At the time of diagnosis of breast cancer, a substantial minority of patients with human epidermal growth factor receptor 2 (HER2)-positive or triple-negative subtypes and extracranial metastases also have brain metastases, according to Boston-based researchers.
“Patients with breast cancer, even those with cancer that has spread to distant sites of the body such as the liver or lung, do not regularly undergo screening imaging of the brain to look for brain metastases,” said Dr. Ayal A. Aizer of Brigham and Women’s Hospital in Boston. “As a result, patients often come to medical attention because of new neurologic symptoms which can be debilitating, often reflecting brain metastases that are either large in size or number.”
“Treatment of such patients,” he told Reuters Health by email, “often necessitates surgery or whole brain radiation which may have been avoided if the spread to the brain was diagnosed earlier."
Dr. Aizer and colleagues examined National Cancer Institute data on more than 231,000 patients diagnosed with invasive breast cancer between 2010 and 2013 in whom the presence (or absence) of brain metastases was known at the time of diagnosis.
In total, 968 (0.41%) of patients had brain metastasis. This amounted to 7.56% of those with metastatic disease at any site, the researchers report in JAMA Oncology, online March 16.
At particular risk were patients with a hormone receptor (HR)-negative HER2-positive subtype (11.5% of those with metastatic disease) and those with the triple-negative subtype (11.4%).
Median survival in those with brain metastases was 10 months. It was longest in those with an HR-positive HER2-positive subtype (21 months) and shortest in those with the triple-negative subtype (six months).
The researchers caution that the study is limited in that, because breast cancer screening guidelines do not recommend use of brain MRI, "many patients presenting with brain metastases at diagnosis were likely symptomatic." Therefore the proportion with metastases may have been underestimated.
Dr. Aizer concluded that "certain patients with breast cancer, namely those who have HER2-positive or triple-negative subtypes and spread of the cancer to other sites of the body, are at especially high risk of developing brain metastases and that studies evaluating the role of a screening MRI of the brain, as is routinely done in most patients with lung cancer for example, are warranted."