Gut bacteria, colon cancer link holds promise of new treatments

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Researchers identified two bacteria linked to colon cancer in its early stages, a finding that could lead to new and less-intrusive techniques for battling the most common cancer in Japan.

“The latest study is the first step into a new age of cancer prevention and treatment selection based on differences in (levels of) bacteria found in the large intestine,” team member Shinichi Yachida, a genome biology professor at Osaka University, said.

The team, which published the results in U.S. science journal Nature Medicine on June 7, also included researchers from the National Cancer Center (NCC) and other institutions.

Colorectal cancer is the most frequently diagnosed cancer among Japanese, with about 150,000 people found to have the disease every year.

However, current detection methods are mainly limited to checking for blood in stool samples and the use of intrusive endoscopes.

Various studies in recent years have focused on the human gut microbiome, a “community” in the intestinal tract comprising about 40 trillion bacteria of about 1,000 different types.

The research team conducted a comprehensive DNA analysis of feces collected from 616 patients in their 20s to 90s who underwent a colonoscopy at NCC.

Analysis results showed that those diagnosed with early-stage cancer, such as polyps that can be removed by endoscopes, had double to triple the rates of two types of bacteria compared with healthy individuals.

The bacteria in question–atopobium parvulum and actinomyces odontolyticus–are also found in large numbers in the mouth.

Differences were also found in amino and bile acid levels in feces between those with early-stage cancer and healthy individuals.

While early-stage cancer cells can typically be removed using an endoscope, patients must endure having the device and connecting tube inserted into the anus after a purgative is used to empty the large intestine.

The government’s current guideline for colon cancer detection urges those 40 and older to submit stool samples to check for blood. However, for every 10,000 people who submit the samples, 500 to 1,000 require testing using endoscopes, with only between 10 and 15 patients ultimately diagnosed with cancer.

With further research on the gut microbiome and metabolites, methods could be found to more efficiently determine which individuals require endoscope testing by analyzing the feces, leading to greater accuracy in early-stage cancer detection.

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