Cancer detection

A test for cancer is being pioneered by researchers at PurdueUniversity. The test is unique in that it does not require a blood sample: a laser is used to reveal and count circulating tumour cells in surface veins. This means the process is less invasive and can evaluate a much larger volume of blood.



In addition to being less invasive, the new detection method is able to evaluate a much larger volume of blood than what can be drawn from a patient for analysis, said Philip Low, Purdue’s Ralph C. Corley Distinguished Professor of Chemistry.



‘In the initial stages of cancer, there are very few circulating tumour cells – cells that indicate the spread of cancer and initiate secondary tumour formation,’ Low said. ‘By increasing the volume of blood analysed, we improve the sensitivity of the test and allow for earlier diagnosis.’



The technique could provide doctors and patients results in a matter of minutes and save the medical industry millions of dollars in testing equipment, said Wei He, a graduate student in the Department of Chemistry and the Department of Biomedical Engineering.


By directly labelling tumour cells while they are in the bloodstream, some of the costs and problems associated with testing drawn blood samples can be avoided, He said.


The technique uses a fluorescent specific-specific probe that labels tumour cells in circulation. When hit by a laser, which scans across the diameter of the blood vessel 1,000 times per second, the tumour cells glow and become visible. The in vivo flow detection was performed on a two-photon fluorescence microscope in the lab of Ji-Xin Cheng, an assistant professor of chemistry and biomedical engineering. The researchers compared several methods and found two-photon fluorescence provides the best signal to background ratio. The technology is able to scan every cell that is pumped through the vessel, He said.


Low’s team has developed two labelling agents that attach to different forms of cancer. One label targets ovarian, non-small lung, kidney and endometrial cancer, and the other targets prostate cancer.


These labels would be administered through an injection. The first label has already been tested in humans and has no adverse side effects and could potentially be administered weekly, He said.


Computed tomography, or CT, scans and magnetic resonance imaging, or MRI, are the current methods used to track the spread of cancer. These methods have a limited resolution, and a 1mm tumour could go undetected by CT or MRI. The Purdue-developed technology can achieve single-cell resolution and can reportedly detect rare cell populations.