A new study suggests that microbes can reveal which mutations drive colon cancer.
In industrialized nations, the lifetime risk of developing colorectal cancer is about 5% and the lifetime risk of developing a noncancerous coon tumor that can develop into colorectal cancers is 20%.
The human colon is one of the most densely populated microbial ecosystems on the planet. Colorectal cancers affect over a quarter of a million people each year.
Researchers have determined that particular mixes of microbes are associated with both the number and types of DNA mutations the cancer carries. This discovery was made by examining bacteria growing alongside 44 colon cancer tumors and 44 healthy tissue samples.
According to researchers, colon tumors with more mutations had a more diverse mix of bacteria or microbiome than tumors with fewer mutations.
Certain bacteria were more likely to be found growing next to cancer cells carrying specific mutations.
Microbe analysis predicted with 70 to 80% accuracy when researchers would find mutations in five of 11 genes examined.
Mutations can create different environments for bacteria to grow. Tumors with mutations that cause their cells to take in more of the sugar glucose were associated with bacteria that turner on genes that could help the microbes get energy from other sources.
At the moment it is unknown whether the bacteria change in response to the cancer, of is the microbe alterations somehow promote growth of cells carrying certain mutations.
Researchers currently only have data to show that bacteria growing close to the tumor are associated with particular mutation patters. However, if the makeup of the microbiome throughout the intestines is affected by tumor mutations, stool samples could one day be used as a screening test for colon cancer.