Dr Sammons on the Real-World Incidence of Brain Metastases in HER2+ Breast Cancer

Sarah Sammons, MD, associate director, Metastatic Breast Cancer Program, Dana-Farber Cancer Institute, discusses the real-world incidence of brain metastases in HER2-positive breast cancer per line of treatment as well as cumulatively.

Brain metastases are a significant concern in HER2-positive breast cancer, with approximately 30% of patients developing them at some point during their disease course. The timing of these metastases relative to the line of therapy has not been well characterized, prompting investigators to delve into this unmet need by utilizing real-world data, Sammons begins.

A study presented at the 2023 SABCS Conference analyzed data from the US Flatiron Health de-identified database, comprising 18,075 patients, Sammons details. Of these, 3,062 had with hormone receptor–positive, HER2-positive disease and 902 had hormone receptor–negative, HER2-positive disease.

Results showed demonstrated that the prevalence of brain metastases generally differed by tumor subtype and by line of therapy across all breast cancers, Sammons reports. Notably, patients with hormone receptor (HR)–positive or –negative disease tended to develop brain metastases early, often by the third-line of therapy, she notes. The cumulative incidence of brain metastases was highest in the HR-negative, HER2-positive, and triple-negative breast cancer (TNBC) subgroups, with the HR-positive, HER2-negative subgroup experiencing the lowest incidence, Sammons details. However, due to the larger number of cases in the hormone receptor–positive, HER2-negative group, they represented the largest proportion of brain metastasis events.

These findings underscore the importance of identifying clinical and biological predictors of brain metastases and implementing strategies to prevent their onset, she concludes. Additionally, the data shed light on the impact of brain metastasis inclusion and exclusion criteria in clinical trials for patients with metastatic breast cancer, emphasizing the need for tailored approaches in trial design and patient management.