Breast cancer subtypes linked to survival from secondary brain tumours

A study published in the open access journal Breast Cancer Research shows that patients with tumours that are negative for estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth receptor-2 (HER2) or that are HER2+/ER- appear to be most at risk from developing brain metastases. Survival is also correlated to the triple receptor status.

This is the first time that researchers have documented a possible link between breast cancer subtypes and the incidence and prognosis of brain metastases, which occur in up to one third of metastatic breast cancer patients.

A team from the National Cancer Centre in the Republic of Korea analysed data from 126 patients with brain metastases from a pool of 805 patients diagnosed with metastatic breast cancer and treated at the Centre. The presence or absence of ER, PR and HER2 were tested by immunohistochemical staining and/or fluorescent in situ hybridisation.

More than half of the patients with early (non-metastatic) breast cancer were of the luminal A subtype (ER or PR+ and HER2-). The proportion of patients with HER2+/ER- or triple-negative tumours was significantly higher among patients with brain metastases compared to the early breast cancer population, suggesting that these latter two subtypes were associated with the development of brain metastases.

The analysis also showed a correlation between the survival of patients and their triple receptor subtypes following the diagnosis of brain metastases, the survival time of which is just 3 – 6 months. Patients with luminal A (4.0 months) and triple-negative tumours (3.4 months) had a similar shorter survival time compared with luminal B (ER or PR+ and HER2+; 9.2 months) and HER2+/ER- (5.0 months) tumours.

Patients with HER2-positive tumours experienced a significant survival benefit if they were treated with trastuzumab after their brain metastases were diagnosed.

“Our study suggests that the triple-negative subtype should be added to the list of risk factors for developing BM,” remarks Jungsil Ro, the study's corresponding author. “Approximately 10-15% of all breast cancer presents this phenotype; they have a poor prognosis and are more likely to develop brain metastases. Triple receptor status can also help to predict survival even after brain metastases have been diagnosed. We now need to develop ways to screen for these subtypes and find the best ways to manage patients with this more aggressive phenotype.”