In nonmetastatic local advanced breast cancer patients, we are going to investigate whether circulating tumor DNA (ctDNA) detection can reflect the tumor response to neoadjuvant chemotherapy (NCT) and detect minimal residual disease after surgery.

Breast cancer is the most common malignant tumor in women worldwide, and chemotherapy is still the main method of breast cancer treatment. And for locally advanced breast cancer patients, neoadjuvant chemotherapy can further improve treatment efficacy, improve prognosis and increase the rate of breast conserving surgery. The persistence of a minimal residual disease at distant sites after the treatment of a localized breast cancer is a key parameter for posttreatment survival but cannot be reliably assessed by the current biological or radiological tools. Therefore, the prediction of the chemotherapy efficacy is very important. ctDNA, corresponds to fragmented DNA released into the blood stream by tumor masses, the detection and quantification of circulating tumor DNA (ctDNA) is a very promising tool that can assess tumor burden, response to therapy, and minimal residual disease. In this study, we wil collect breast cancer cases treated with neoadjuvant chemotherapy, draw blood and evaluate the efficacy each time before chemotherapy and after surgery, then measure the concentration of ctDNA in each sample. We will also analyze the demographic data,basic treatment and follow-up data including relapse, metastasis and survival.

Inclusion Criteria:

• Patients pre- or post-menopausal must have histologically confirmed early stage/locally advanced invasive breast cancer;
• Tumor size ≥ 0.5cm (clinical or radiographic measurements);
• Any nodal status allowed;
• Age > 18 years old;
• Felt to be a possible candidate for neoadjuvant systemic therapy by their treating physician;
• ECOG score<=2;

Exclusion Criteria:

• Known metastatic disease;
• With serious heart, lung, liver diseases;
• Poor cardiac function;
• Pregnant;
• Patients with other malignant tumor or treated before;

Patients that are considered possible candidates for neoadjuvant chemotherapy, by clinical-pathologic features.