Incidence of Brain Metastasis in Breast Cancer Varies by Subtype

The incidence of brain metastasis in patients with breast cancer varies by disease subtype, according to research published in JAMA Network Open.

The study showed that patients with ERBB2-positive/HR-negative breast cancer had the highest incidence of brain metastasis, and patients with ERBB2-negative/HR-positive breast cancer had the lowest incidence.

For this study, researchers analyzed data from the population health administrative databases in Ontario, Canada, and included patients diagnosed with de novo metastatic breast cancer from 2009 through 2018. 

Of the 3916 patients analyzed, 31.0% had HR-positive/ERBB2-negative breast cancer, 7.9% had ERBB2-positive/HR-positive disease, 5.1% had ERBB2-positive/HR-negative disease, and 6.6% had triple-negative breast cancer (TNBC). About half of patients (49.4%) had an unknown breast cancer subtype.

The cumulative incidence of brain metastasis was highest in patients with ERBB2-positive/HR-negative breast cancer (34.7%), followed by ERBB2-positive/HR-positive breast cancer (28.1%), triple-negative breast cancer (21.9%), and HR-positive/ERBB2-negative breast cancer (12.1%).

In all, 14.0% of patients underwent stereotactic radiosurgery or whole brain radiotherapy to treat brain metastasis. Patients treated with radiotherapy were younger (P <.001) and were more likely to have TNBC or ERBB2-positive disease than HR-positive/ERBB2-negative disease (P <.001).

The median time from breast cancer diagnosis to first radiotherapy treatment for brain metastasis was 19.8 months for patients with ERBB2-positive/HR-positive disease, 16.8 months in HR-positive/ERBB2-negative disease, 15.0 months in ERBB2-positive/HR-negative disease, 7.5 months in TNBC, and 14.1 months in patients with unknown subtypes.

The median survival from diagnosis was 19.3 months overall, 27.8 months for patients with ERBB2-positive/HR-positive disease, 26.2 months for HR-positive/ERBB2-negative disease, 22.9 months for ERBB2-positive/HR-negative disease, 8.8 months for TNBC, and 13.2 months for unknown subtypes.

These findings have “important implications” for potential future brain metastasis screening programs, according to the researchers. They suggested that patients with ERBB2-positive metastatic breast cancer may be ideal candidates for brain metastasis screening.

Disclosures: This research was supported by Eli Lilly. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Wang XY, Rosen MN, Chehade R, et al. Analysis of rates of brain metastases and association with breast cancer subtypes in Ontario, Canada. JAMA Netw Open. Published online August 12, 2022. doi:10.1001/jamanetworkopen.2022.25424