The goal of this observational study is to explore the utility of analytical techniques that enable the study of small amounts of tumor-derived material circulating in the blood, such as fragments of circulating tumor DNA (also known as ctDNA), cells, or other particles. This type of sample is generally referred to as a liquid biopsy, and its analysis is a minimally invasive test, as it only requires the collection of blood samples. The study includes women and men with early-stage breast cancer (EBC) who are about to start neoadjuvant treatment (treatment given before surgery). The main questions it aims to answer are:
* Can liquid biopsy analyses (ctDNA) provide additional information about the type of tumor before treatment starts?
* Can these analyses help to detect early whether the tumor is responding to treatment?
* Can these tests identify if any cancer remains after neoadjuvant treatment or after surgery?
* Is this information related to the risk of the cancer coming back?
* Can these analyses, when performed during follow-up, help detect cancer recurrence earlier?
Participants will:
* Continue receiving standard medical care for their breast cancer, including neoadjuvant therapy and surgery.
* Provide blood samples at different time points during treatment and follow-up.
* Provide residual tumor samples from the routine clinical care.