Today, in many cases, a tumor diagnosed in the initial stages of the disease can be cured, with excellent chances of recovery. The situation is different for so-called advanced stage tumors: those that can no longer be completely removed by surgery, or that have now spread beyond the initial site, for which despite decades of research progress, therapeutic possibilities remain extremely limited. For this reason, prevention and early diagnosis remain the most effective strategies against cancer. And a new technique developed by researchers at the University of Bari points precisely in this direction: it is a protocol, described in the journal Plos One, which promises to make the so-called liquid biopsies much more sensitive, that is, that set of analyzes that allow to recognize the presence of a tumor through a simple blood test.
Circulating tumor cells
Liquid biopsies are analysis techniques that look for various types of molecules released by tumors in patients’ blood. Today they are mainly used to study the progression of tumors and the response to therapies, without the need to carry out a traditional biopsy, which requires a much more invasive surgical intervention. They also have enormous potential as a diagnostic tool and screening strategy, because they could help oncologists identify a tumor pathology even long before it begins to invade the body and cause symptoms in patients. But at the moment their effectiveness in this sense is rather limited, so much so that they are not used for diagnostic purposes except within specific clinical trials.
Their effectiveness depends on two factors: which substances are looked for in the blood and how much these are predictive of the presence of a tumor, and the effectiveness of the techniques used to identify them. Obviously, directly looking for the presence of tumor cells, as in traditional biopsies, is the strategy that has the greatest chance of providing diagnostic certainty. And in fact it is also possible in the blood: they are called circulating tumor cells, and they are cells that detach from the main tumors and enter the bloodstream, and from there they can reach other organs of our body and give rise to metastases. The problem is that they are extremely rare, so identifying them in a blood sample is not easy, and this significantly reduces the diagnostic reliability of liquid biopsies that look for circulating tumor cells. This is where the new study by researchers from Bari begins.
The Italian technique
The new analysis technique was developed by the University of Bari, in collaboration with the Human Genetics department of the University of Leuven and the Institute of Intelligent Industrial Systems and Technologies for Advanced Manufacturing of the Cnr. It is based on a system of slides coated with titanium dioxide (produced by a Milanese company) used to capture the cells present in the blood sample, a technology known as laser capture microdissection which allows the isolation of individual cells present on the slides, and therefore in the use of whole genome amplification techniques (or whole genome sequencing) to analyze the DNA characteristics of the cells of interest.
This protocol was tested using pancreatic and colon cancer cells mixed with white blood cells from healthy carriers. The technique allowed us to precisely recognize tumor cells, identifying the specific mutations that characterize the two forms of tumor in 85% of the cells analyzed. The effectiveness in isolating all the tumor cells present in the slides was almost 100%, an important advantage given that the very limited number of circulating tumor cells present in a blood sample is one of the main limits to their use in the diagnostic field . Promising results – the researchers assure – which could open the doors to the use of this new technique both in the early diagnosis of tumors and in other applications in which it is necessary to identify and characterize at a genetic level specific types of cells present in the blood, such as example, prenatal diagnosis carried out on circulating fetal cells.