Early detection is crucial in colorectal cancer – for whom regular preventive examinations are particularly important, a new test procedure could soon reveal, researchers report: The risk of illness in a person can be determined using seven microRNAs in the blood. The detection of these biomarkers shows the tendency to develop colon cancer more clearly than previous methods for risk assessment. The method could thus help to make prevention of this common type of cancer more effective in the future, say the scientists.
Detected early, danger averted – in comparison to many other tumor diseases, preventive examinations can prevent the development of colon cancer: With a colonoscopy, the tumors and their precursors can be identified early and sometimes removed immediately. From the age of 50 for men and 55 for women, the health insurance companies also cover the costs of the preventive colonoscopy. But many people shy away from the unpleasant procedure and hope for their luck not to be affected. Unfortunately, the risky avoidance behavior often puts life in danger: “Colon cancer is still diagnosed every year in almost 60,000 people in Germany,” says Hermann Brenner from the German Cancer Research Center in Heidelberg (DKFZ).
According to him, more targeted warnings could be helpful to increase preparedness: “If we had the opportunity to better show the personal risk of disease, colon cancer prevention could perhaps be much more effective,” said Brenner. There have already been approaches to this: Certain genetic factors and people’s lifestyles are known that are associated with an increased risk of colon cancer. However, their use in the context of a risk profile for forecasting is limited. Therefore, Brenner and his colleagues looked for alternative ways to determine a person’s individual risk of colon cancer. So the possibility of detection via micro-RNAs came into the sights of the scientists.
The tiny nucleotides as biomarkers
These are nucleotide molecules that consist of only 20 to 25 building blocks. It has been known since the 1990s that these microRNAs (miRNAs) play an important role in the body. Unlike their relatives, the RNAs, they are not used directly for the production of proteins. But they play a central role in the complex process of gene regulation in the body. Studies have already shown that certain diseases are reflected in an unusual pattern of microRNAs in the blood. Against this background, Brenner and his colleagues have now investigated the extent to which certain miRNA expression patterns are related to the occurrence of colon cancer and thus enable a prediction of the disease risk.
The scientists targeted 41 miRNA candidates that, based on previously obtained evidence, seemed promising. They examined their occurrence in stored blood serum from participants in the so-called ESTHER study. This is an extensive longitudinal study on cancer research that has been carried out since 2000. As the team reports, a total of 198 of the nearly 10,000 ESTHER participants had developed colorectal cancer within 14 years of having their blood drawn. In this way, the researchers were able to examine which of the 41 miRNA candidates had shown a conspicuous occurrence in those affected.
Basis for more effective early detection
In the end, they identified seven miRNAs that were closely correlated with the occurrence of colon cancer. By comparing the values with cancer-free participants, they developed a risk score system in which the individual colorectal cancer risk is reflected on the basis of the seven miRNAs. “Our data show that changes in the miRNA profile can precede the disease by years,” says first author Janhavi Raut from the DKFZ.
Specifically, the scientists were able to show that study participants with the highest values of the miRNA risk score had an approximately 20-fold higher risk of developing colon cancer than those with the lowest values. As they emphasize, the predictive power of the method is significantly higher than that of the most informative genetic risk score to date. It is based on the detection of 140 so-called single nucleotide polymorphisms – variations of genes that are associated with an increased tendency to develop colon cancer. According to the scientists, this detection method only shows a maximum four-fold increased risk for the development.
According to them, there is considerable medical potential for their miRNA method: “It is a very promising way of assessing the individual risk of colon cancer better than was possible with previously available methods. If the predictive power can be confirmed in independent studies over a long period of time, we would have a meaningful biomarker available that could significantly improve colorectal cancer screening, ”concludes Brenner.
Source: German Cancer Research Center, specialist article: Nature Communications, doi: 10.1038 / s41467-021-25067-8