Some breast cancer patients may require regular brain magnetic resonance imaging (MRI) scans because brain metastasis may have already occurred even in the absence of any symptoms, according to new research findings.

In particular, the study confirmed that brain metastases can be detected at an early stage in patients with advanced HER2-positive or triple-negative breast cancer, raising the possibility of changes to existing clinical practice guidelines.

The research team led by Professors Son Juhyuk, Kim Gun Min, and Kim Min Hwan of the Division of Medical Oncology at Yonsei Cancer Center reported that, when regular brain MRI examinations were performed in patients with advanced HER2-positive or triple-negative breast cancer, a significant number of asymptomatic brain metastases were detected. The findings were published in the latest issue of ESMO Open, the official journal of the European Society for Medical Oncology (ESMO).

Current domestic and international clinical guidelines do not recommend routine brain MRI screening for patients with advanced breast cancer who do not show neurological symptoms. However, HER2-positive and triple-negative breast cancers are known to carry a higher risk of brain metastasis compared with other subtypes, and discussion has continued on the need for early detection.

The research team conducted brain MRI scans on 112 patients with advanced HER2-positive or triple-negative breast cancer who had no symptoms of brain metastasis and were treated at Yonsei Cancer Center between 2018 and 2023. Examinations were performed at the time of breast cancer diagnosis and at the initiation of second- and third-line treatments.

As a result, the initial screening at the time of metastatic breast cancer diagnosis revealed asymptomatic brain metastases in 9.8% of patients. With repeated regular examinations, the cumulative detection rate increased to 19.6%. Notably, of the 33 patients in whom brain metastases were identified, 22 patients, or about 67%, were diagnosed before the onset of neurological symptoms.

Patients whose metastases were detected early received treatments such as stereotactic radiosurgery (SRS), which delivers radiation without surgical incision. Cognitive function assessments conducted before and after treatment showed no significant decline, suggesting that early diagnosis and treatment at the asymptomatic stage may help preserve quality of life.

In recent years, a series of effective therapies for brain metastases has also been developed. Combination regimens based on Enhertu and Tukysa, targeted therapies used for HER2-positive breast cancer, have been reported to be effective even in patients with brain metastases.

Professor Son stated, “With the advent of anticancer agents that are effective against brain metastases, it is becoming possible to combine radiotherapy, surgery, and systemic therapy in patients detected at an early stage, creating an environment in which both prolonged survival and improved quality of life can be expected.” Professor Kim Gun Min explained, “Brain metastasis should not be regarded as a complication to be addressed only after symptoms appear, but as a condition that requires dramatic early detection and the establishment of an appropriate treatment strategy.”

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