Researchers have developed a new technique for finding and analyzing stray cancer cells in the blood of lung cancer patients, a discovery that could lead to better treatments with fewer side effects.

This technology, developed at Massachusetts General Hospital, uses a microchip scanner called the CTC chip, about the size of a business card, to analyze a patient’s blood, tracking stray cells shed by tumors. The CTC-chip is so powerful that it can even detect a single cancer cell among one billion healthy blood cells.

This device has 78,000 posts to trap the stray tumor cells. Each of those posts is coated with a substance that acts like glue which is designed to stick only to circulating tumor cells, known by the acronym CTC.

“It’s like a pinball machine – the blood has to flow through all of these columns to get to the other side,” said Dr. Daniel Haber, director of the Massachusetts General Hospital Cancer Center and senior author of the study. “All the normal blood cells flow right through, but the very, very rare cancer cells stick to the columns.”

This research is targeted to develop an easy-to-use, highly sensitive treatment scorecard. If the number of cancer cells in the bloodstream decreases, treatment is probably working. If the number increases, it means that the tumor is growing and that its treatment requires a new approach.