New targeted treatments have led to dramatic survival improvements for women with HER2-positive
metastatic breast cancer. However, rates of breast cancer brain metastasis for women with the disease have
not substantially declined, reported University of North Carolina Lineberger
Comprehensive Cancer Center researchers and collaborators.
"We need better therapies to prevent brain metastasis," said the
study's senior author Carey Anders, a UNC Lineberger member, an
associate professor in the UNC School of Medicine, and a co-founder of a
UNC Brain Metastases Specialty Clinic. "Treatments that have been
developed have led to a remarkable improvement in survival for
metastatic HER2-postiive breast cancer, but are not preventing the
development of brain metastasis even within two years of diagnosis."
‘Treatments have led to a remarkable improvement in survival for metastatic HER2-postiive breast cancer, but are not preventing the development of brain metastasis even within two years of diagnosis.’
The study, presented as an abstract at the 2016 San
Antonio Breast Cancer Symposium, examined the incidence of brain
metastasis after diagnosis for three groups of patients.
The researchers investigated the brain metastasis incidence in the
period after a series of drugs were approved to treat HER2-positive
metastatic breast cancer, starting with trastuzumab, also known as
Herceptin, in the United States in 1998.
Studies have shown that trastuzumab combined with postoperative
chemotherapy has increased overall survival for HER2-postive breast
cancers by 37%. It works by targeting a protein on the surface of
a breast cancer cell, human epidermal growth factor 2 (HER2), that
promotes cancer cell growth.
Researchers sought to identify the proportion of women diagnosed
with HER2 positive metastatic breast cancer who subsequently developed
brain metastases within two years of their initial diagnosis. Of women
initially diagnosed with metastatic breast cancer at the Dana-Farber
Cancer Institute between 2000 and 2007, 30% of women had
developed brain metastasis within two years of diagnosis, and this
proportion increased to 55% among women seen between 2008 and
2011. In similarly diagnosed women seen at UNC Hospitals between 2012
and 2014, 38% had developed brain metastasis within two years.
"Treatment for this disease has evolved, but we still have a lot
work to do," said the study's first author Shlomit Shachar, a former
clinical fellow at the UNC School of Medicine who works as a medical
oncologist in Haifa, Israel. "The brain is a site that needs increased
attention, both for the prevention and treatment of brain metastases."
The risk of death in patients whose breast cancer had spread to the
brain was more than twice that of patients who had experienced
metastasis to other areas of the body. Risk of death was the same for
all three cohorts of patients.
"We were surprised to see that nothing really improved with regard
to spread of disease to the brain," Shachar said, even in years after
new targeted treatments had been approved in the United States.
Anders said there are limitations in the study in that the project
compared outcomes for patients treated at two different institutions.
Larger, population-based studies are needed, Anders said, to draw
definitive conclusions about brain metastasis incidence in the targeted
treatment era for HER-2 positive breast cancer.
"We really need to think about what is allowing cancer cells to hone
to the central nervous system," Anders said. "What we want to know is:
Is there a way to add an adjuvant therapy to standard therapy to prevent