Treatment and outcomes in breast cancer patients: A cross section study from the EUSOMA breast centre network

Introduction: The present study was designed to describe tumour features and treatments for patients with breast cancer. It also aimed at assessing the risk of distant metastases in relation to biological profiles, disease stages and treatment. Methods: Data were analysed from 81,882 patients in the EUSOMA database (disease stages at diagnosis 0-IV; median age 61 years; range 20-100 years). All patients were treated between January 2016 and December 2021 in 53 Breast Centres within the EUSOMA certification process in 13 European countries. Cases were classified as HR+ /HER2-, HR+ /HER2 + , HR-/HER2 + or HR-/HER2- and data were analysed accordingly. Results: Univariable and multivariable analyses for distant metastases were conducted on a subset of 38,119 cases with information on whether or not they had developed them. Potential determinants included sub-group type, Ki67 value, disease stage, adjuvant systemic therapies and post-operative radiation therapy. In multivariable analysis, the HR-/HER2 + and HR-/HER2- sub-groups were associated with a higher risk of distant metastases than HR+ /HER2-. Ki67 > 20 % and advanced stage disease also carried a high risk. Radiation therapy emerged as a protective factor against distant metastases. Conclusions: Present results show a large patient database offers an information stream that can be applied to reduce uncertainties in clinical practice. Database parameters need to be updated dynamically for outcome monitoring. Molecular prognostic factors, gene-expression signatures, tumour-infiltrating lymphocytes and circulating tumoral DNA should be added