When treating a breast cancer patient, it’s only natural that a physician would focus fully on the main tumor, recommending therapies that target that tumor’s traits. But if that tumor begins to spread, or metastasize, through the bloodstream to other sites in the body, it can change.

In fact, 25 to 50 percent of metastatic tumors have characteristics different from the original tumor. And that spells trouble for the patient and physician because treatments might not work as well against the new tumors as they would against the original breast cancer.

George Somlo seeks better strategies for breast cancer. (Photo by p.cunningham)

Fortunately, researchers at City of Hope and Palo Alto Research Center (PARC) may have found a way to gain the upper hand. They’re studying circulating tumor cells that are moving through the bloodstream, checking their molecular characteristics to see if the information could help physicians choose better treatment strategies.

To examine the cells, they’re using a tool developed at PARC called Fiber Array Scanning Technology, or FAST.

“What’s novel in our approach is that we’re not just trying to find these cells, but also characterize them to find out how we can treat patients according to the variations between circulating tumor cells and the primary tumor and metastatic sites,” said George Somlo, M.D., co-director of City of Hope’s Breast Cancer Program.

Patients with metastatic breast cancer typically survive less than two years. According to Somlo, about 40,000 people die from breast cancer every year in the U.S. due to complications from metastatic sites. He sees a clear need to improve the ability to deliver individualized targeted therapies.

In an effort to reach that goal, the researchers took blood samples from newly diagnosed or relapsed stage 4 metastatic breast cancer patients before they began treatments or changed therapy. Then the researchers sent the samples to PARC for FAST processing and to check for key target proteins that might affect treatment choice.

Somlo noted that studying patients’ circulating cancer cells could help physicians better understand what drives each patient’s metastatic tumors. Even better, it may let doctors select therapies more likely to work against a patient’s specific metastatic cancer.