Detecting a disease in its early stages can reduce the impact that it has on the patient, and potentially save lives. That is why tests to diagnose a disease are about as important as the cure or treatment itself. Cancer is an obvious example where early detection matters: if a tumour remains unnoticed, it gets the chance to spread to other organs, after which treatment may be futile. Scientists from Imperial College London and the University of Vigo have created a test setup with a very high sensitivity, rendering much earlier detection of diseases possible.
The newly developed test has been demonstrated by an attempt to detect prostate cancer. For this, the scientists used a known biomarker: a molecule that indicates the presence or absence of a disease, which is used instead of attempting to observe it directly. A clearly defined biomarker for prostate cancer is PSA, a protein that is actually produced by the prostate. Because a tumour would also produce PSA, abnormally high levels indicate the presence of cancer.
When compared to conventional means of testing, the new way of detecting PSA was nine orders of magnitude more sensitive. To put it in numbers: the scientists were able to detect the protein at 0,000000000000000001 grams per millilitre. According to them, this is currently the limit for detecting molecules using their test setup. Because the actual detector is variable, the system can also be used for a variety of other diseases, which makes for a broadly applicable test.
The way the sensor works is quite different than conventional methods, even though they still use the same detection mechanism: antibodies. These are biological molecules normally produced by the immune system in order to specifically bind to, mostly foreign, molecules. Nowadays, scientists produce antibodies themselves, and they make for excellent detectors with high specificity. In the new diagnostic method, these antibodies are connected to star-shaped pieces of gold that float around in suspension. Apparently, this is enough to detect biomarkers with much more sensitivity.
|The lock-and-key mechanism of an antibody: it only binds to a specific molecule, called an antigen.|
A correct diagnosis is the first step to a cure or treatment. By detecting a disease in its early stages, a lot of lives may be saved and healthcare costs are reduced. That is why the newly developed test is very promising, also because scientists are constantly finding new biomarkers that represent presence or absence of a disease. For cancer, a recent study revealed that biomarkers can also predict how a patient responds to treatment, further illustrating the usefulness of using the presence of certain molecules as a surrogate for disease.