Conventional biopsy and surgical tumor resection are invasive procedures that capture only one instance of the progression of the tumor. However, the genome of tumor is not static, but it is constantly altered during treatment.

Liquid biopsy is a non-invasive approach based on the extraction of information through peripheral blood analysis. It makes it possible to characterize the development of a solid tumor in real time, through detailed molecular analysis of circulating genetic material in peripheral blood.

Conventional biopsy and surgical tumor resection are invasive procedures that capture only one instance of the progression of the tumor. However, the genome of tumor is not static, but it is constantly altered during treatment.

Liquid biopsy is a non-invasive approach based on the extraction of information through peripheral blood analysis. It makes it possible to characterize the development of a solid tumor in real time, through detailed molecular analysis of circulating genetic material in peripheral blood.

Study procedure:

1. Initial Visit (V0-Baseline): For the purposes of the study the following information will be collected: the demographics, medical and social history, the characteristics of the disease (stage, molecular characterization e.t.c) and the treatment regimen that is followed. As part of the visit, 20 mL of peripheral blood will be drawn prior to their treatment according to physician's suggestion as per common clinical practice. Blood samples will be then sent to ACTC laboratory for plasma/CTC isolation, DNA and RNA extraction and subsequent test for biomarkers. Primary tumor tissue samples will be also collected
2. Follow-up visit (V1): Response to treatment by RECIST based on restaging CTs/MRIs will be documented during this visit, which will take place 3 months after treatment initiation. As part of the visit, 20 mL of peripheral blood will be drawn.

Blood samples will be then sent to laboratory for plasma/CTC isolation, DNA and RNA extraction and subsequent test for biomarkers. Survival status and clinical response (CR, PR, SD, PD) will be also documented.

Inclusion Criteria:

1. Female aged ≥ 18 years of age.
2. Histological confirmed ER+/HER2- metastatic Breast Cancer prior to beginning a treatment
3. Life expectancy permits participation to the study.
4. Available tumor tissue sample for molecular analysis.
5. Signed informed consent form.

Exclusion Criteria:

1. Female younger than 18 years old.
2. History of another malignancy within 3 years or current 2nd primary malignancy.
3. Patients that have not signed the informed consent.

120 with metastatic breast cancer 30 healthy subjects