Have you heard about the gut microbiome? It’s getting a lot of attention these days for its possible role in colon cancer.
What Is the Gut Microbiome?
“We live in a world that is microbiotic — the oceans, soil, air and the skin and gut of the human body,” says Dr. Arthur Frankel, professor of internal medicine at UT Southwestern Medical Center. In fact, the human gut is home to roughly 150 different species of bacteria, and billions of each species. This means we have about 100 trillion microbes — just in our gut alone.
Having a good diversity of gut bacteria is important for a healthy immune system because the gut microbiota provides a natural defense barrier to infection. Although these microorganisms vary somewhat among individuals, each person’s normal diversity of bacteria remains relatively consistent over time.
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What’s the Link Between the Gut Microbiome and Colorectal Cancer?
The relationship between humans and our microbes is complex, Frankel says. Take Helicobacter pylori ( H. pylori), for example. This type of bacteria appears to play a role in the development of stomach cancer (and possibly colorectal cancer), but it also provides protection against esophageal cancer.
It’s become clear that the gut microbiome is in some way involved in colorectal cancer. In fact, scientists suspect that microbes are involved in about 20 percent of cancers, especially CRC. However, the link between the gut microbiome and colorectal cancer is complicated.
When certain environmental factors disrupt the natural balance of gut bacteria (or dysbiosis), it may play a role in the development of disease, including CRC. Frankel says we know that some organisms are associated with colon cancer, but we’re not sure yet if they actually cause colon cancer. We also know that certain types of bacteria are found in colon cancer, but are not found (or are much less concentrated) in the healthy tissue around a tumor. “This doesn’t prove an association [between the bacteria and cancer],” Frankel says, “but it provides a little more evidence [of a relationship].”
Scientists are trying to determine how dysbiosis affects risk for colorectal cancer. They have a couple hypotheses. One is that an out-of-balance gut microbiota may drive inflammation, and inflammation is a significant risk factor for cancer development. Or, the bacteria may cause DNA damage, which can lead to the development of tumors.
Many environmental factors may cause dysbiosis. Diet is a big one. A diet high in fat and red meat and low in fiber is a known risk factor for CRC. Being obese and drinking heavily are also risk factors for CRC.
Prolonged antibiotic use at an early age may also be a risk factor for CRC, says Dr. Sreeram Maddipatla, medical oncologist/hematologist for the Liver Center and Pancreas Center at UF Health Cancer Center–Orlando Health. There are few studies on this topic so far, Maddipatla says, but a study at Harvard in 2014 suggested that alterations in naturally occurring bacteria in the intestines caused by antibiotics might predispose someone to CRC or colon polyps. “You shouldn’t worry if you really need an antibiotic,” Maddipatla says. “It you need antibiotics, take them. We need more robust data to really prove the point.”
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What Are the Clinical Implications for Colon Cancer Prevention and Treatment?
At this point, the gut microbiome is an active area of research, but it’s too early — and there are still too many unknowns — for doctors to make recommendations for patients. The potential opportunities are exciting, however.
For example, we may eventually be able to add good bacteria to the gut to prevent colon cancer. Although many people take probiotics (supplements of good bacteria) to improve colon and overall health, there’s no evidence that taking current supplements will reduce your risk of colorectal cancer. Fecal microbial analysis (analyzing the bacteria in your stool) may someday provide another way to detect or screen for colorectal cancer. And, of course, the microbiome might be a target for yet-to-be-developed treatment options, or we may find ways to use it to improve the effectiveness of certain anti-cancer treatments.
In the meantime, individuals can certainly take steps to lower their risk for colorectal cancer. “Eat more vegetables,” Maddipatla says. “They have antioxidants and cancer-fighting compounds. Increase your fiber consumption. Fiber reduces the formation of polyps. Maintain adequate vitamin D levels, especially if you already have CRC. It may help prevent recurrence.” Finally, avoid processed foods and limit your red meat consumption. Diets heavy in red meat and processed foods are a significant risk factor for CRC.
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Other lifestyle changes, such as exercising regularly, drinking in moderation, not smoking and maintaining a healthy weight, can help lower your risk for colorectal cancer, too. “Obesity is linked to cancer, including CRC,” Maddipatla says. “Even a small weight loss can help, especially losing excess belly fat, which is associated with CRC.” A healthy diet and regular exercise can help you achieve a healthy weight.
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What’s the Link Between Gut Bacteria and Colon Cancer? originally appeared on usnews.com
