Microchip blood test detects cancers earlier

Dec 20 2007

A new blood test which uses microchip technology may offer doctors the opportunity to detect cancers earlier and also monitor cancer treatment.

The test sifts through the blood searching for circulating tumor cells (CTCs), which originate from solid tumors and roam around the body via the blood.

The test was developed by a team of researchers at Massachusetts General Hospital and Harvard Medical School and they say it is a new and effective tool with "broad implications" for cancer research, detection, diagnosis and management.

According to the scientists CTCs only account for one in a billion in cancer patients' blood and they say they have developed a counterintuitive approach for detection.

This approach involves using a tiny chip with critical geometrical features smaller than a human hair to process large volumes of blood in a very gentle and uniform manner.

The device uses a business-card sized silicon chip which has microscopic posts that are coated with antibodies that recognize cancer cells and as the blood flows over the chip, these posts act like glue, trapping cancer cells and leaving blood cells behind.

When the CTC blood test was trialled on 116 cancer patients, including people with lung cancer, breast cancer, prostate cancer, pancreatic cancer, and colon cancer, it spotted CTCs in the blood samples from 99% of the cancer patients.

The test detected CTCs even when there were only 5 CTCs in a milliliter of a patient's blood and found no CTCs in blood samples from 20 healthy people.

The researchers also used the blood test to monitor changes in CTC levels in cancer patients undergoing treatment and was sensitive enough to detect changes in circulating tumor cell levels during treatment, with drops in detected CTC levels matching tumor shrinkage seen on standard CT scans.

Dr. Daniel Haber who worked on the study says the approach raises the possibility of rapidly and non invasively monitoring tumor response to treatment, allowing changes if the treatment is not effective, and the potential of early detection screening in people at increased risk for cancer.

Dr. Mehmet Toner, of Massachusetts General Hospital whose group developed the device says 9 out 10 deaths in cancer are due to the metastatic process because the cancer spreads to other parts of the body; he says the technology will allow for much more personalized cancer care.