Diagnostic Prediction Model for De Novo Metastatic Breast Cancer

The goal of this observational study is to create a tool to estimate the risk of macroscopic distant tumor spread in women with newly diagnosed breast cancer. The main question it aims to answer is: • Can a model, which combines routine medical information collected at diagnosis, accurately predict if a patient has metastasis large enough to be found during systemic imaging? Researchers will review the past medical records of participants who were treated at a university hospital. Because this study looks at past data, participants will not be asked to do any new tasks, take new tests, or change their medical care.

Inclusion Criteria: * Female sex, aged 18 years or older. * Newly diagnosed invasive breast cancer. * Case reviewed by the Multidisciplinary Tumour Board at the study site during the inclusion period (between October 1, 2018, and July 31, 2025). * No history of prior or synchronous invasive malignancies, except for synchronous bilateral breast cancer. * Intent for primary treatment and clinical management at the study site. * Availability of longitudinal clinical records throughout the 12-month follow-up period or until death. Exclusion Criteria: -Absence of baseline systemic staging.