Abstract PS2-06-16: Two cohorts of young women (<41y at diagnosis) with invasive breast cancer: Single center data on how demographics, tumor characteristics, therapies and 5-year survival differ when treated 2000-2005 and 2014-2019

Abstract Background: Over the past two decades, breast cancer characteristics and outcomes have improved, largely due to earlier detection through increased awareness and screening, as well as improvements in (neo-)adjuvant therapies. However, real-world data on breast cancer in women up to age 40 remain rare. Methods: This retrospective study compares demographics, tumor characteristics, therapies and 5-year survival between two cohorts of female patients with invasive breast cancer diagnosed before the age of 41 at UZ Leuven, during the periods 2000-2005 (cohort 1) and 2014-2019 (cohort 2). The Mann-Whitney U test was used for continuous variables and Fisher’s exact test for categoric variables. Significance was defined if p1% HER2 amplified, but significantly less likely lobular, grade 3, and ER