One in a Billion
Those can be the odds of finding a new technology developed at cancer cell in a sample of blood. Dana-Farber is making it possible.
By Robert Levy
Using the Rare Event Imaging System, or REIS, researchers at Dana-Farber produced this image of a cluster of epithelial cells, which form the lining of organs and glands. It represents the first time such a cluster has been detected in normal blood. Researchers believe clusters like this may be an early sign of tumor spread.
How can doctors determine whether a patient being treated for cancer is likely to survive? The amount that a tumor shrinks isn't always a good indicator. Nor are the blood levels of tumor-related proteins that have been studied so far.
But suppose it were possible to examine each of the billion or so cells in a test-tube-size sample of a patient's blood to see if any of them — even one — was cancerous and capable of forming the kernel of a new tumor. Physicians might then have a way of measuring which patients are at greatest risk for relapse and could most benefit from aggressive therapy.
The REIS image at left shows a single breast cancer cell (with a pink rim, in the lower left-hand corner) in a sea of normal blood cells. The image at right reveals a group of small cell lung cancer cells (with a light green halo) amid thousands of normal blood cells. Among the Dana-Farber researchers who contributed to making these images are Stine Kraeft, MD; Lyndsay Harris, MD; and Ravi Salgia, MD, PhD.
The size of the job is daunting, beyond the capacities of even the most advanced cell-scanning devices known as flow cytometers. But, as the images on these pages show, such needle-in-a-hundred-haystacks detective work is now not only possible but practical. The images, made with a breakthrough technology called REIS — for Rare Event Imaging System — depict cancer cells in vibrant colors amid a sea of normal, blue blood cells.
Lan Bo Chen, PhD, (right) is on the hunt for cancer cells with (left to right) Danielle Bergsrud, Jane Kepros, and Andras Ladanyi, MD.
Dana-Farber's Lan Bo Chen, PhD, and his colleagues in the Department of Cancer Biology have adapted REIS to detect otherwise-hidden leukemia, lung, breast, and esophageal cancer cells in blood samples. The system, which combines high-speed cell-sorting technology, computerized data analysis, and digital photography, "enables us to find these cancer cells — which may be present in ratios of 1 for every 100 million normal cells — photograph them, and store the images for study," Chen says.
Blazingly fast as the system is, it is still too slow and expensive to be used for routine patient screenings (it currently takes a full day to process one sample of blood). Ideally, researchers hope to refine this technology to the point where it's capable of scanning a billion cells in 10 seconds. To do that, they're exploring technology originally developed for the Hubble Space Telescope and everyday laser printers.
The system enables investigators to find elusive cancer cells, photograph them, and store the images for study.
"These images are proof of the system's ability to pick out cancer or other rare cells in the bloodstream," Chen says. "The challenge now is to speed it up sufficiently so it can become a practical tool for diagnosing cancer and other conditions."
