Women with estrogen receptor-negative and progesterone receptor-negative breast cancers who develop brain metastases have the worst overall outcomes, suggesting that aggressive initial treatment should be considered to prevent such metastases, according to a presentation at the U.S. Breast Cancer Symposium in San Antonio, Texas.

The findings came from two studies conducted at the Jacksonville, FL Mayo Clinic site.

The current research was the first to look at differences in brain metastases and survival by different breast cancer subtypes. In one of the studies, led by Stephanie Hines, MD, investigators found that the median survival from diagnosis to death in 103 women with triple negative tumors with brain metastases was 26 months compared with 49 months in women with other types of breast cancer and brain metastasis.

The second study, led by Laura Vallow, MD, looked only at HER2 receptor-positive tumors that had metastasized to the brain and concluded that median survival from initial diagnosis to death in patients with hormone receptor-negative tumors was 17.5 months compared with 55 months for women with hormone receptor-positive cancer.

"We need to be aware that this kind of cancer is high risk and we should do all that we can to prevent brain metastasis," said Hines. "For women with triple negative breast cancer, improvements in outcome will likely come when new treatments for this type of cancer are successfully developed."

Targeted therapies are available for cancers that are hormone receptor-positive or HER-receptor positive before they metastasize to the brain. Herceptin is theorized to be too large to breach the blood-brain barrier. No targeted therapies exist for patients with hormone receptor-negative tumors.

"What's needed, therefore, are treatments for HER2-positive and triple negative tumors that can reach the brain, as well as treatments that are specifically targeted to treat triple negative breast cancer cells," Hines added.

Metastatic breast cancer accounts for 20 percent to 30 percent of the 170,000 cases of brain metastases diagnosed annually, and as improvements in systemic therapy prolong survival, brain metastasis in breast cancer patients is becoming more evident, said Vallow.

"These results suggest that more aggressive therapy in hormone-negative tumors may be warranted because patients with hormone-negative disease tend to develop brain metastasis even if the cancer has not spread anywhere else, and this metastasis develops sooner and survival is shorter compared to breast cancer that is hormone receptor positive," she said.

While the outcome appears to be worse for HER2-positive, hormone-negative tumors than for triple negative cancers, findings from the two studies cannot be matched against each other because the studies did not directly compare these two groups of patients.

"One compared triple negative cancers against all other subtypes, and the other compared HER2-positive, hormone-positive cancers against HER2-positive, hormone-negative cancers/," Hines said. "We didn't directly compare outcomes from triple negative tumors against HER2-positive, hormone-negative cancer."