Increased rates of brain metastases in HR–/HER2+ breast cancer
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Compared with other patients with breast cancer, those with HR–/HER2+ breast cancer have increased rates of brain metastases, according to research presented at ASCO 2021.
“We decided to look at patients with brain metastases, as this is associated with the worst prognosis compared to other types of metastases in breast cancer,” Monika Devanaboyina, a third-year medical student at the University of Toledo College of Medicine and Life Sciences, said during the presentation. “We wanted to highlight differences in subtypes to allow for better identification of individuals with brain metastases.”
Devanaboyina and colleagues evaluated 1,268 patients included in the Surveillance, Epidemiology, and End Results (SEER) Program 18 registry who were diagnosed with breast cancer brain metastases at the time of breast cancer diagnoses. They compared outcomes in these patients with an overall population of 389,696 patients with breast cancer who were included in the SEER registry. Patients were aged 20 years and older from 2010 to 2017.
Among patients included in the study, 580 were HR+/HER2–, 225 were HR+/HER2+, 176 were HR–/HER2+, and 287 were HR–/HER2–.
The researchers found that, at 13.9%, the prevalence of breast cancer brain metastases at time of diagnosis was highest among those with HR–/HER2+ disease, compared with 4.7% of all patients with breast cancer (P < .001).
They also determined that, compared with HER2– patients, HER2+ patients had increased odds of presenting with breast cancer brain metastases (HR = 2.52; 95% CI, 2.24-2.84).
Additionally, Devanaboyina and colleagues identified higher rates of brain metastases among those aged 20 to 39 years with HR–/HER2+ disease among all patients with breast cancer brain metastases, at 28%, compared with 7.6% of all HR–/HER2+ breast cancer cases (P = .001).
They also identified a similar pattern among HR–/HER2+ Black patients. In the breast cancer brain metastases group, researchers determined that these women had higher rates of brain metastases (14.3%) compared with all HR–/HER2+ breast cancer cases overall (5.9%; P < .001).
In uninsured patients, Devanaboyina and colleagues found that those with HR–/HER2+ disease among all patients with breast cancer brain metastases had higher rates of brain metastases (14.8%) compared with all patients with HR–/HER2+ disease (6.4%; P < .001).
The researchers also found that patients with T4 or N3 status who had HR–/HER2+ breast cancer brain metastases had higher rates of these metastases compared with patients in other disease subtypes.
Devanaboyina and colleagues determined, however, that median overall survival among patients with HR–/HER2+ breast cancer brain metastases was 12 months.
However, they found that the percentage of patients with breast cancer brain metastases who achieved 5-year survival was lowest among patients with HR–/HER2– breast cancer, and was highest was among those with HR–/HER2+disease.
“Overall, our study showed that patients with HR–/HER2+ breast cancer presented with brain metastases at higher rates," Devanaboyina said. “We predict that early detection could improve outcomes with better screening approaches, especially focusing on high-risk populations.”
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