Researchers at the University of Queensland, Australia have developed a blood test that can detect whether a patient has any type of cancer within as little as 10 minutes. Although still in the initial stages of testing, this cheap and simple method could help clinicians to diagnose cancer before symptoms appear, when the widest range of treatment options are available.
Cancer diagnosis relies on the ability of patients and clinicians to spot the signs and symptoms of disease, which often go unnoticed until the cancer has progressed. Screening programmes increase the chances of early detection but the currently available screening tests are expensive, time-consuming and are specific to individual types of cancer.
This cheap and simple method could help clinicians to diagnose cancer before symptoms appear, when the widest range of treatment options are available.
The new method, published in Nature Communications, claims to be able to detect the presence of cancer cells anywhere in the body using a simple and non-invasive blood test. This universal cancer test hinges on a key difference between the DNA of healthy and cancerous cells, which affects how well it binds to metals such as gold. This is a property that can be measured using a simple colour changing test.
Cells use a DNA chemical modification known as methylation to control when and where genes are switched on in the body. In healthy cells the genome is heavily coated with this methylation but in cancer cells, most of it is removed, with only small clusters of methylation remaining. The authors refer to this unique cancer methylation pattern as the ‘Methylscape’.
Professor Matt Trau, who led the research, said, “It seems to be a general feature for all cancer. It’s a startling discovery.” Co-author Dr. Abu Sina added, “Because cancer is an extremely complicated and variable disease, it has been difficult to find a simple signature common to all cancers, yet distinct from healthy cells.”
The researchers found that the ‘Methylscape’ of cancer DNA affects its chemical properties. When DNA is added to water, the methyl chemical groups cause the DNA to fold up into nanostructures. Due to the lower numbers of methyl groups, cancer DNA forms fewer of these nanostructures than healthy DNA. This means that it has a larger surface area, which allows it to bind much more strongly to metals like gold than the bundled up, healthy DNA. How strongly DNA binds to the surface of gold can be measured electrochemically or with a colour changing test, visible to the naked eye.
The authors are hopeful that their method could be used as a non-invasive screening test, as cancer DNA is not only present in tissues but is also released into the bloodstream when tumour cells die. They tested the method on over 100 blood samples from patients diagnosed with breast or colorectal cancer, and 45 samples from healthy individuals. The method was able to reliably distinguish between healthy and cancer DNA and could therefore be used to provide a simple yes or no answer as to whether a patient has cancer. The location and stage of disease would then need to be determined with further tests.
“We certainly don’t know yet whether it’s the Holy Grail or not for all cancer diagnostics but it looks really interesting”Professor Matt Trau – University of Queensland
Whilst the study has generated a lot of excitement in the media recently, the method is still in the initial stages of testing and it will be some time before it could be ready for clinical use. “We certainly don’t know yet whether it’s the Holy Grail or not for all cancer diagnostics,” says Trau, “but it looks really interesting as an incredibly simple universal marker of cancer, and as a very accessible and inexpensive technology that does not require complicated lab-based equipment like DNA sequencing.”
It is also important to note that the samples used in this research were from patients diagnosed with advanced stage cancer. The method will need to prove its sensitivity to detect the ‘Methylscape’ signature in patients with earlier stage disease, who likely have lower levels of circulating tumour DNA.
Ged Brady, of the Cancer Research UK Manchester Institute, said, “This approach represents an exciting step forward in detecting tumour DNA in blood samples and opens up the possibility of a generalised blood-based test to detect cancer. Further clinical studies are required to evaluate the full clinic potential of the method.”