1. Lester J. Rosario BIOL3095
October 1, 2010
Summary
A Chip against Cancer: Microfluidics Spots Circulating Tumor Cells
Today people undergo treatments with fear of being harmed; especially cancer patients.
A group at Massachusetts General Hospital is currently refining and testing a lab-on-a-chip that
can sample and analyze the circulating tumor cells from just a teaspoon of a patient’s blood,
avoiding the dangerous biopsies. Most carcinomas shed malignant cells that enter the
bloodstream and disseminate, latching on to new areas and forming tumors. These cells are
called “circulating tumor cells”(CTCs), and their presence in the blood constitute fewer than one
in a billion, in patients with metastatic cancer. Scientists have adapted microfuidics technology
to analyze tiny amounts of fluid and gas, to capture those uncommon cells. The CTC-ship
comprises a silicon-etched chip fitted with microscopic columns, a chamber to enclose the fluid
and the chip, and a pneumatic pump. The columns (microposts) function as minature test tubes
where cells and chemicals mix, adhere and undergo evaluation. The CTC-chip has 78,000
microposts to grab cancer cells from the blood as it meanders through the system via exquisitely
controlled suction. The posts are coated with antibodies to the epithelial cell adhesion
(EpCAM), that it is what almost all carcinoma cells bear at the surface. Normal blood cells lack
EpCAM, so only the malignant cells bind to it. The researchers used blood samples of 116
patients with lung, prostate, pancreatic, breast or colorectal cancer and successfully isolated
CTCs in all but one case. In another research, scientists used the chip to evaluate tumor genetics
in 27 patients with lung cancer. They identified abnormalities in CTCs in almost all cases, and
noted emerging mutations in some patients that confer resistance to the medication they were
taking. Through a biopsy it would have been necessary to repeat the test in order to identify all
these abnormalities. Also a small biopsy bears risk of blood loss, infection and, in rare instances,
collapse of the affected lung. At Mass General, the researchers are evaluating the effectiveness
of the chip for the treatment of patients with breast, ovarian and prostate cancers. Mehmet Toner,
leader of the team that engineered the device, sees unlimited possibilities once this chip is proved
in bigger clinical studies. In the future, he remarks, it could be a screening tool to find nascent
cancers and “could be used at annual checkups.”