So, your gut microbiome. It’s pretty important, right? RIGHT. It’s the largest collection of microbial communities within your body and is increasingly being recognized for its potential effect on cancer care outcomes.
There’s science that’s now showing that your gut’s microbiome may influence your risk of developing cancer, how quickly it progresses, and importantly your response to treatment including whether or not you experience medication-related toxicity.
With respect to melanoma, one of the most common and most fatal skin cancers,, we’re starting to recognize the same trends—specifically, the presence of specific microbes in your gut and whether or not you respond to treatment has been correlated in some clinical trials. In other words, having healthy microbes in your gut can improve your chemotherapy and immunotherapy response. That’s pretty crazy because your gut microbiome is directly affected by what you eat.
So, what am I saying? I’m saying that what you eat can literally determine how you respond to cancer treatment if you were to develop cancer, including melanoma.
The study referenced below showed that people with metastatic melanoma—that means melanoma that has spread beyond your skin—respond to treatment in a more meaningful way if they have microbes, compared to people who don’t respond as well. Bacteria like Faecalibacterium and Roseburia can be protective when it comes to maintaining your gut’s lining because these bugs produce a short chain fatty acid called butyrate, which allows your gut wall to remain intact. This in turn modulates your body’s immune response and enhances its ability to kill off cancer cells. Fecal transplants, where they literally take someone’s healthy poop and place it in your gut, and eating certain foods can literally restore your gut barrier and give you a better response to cancer treatment. Mindblowing, right?
Let's get into the study. It was published by a group out of MD Anderson, which you may know is the #1 cancer institute in the US, arguably the world. This group of researchers compared the gut microbiome in three different groups—healthy controls, which were employees at MD Anderson who did not have a history of melanoma; patients seen at MD Anderson between 2015 and 2019 and who had a history of early stage melanoma (stage 0 through stage 2); and lastly patients seen at MD Anderson during this same time period who had advanced or metastatic melanoma, defined as stage 3 or 4 disease. They collected information on these three different groups and ultimately tested their gut microbiomes.
So, they ended up enrolling 228 people. And, at the very beginning of the study, they collected fecal samples (literally their poop), at baseline, meaning before any treatments if they belonged to the melanoma groups. They analyzed their poop for microbial taxa, alpha diversity and beta diversity, which are basically tests that show how diverse their gut microbiomes were and specifically which groups of bacteria were present in higher numbers compared to others.
They found some interesting results. Firstly, they found a greater diversity in overall microbiome composition in controls compared to the two groups of melanoma patients. They specifically found that people without melanoma had greater numbers of healthy so called commensal gut bacteria including Bifidobacterium, Collinsella, and Adlercreutzia. In contrast, people with melanoma had lower counts of these beneficial bacteria and higher counts of pathogenic or unhealthy bacteria like Fusobacterium. The scientists remarked that greater numbers of Fusobacterium have also been found in people with colorectal cancer and inflammatory gut diseases. The people without melanoma also had greater proportions of Ruminococcus, which again is that bacteria that produces butyrate, a short chain fatty acid that keeps the colonic mucous layer intact, and your gut lining intact.
Next, they found that people with early stage melanoma compared to late stage melanoma also had differences in their gut microbial populations. Roseburia, a healthy bacterium, was found in greater quantities in the early stage melanoma group compared to the late stage melanoma group.
Lastly, they found that people with early stage melanoma had greater overall alpha and beta diversity of their gut microbiomes compared to people with late stage melanoma. This means that having greater numbers and overall diversity of microbes in your gut appear to be protective against progressing to melanoma.
So, what does this all mean? Let’s do some thinking here. Gut microbial diversity is associated with a healthy gut and an intact gut lining. Lower diversity of gut microbes is considered a dysbiotic state, and when certain species of microbes are allowed to overgrow, the gut lining can be compromised leading to impaired immunity, excessive gut inflammation, and poorer health.
This study confirms a few things—namely that having greater diversity including high numbers of healthy commensal bacteria like Bifidobacterium, Ruminococcus, Roseburia, these promote health and may be preventing you from getting melanoma. If you were to develop melanoma, having these healthy bacteria seem to be able to improve your response to melanoma treatments. Both Bifidobacterium and high dietary fiber maintain the quality of your microbiome-mediated colonic mucus, which is the protective layer between your gut lumen, which is the hollow part of your gut, and your gut lining—the single cell epithelium that separates the outside world from your insides.
On the other hand, having unhealthy bacteria like Fusobacterium appear to increase your risk of cancer, including melanoma, likely by inhibiting antitumor responses that your immune system is trying to mount against your cancer. Other studies have shown that the high prevalence of Fusobacterium in your gut impairs your gut barrier integrity and breaks down your oral-gut niche. When pathogenic bacteria like Fusobacterium overgrow, they crowd out and lead to loss of healthy bacteria like Roseburia, which would otherwise be producing butyrate, again that critical short chain fatty acid that is necessary for gut barrier homeostasis and an enhanced immune response against cancers.
So, in conclusion, a healthy gut leads to a healthy life, including a life possibly without melanoma, but certainly with a better treatment outcome if you develop melanoma.