Colorectal cancer is now understood to be definitely linked to microbial problems in the gut.  Research has shown that the disease is linked with less numbers and diversity in the gut microbiome, and with the increased presence of more harmful strains.  Therefore using gut bacteria to diagnose and even aid in cancer prevention is highly desirable due to it’s quick, non-invasive ease of investigation.

Now, a study from researchers at University of Minnesota has predicted key genetic mutations in colorectal tumours by analyzing the types of gut bacteria present around them.  The team state that it could be possible to genetically classify the colorectal tumour a person has without having to do a biopsy and dissect it.  Their findings were presented at the American Society of Human Genetics (ASHG) 2015 Annual Meeting.

Previous studies have found associations between certain mutations and colorectal cancer, and between certain microbiome characteristics and cancer, however they have not integrated the two.  The group state that the current study was the first study to analyze both of these factors together.

The current study examined the genetic differences between colorectal tumour cells and healthy colon cells from 44 adults with colorectal cancer. The researchers looked for correlations between specific mutations in the tumour cells and the composition of the tumour microbiome, the types of bacteria present in the tumour’s immediate environment and their relative abundance, and found relationships between the two.

Results show that the more cancer-associated mutations a person’s tumour cells had, the more varied his or her tumour microbiome was.  Data findings show that specific mutations in tumour cells were associated with the presence of specific types of bacteria in the microbiome.  The lab note that on average, the method correctly predicted about half of the most common mutations found in the tumour.  The group caution that their current findings show only a correlation between microbiome composition and mutations in colorectal tumours.  They go on to conclude that they have developed a method to predict the types of mutations present in a tumour based on its microbiome.

The team surmise that by studying interactions between tumours and the bacteria in their microbiomes, the global community could better understand the bacteria’s role in causing tumours to form and grow, and may be able to treat cancer by changing aspects of its microbiome.  For the future, the team plan to study whether bacterial changes cause colorectal cancer, and evaluate whether colorectal tumour microbiome composition can be assayed from stool samples to predict the type of mutations present in the tumour cells.

Source: American Society of Human Genetics (ASHG)

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