The DNA of the microbes in the blood indicates a cancer in the early stages

has long been known that the community of microorganisms living in the human gut, may influence the occurrence of cancer in the intestine, as well as in chemo – and immunotherapeutic treatment. And changes in the microbiota of human language can be an indicator of pancreatic cancer.

These and other data indicate that specific types of cancer can be associated with specific microorganisms. And their unique DNA signature (nucleotide sequences that can be used for the detection and identification of the organism) are present not only in the tissues of the neoplasms, but also in the blood. And these markers can be used for the diagnosis of cancer by a blood test, thereby avoiding more expensive and invasive biopsy.

a promising Development of the tool was carried out by scientists from the United States.

“Almost all previous cancer research has suggested that tumors are sterile environments, and ignored the complex interaction of cancer cells with viruses, bacteria and other microorganisms that live in our bodies and on them, — explains in a press release, Professor Rob knight (Rob Knight) from the University of California in San Diego. — The number of microbial genes in our body far exceeds the number of human genes, it is not surprising that they give important clues about our health.”

In the first phase of work, the researchers used the Atlas cancer genome. They studied more than 18 thousand samples of tumors in the search for microbial DNA, which can serve as a marker of a particular type of cancer. In total, the analysis covered 33 of its type.

Experts have painstakingly sorted the DNA signatures of bacterial, viral and archaeal origin.

Some of the results were expected. For example, the relation between human papillomavirus and cervical cancer, head and neck, as well as the relationship between fusobacteria and cancer of the gastrointestinal tract.

the Team identified and previously unknown Mickdetailed DNA signatures, which are significantly varied depending on the type of cancer. For example, the presence of certain types of fuzobakterii distinguished colon cancer from other types of cancer.

they Then trained hundreds of machine learning models to associate the unique genetic signatures of organisms with specific cancer types and to look for these markers in the array data obtained by analysis of blood.

the audit showed that these models do help to detect various types of cancer by microbial DNA.

moreover, the technique worked even when the researchers excluded from the data set cancer stage III and IV. This suggests that microbial markers are present in human blood at the early stages of the disease.

In the next phase, the team obtained samples of blood plasma hundred patients with cancer of the prostate, lung and melanoma. There was also a control group — 69 plasma samples taken from people without cancer.

At the first health check of concept, the results were impressive. The accuracy of identifying people with lung cancer was 86% and, not least, the tool with 100% accuracy indicated the absence of this disease in participants from the control group.

Also models good determine what type of cancer was a patient. For example, the tool was able to distinguish a person with prostate cancer from a man with lung cancer with an accuracy of 81%.

Ahead research group a lot of work. It will have to improve the technology to conduct large-scale clinical trials and, if they are successful, to bring new diagnostic tool to market. The authors hope that in the future their development will help to identify cancer at its earliest stages.

in addition, microbiologists and oncologists are going to hold a number of related studies. For example, they want to find out where exactly are microbes whose DNA serves as a marker of cancer, and whether they are alive, whether they are associated with carcinogenic processes or is it PROSTO “passengers” in the tumor tissues.

On the work done, the team reported in a paper presented in the journal Nature.

Recently, “Conduct.Science” ( reported another interesting method: Japanese scientists began to use the worms to detect 15 types of cancer.

Text: To.Science