In general, brain metastases found after development of neurologic symptoms have poor prognosis. Therefore, the investigators aim to investigate whether regular brain MRI (Magnetic Resonance Imaging) can detect early brain metastases and influence survival through early brain management in HER2-positive and triple negative breast cancer.

It is well known that HER2-receptor positive and triple negative metastatic breast cancer (MBC) have poor prognosis than hormone receptor positive metastatic breast cancer. However, as new therapies such as trastuzumab and pertuzumab are introduced, overall survival was extended in patients with metastatic breast cancer compared with the previous 10 years. As a result, the number of breast cancer patients with brain metastases has increased, the demand for treatments of brain metastases is increasing.

The incidence of brain metastases in MBC has been reported to be 7.6% and 10.8% in luminal A / B, respectively. However, HER2-positive and triple negative breast cancer with the incidence of more than 30% of brain metastases were at high risk group of brain metastases.

In general, brain metastases found after development of neurologic symptoms have poor prognosis. Therefore, the investigators aim to investigate whether regular brain MRI (Magnetic Resonance Imaging) can detect early brain metastases and influence survival through early brain management in HER2-positive and triple negative breast cancer.

Inclusion Criteria:

• Patients over 19 years

• Pathologically documented breast cancer that:

  1. is unresectable or metastatic ;
  2. has confirmed HER2 positive expression according to American Society of Clinical Oncology- College of American Pathologists (ASCO-CAP) guidelines or triple negative breast cancer

• No prior systemic palliative treatment of metastatic breast cancer

• Must have provided informed consent for study participation before performance of any study-specific procedures or tests

Exclusion Criteria:

• History of prior treatments about brain metastases or leptomeningeal metastases
• Symptomatic brain metastases at screening period
• Has received more than second-line systemic treatments (including endocrine therapy)
• For subjects who have difficulty lying down or who have claustrophobia, they can undergo sedation during brain MRI
• History of hypersensitivity reaction to contrast or drug allergic reaction
• Patients who inserted metallic prosthesis (pacemaker, denture, hearing aid, aneurysm clip, metallic material of eyeball, artificial joint, insulin pump, chemo-port, temporary tissue expander for breast reconstruction, etc) can be conducted after consultation with investigator before MRI.
• Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial.
• Social, familial, or geographical factors that would interfere with study participation or follow-up

Patients who were initial diagnosed with HER2-positive, triple negative metastatic breast cancer