Instruments & Equipment

Microchip Detects Circulating Cancer Cells in Bloodstream

Pathologists have always wondered when technology would advance to the point where a blood sample could be used to diagnose cancer.  Now comes news reports that a device using a microchip can identify tumor cells from a blood specimen is under development.

Researchers from Massachusetts General Hospital (MGH) BioMicroElectroMechanical Systems (BioMEMS) Resource Center and the MGH Cancer Center  have developed a microchip-based device that can isolate, enumerate, and analyze circulating tumor cells (CTCs) from a blood sample.  Because of their rarity and fragility, it has not been possible to get information from CTCs that could help in clinical decision-making in the past. 

The device uses a business-card-sized silicon chip, covered with almost 80,000 microscopic posts coated with an antibody to a protein expressed on most solid tumors.  Researchers had to carefully calculate the correct speed and force with which the blood sample should pass through the chip to allow CTCs to adhere to the microposts.  The chip allows researchers to process large volumes of blood in a very gentle and uniform manner.  The chip technology does not require any preprocessing of blood samples, which could damage or destroy the CTCs.

Researchers tested the CTC-chip against blood samples from 68 patients with 5 different types of tumors - lung, prostate, breast, pancreatic, and colorectal.  116 samples were tested and CTCs were identified in all but one sample, giving the test a sensitivity of 99%.  No CTCs were found in cancer-free control patients.

"Some of these [cancer] tumors have several potential drugs to choose from," said Mehmet Tonher, PhD, senior author of a report about the CTC-chip in Nature magazine and director of the center in the MGH Department of Surgery, "and the ability to monitor therapeutic response in real time with this device, which has exquisite sensitivity to CTCs, could rapidly signal whether a treatment is working or if another option should be tried.

For laboratories, the significance of the CTC-chip is two-fold.  First, this chip signifies that technology will soon make if feasible to use blood and not tissue to identify cancer.  Second, the chip demonstrates how advances in nanotechnology now make it possible for a diagnostic device to identify a finite number of cells that heretofore would not be detected by other methods. The CTC-chip is a reminder of how new technologies are increasing the sensitivity of tests and enabling researchers and physicians to use much smaller samples to produce a diagnostic result.

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