7,3 , R. Orecchia 9 , B.A. Jereczek-Fossa 3,2 1 IEO European Institute of Oncology, IRCSS, Radiation Oncology, Milan, Italy; 2 University of Milan, Oncology and Hemato-Oncology, Milan, Italy; 3 IEO European Institute of Oncology IRCSS, Radiation Oncology, Milan, Italy; 4 University Of Milan, Oncology and Hemato-Oncology, Milan, Italy; 5 IEO European Institute of Oncology iRCSS, Radiation Oncology, Milan, Italy; 6 Umiversity of Milan, Oncology and Hemato-Oncology, Milan, Italy; 7 IEO European Institute of Oncology IRCSS, Medical Physics, Milan, Italy; 8 IEO European Institute of Oncology IRCSS, Experimental Oncology, Milan, Italy; 9 IEO European Institute of Oncology IRCSS, Scientific Directorate, Milan, Italy Purpose or Objective Whole brain radiation therapy (WBRT) still represents the standard treatment for multiple brain metastases (BM). The hippocampal sparing WBRT (HS-WBRT) technique using Tomotherapy has shown a significantly lower memory decline in 4-months assessment compared to standard WBRT. The aim of the present study is to retrospectively evaluate intra and extra-hippocampal recurrences of disease of our HS-WBRT cohort. Materials and Methods Data were retrospectively collected from a cohort of patients (pts) who underwent HS-WBRT at a single institution from 2016 to 2021. Inclusion criteria were: 1) diagnosis of BM; 2) Karnofsky Performance Status (KPS)>60; 3) life expectancy more than 6 months; 4) available brain magnetic resonance imaging (MRI) before RT. Treatment was performed using TomoHelical scheduled in 30 Gy in 10 or 12 fractions. An additional cohort of pts with Small Cell Lung Cancer Limited Disease primaries underwent Prophylactic Cranial Irradiation (PCI) using HS-WBRT TomoHelical scheduled in 25 Gy in 10 fractions was also analyzed. Both cohorts signed a written informed consent. Oncological outcomes were clinically and radiologically assessed every 3 to 6 months after the end of HS-WBRT. Toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. Results One-hundred fifty pts matched inclusion criteria, 120 pts in cohort 1 and 30 pts in cohort 2. Most of pts (70/120, 58%) underwent concomitant systemic therapies. 62/120 (62%) had KPS 90, 41/120 (34%) KPS 100, 11/120 (9%) KPS 80 and 5 (4%) KPS 70-60. Median dose to hippocampus was 7.6 Gy (range 6.4-14.5), median volume was 2.2 cc (range 0.72-8.37) and maximum dose was 14.75 Gy (range 7.65-27.77). Thirty-two pts (27%) experienced a brain recurrence. Of them, 23 (23/32, 72%) were extra-hippocampal and 2 (6%) were