Developing a new liquid biopsy technique for breast cancer screening.

Impact

Most U.S. women undergoing annual screening mammograms will never be diagnosed with the disease but given the persistent 12 percent lifetime risk of developing breast cancer, annual breast cancer screening is an important component of preventive healthcare for average risk women starting at age 40. Mammograms, the gold standard for breast cancer screening, are imperfect and less helpful for fast-growing breast cancers, like the estrogen receptor-negative subtypes, which grow so quickly that they are often self-detected between mammogram intervals with a lump in the breast. To improve the precision of breast cancer screening, and increase capacity for detecting breast cancer early, Dr. Brewster and her team are working to develop a new blood-based cancer detection test, known as a liquid biopsy. Ideally, this test would allow for more personalized screening, where someone with a positive blood test can be offered more frequent screening—including breast MRI—while someone with a negative blood test would be safely advised to have less frequent screening mammograms or no screening at all.

What’s next

The liquid biopsy Dr. Brewster and her team designed will look for tumor- associated exosomes. These small, membrane-bound capsules secreted by tumor cells often contain genetic material and proteins—as if the tumor cell pinched off a part of itself—and can be found in circulation. To detect exosomes, the team developed a new, specialized biochip that captures them from blood and allows them to be imaged and molecularly analyzed. To test their methods, the team has access to a unique cohort of patients who have a high risk of breast cancer and receive blood tests when they begin screening, three to four years after, and at the time of biopsy or diagnosis. In the upcoming study, the team will use samples from this cohort to 1) evaluate how well the contents of these exosomes can identify women who have breast cancer; and 2) determine the dynamics of exosome levels over time in the lead up to diagnosis. Results from this preliminary work will hopefully lead to a larger study to confirm the utility of this method.