The ability to diagnose prostate cancer using microchips


A press release issued by the University of Toronto on Monday may have given many people the idea that a “BlackBerry-sized” device carrying a microchip would shortly be available as a tool to diagnose prostate cancer in less than an hour — with the ability to differentiate between high- and low-risk forms of the disease.

Unfortunately, the theoretical potential of the technology and the actual ability to accurately diagnose prostate cancer through the use of this technology remain light years apart. So let’s see if we can separate the wheat from the chaff!

What the researchers at the University of Toronto have actually done is to demonstrate the potential of a specific technology. And they have also used prostate cancer as a clinical model to demonstrate the theoretical applicability of this technology.

In  one of several papers, the most recent being a paper in Nature Nanotechnology written by Soleymani et al., this research group have shown how nanotechnology can be used to create microminiaturized nucleic acid sensors that have a broad range of sensitivities and that are capable of rapid analysis of DNA specimens. These microminiaturized “chips” can then be used to detect and identify tiny amounts of specific SNPs (“snips”) of DNA from biological samples that are associated with risk for specific diseases.

In an earlier paper, by Fang et al., the same group of researchers showed that this type of nucleic acid chip could identify, with relatively high accuracy, the presence of specific DNA SNPs found in cell extracts and tumor tissues and associated with a diagnosis of high-risk and low-risk prostate cancer. In other words, their chips could accurately detect and recognize pieces of DNA that other researchers have stated are “associated” with the presence of prostate cancers of specific subtypes.

HOWEVER — and this is a BIG “however” — what no one has been able to do yet is to clearly demonstrate that the DNA SNPs “associated” with prostate cancer are prospectively indicative (“diagnostic”) for prostate cancer. All we know at this time is that there is a high level of association with the presence of these SNPs in men who happen to have prostate cancer. Whether is association is prospectively clinically indicative of the presence of prostate cancer, or whether it is just an association with no specific clinical relevance, we just don’t know.

What we do now know is that if we can ever prove that a particular combination of DNA SNPs is prospectively diagnostic for high risk as opposed to low risk prostate cancer, and if it is easy to extract the relevant tissue and cell samples from the patient, then it should be possible to develop a BlackBerry-sized device carrying a specific set of microminiature chips which could accurately identify whether the relevant combination of SNPs was present in a specific sample. Then we might be able to use such a tool to make a preliminary and relatively accurate diagnosis of high-risk prostate cancer in less than an hour.

In the meantime, however, The “New” Prostate Cancer InfoLink thinks that there is higher potential for this type of device to be used to identify more specifically and diagnostically accurate nucleic acid SNPs (such as nucleic acid SNPs that are unique to the HIV or the HPV or other viruses) which might shorten the time to a diagnosis of specific viral diseases that may currently take days or weeks to identify using traditional laboratory culturing techniques. It is possible that in this case a blood or a urine specimen might be usable as the testable sample, making any form of invasive test to get relevant tissue samples unnecessary.

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