A new lab on a chip -- slightly more than 1.5 square inches in area -- detected circulating cancer cells in 115 of 116 blood samples from patients with metastatic cancer for a sensitivity of 99.1%, according to Daniel Haber, M.D., director of the Massachusetts General Hospital Cancer Center, and colleagues.
I have proposed widespread use of biomarker tests to help with improving public health, lower the cost of medicine, and improving medical research. The first part of the use of a lot more labs on a chip and more capable chips for biomarker monitoring is here. It is related to x-CEO of Intel Andy Grove's proposals for better medicine.
And it found no cancer cells in the blood of healthy volunteers, for a sensitivity of 100%, the researchers reported in the Dec. 20 issue of Nature.
"Clearly this has tremendous potential for early diagnosis," Dr. Haber said, but it also has the potential to allow physicians to monitor the success or failure of treatment more closely and to begin to solve some of the puzzles that surround metastasis.
Cancer kills about 1 in 7 people in the world. 7.6 million people will die in 2007 out of a total of 55 million deaths from all causes. There are 12 million new cases of cancer worldwide in 2007.
Current approaches use complicated analytic techniques -- including centrifuging and washing samples -- that generate very low yield and purity, they said.
In contrast, their "microfluidics" approach is highly sensitive, has a 99% yield, and a purity approaching 50%, compared with less than 1% for other methods, the researchers said.
The development of the chip "bring[s] us closer to having a fully automated instrument that can detect circulating tumor cells with exquisite sensitivity," said Jonathan Uhr, M.D., of the University of Texas Southwestern Medical Center in Dallas, writing in an accompanying comment.
Dr. Uhr said such a device "would allow routine monitoring of blood for tumor cells as part of a medical examination, and could result in early detection and treatment."
The researchers said that a number of engineering challenges remain before the system can be used for clinical applications, although it could be used now for research.
Microchips have been used for a range of analytic chores, such as flow cytometry, but have not been applied to tasks where milliliter-sized samples of whole blood must be analyzed, he and colleagues noted.
On theoretical grounds, they concluded that a microchip array of 78,000 tiny silicon posts -- coated with an antibody to a molecule specific to tumor cells -- would overcome that barrier.
"Much of cancer [drug] treatment now is trial and error," Dr. Haber said. The chip might potentially allow doctors to find the correct treatment more quickly.
One advantage of the system, Dr. Haber said, is that captured cells remain alive, opening the door to more detailed understanding of how they function and perhaps what causes some to become the root of new cancers while the majority commit cell suicide.