“The Gut Microbiome and Cancer”

“The Gut Microbiome and Cancer” (Michael Liss, MD, PhD) [#128] Brad Power and Kayla Yup January 22, 2025 “Hopefully I gave you a little bit of Gestalt on what's coming and how your microbes can interact with your immune system and how you can manipulate it with your diet and things like that that are coming.

It's always a sensitive topic in that you have to be careful, especially with patients that are in the cancer journey, because it's a vulnerable time and you're looking for stuff. I want to make sure that I'm an advocate for you when you're looking at the microbiome and making sure we're not overselling something.

Because this is a vulnerable spot, we need to make sure we're making good recommendations and doing good research to make sure that you are benefiting.” – Michael Liss, MD, PhD, MAS, MBA, FACS Meeting Summary Cancer is a complex disease that can be caused by a variety of factors, including: your genetics (e.g.

, gene mutations, such as BRCA1 and BRCA2); environmental factors (exposure to harmful substances in the environment, such as chemicals in tobacco smoke, ultraviolet rays from the sun, and asbestos); infections; lifestyle factors (being overweight or obese, not having a healthy diet, not getting enough physical activity, or drinking alcohol); hormones; and stress or a poor mental health state.

Beyond the prevention of cancer, patients also have challenges with managing cancer symptoms, such as pain, depression and anxiety, fatigue and weakness, loss of appetite, weight changes, nausea and vomiting, constipation. Both the prevention of cancer and the management of cancer symptoms can be influenced by your gut microbiome.

Your microbiome regulates cancer initiation, progression, and responses to therapy. An altered microbiome has been tied to specific types of cancer and to the effectiveness of cancer treatments, suggesting that the profile of your microbiome could be a biomarker for your cancer diagnosis or prognosis.

According to research from the American Cancer Society, approximately 40% of cancer cases in the United States are linked to modifiable lifestyle factors, meaning they could potentially be prevented through lifestyle changes. Lifestyle choices, particularly diet and exercise, significantly impact the microbiome, which in turn can influence your development and progression of cancer.

Michael Liss, MD, PhD, is uniquely qualified to lead a discussion about the role of the microbiome in cancer, especially prostate cancer. He is a urologic oncologist (a doctor who specializes in diagnosing and treating cancers of the urinary tract and male reproductive organs), and has a PhD in translational science, with a focus on natural products and the microbiome.

He has a masters degree in clinical trials and is a professor at UCSD. What is the microbiome?

“The Gut Microbiome and Cancer” (Michael Liss, MD, PhD) [#128]

urinary tract and male reproductive organs), and has a PhD in translational science, with a focus on natural products and the microbiome. He has a masters degree in clinical trials and is a professor at UCSD. What is the microbiome?

“The Gut Microbiome and Cancer” (Michael Liss, MD, PhD) [#128] The microbiome is the collection of microorganisms that live on or inside a person, animal, or plant. These microorganisms include bacteria, viruses, and fungi. The microbiome is dynamic and changes over time in response to environmental factors like diet, exercise, and medication.

How can the microbiome influence your development of cancer (for good or bad)?

The microbiome, particularly the gut microbiome, can significantly influence cancer development by either promoting tumor growth through inflammation and harmful metabolites produced by certain bacteria, or by suppressing tumor development through immune regulation and anti- tumorigenic metabolites produced by beneficial bacteria, essentially acting as a double-edged sword depending on the microbial composition and balance present; a disrupted microbiome is often linked to increased cancer risk.

Your microbiome can promote cancer through: ●Inflammation: Certain bacteria can trigger chronic inflammation in the gut lining, which can create a favorable environment for tumor development. ●Toxins: Some bacteria produce toxins and small molecules (metabolites) that are created when food, drugs, or chemicals are broken down that can directly damage DNA and promote cancer cell growth.

●Immune modulation : By influencing immune cell function, certain bacteria can suppress anti-tumor immune responses, allowing cancer cells to evade immune surveillance. Your microbiome can fight cancer through: ●Immune system support : A balanced microbiome can stimulate the development and function of immune cells, which can help detect and destroy cancer cells.

●Anticancer molecules : Some bacteria produce compounds that can directly inhibit tumor cell growth and proliferation. ●Barrier function: A healthy microbiome can help maintain the integrity of the gut lining, preventing harmful substances from entering the bloodstream and promoting overall health. What steps can you take to influence your microbiome?

●Diet: Try to eat 30 different types of vegetables per week: celery, green beans, spinach, etc. That is the easiest way to not only get all your vitamins, but increase the diversity of bacteria in your gut. You don't have to take any probiotics. ●Prebiotics: Prebiotics are non-digestible fibers that function as a food source for your gut bacteria.

Some studies found that intake of non-digestible fibers was inversely associated with prostate cancer risk. To increase the count of prevotella, a favorable type of bacteria, in your gut, you can eat fermented foods.

“The Gut Microbiome and Cancer” (Michael Liss, MD, PhD) [#128]

r gut bacteria. Some studies found that intake of non-digestible fibers was inversely associated with prostate cancer risk. To increase the count of prevotella, a favorable type of bacteria, in your gut, you can eat fermented foods.

“The Gut Microbiome and Cancer” (Michael Liss, MD, PhD) [#128] ●Probiotics: Probiotics are live microorganisms that benefit the health of a host. Not all probiotics sold on the market are effective, so it is important to look out for a few factors when vetting products.

Take note of CFU counts (the number of viable bacteria in a sample), the variety of bacteria included, and the ability of the bacteria to survive past the stomach acid (do they have delayed release capsules?) Some types of probiotics could be used to increase the count of Bifidobacterium. ●Postbiotics: Postbiotics are beneficial compounds produced by bacteria.

It has been shown that Lactobacillus paracasei-derived postbiotics are capable of preserving the intestinal barrier integrity. What’s next in microbiome research? ●Use the microbiome for personalized treatment and to manage side effects. ●Develop predictive models.

●Explore using vaccines to target specific microbes in the prostate ●Investigate the use of fecal transplants to boost immunotherapy response in prostate cancer ●Develop rationally designed microbial consortia for cancer treatment ●Continue research on the impact of the microbiome on treatment side effects, such as GI symptoms ●Conduct further studies on the use of probiotics and prebiotics to manipulate the gut microbiome for cancer outcomes How can you learn more?

●Contact Dr. Liss at liss@health.ucsd.

edu ●See other discussions that touch on the microbiome: ○"Terrain and the Whole Person in Cancer Care” (Nasha Winters, ND, FABNO) [#95 ] ○“Starving Cancer - Beyond the Metro Map” (Jane McLelland) [#113] ○“Remote Monitoring and Deep Data” (Mike Snyder) [#52] ○“Precision Medicine, AI, and Metabolic Interventions for Cancer Control" (Chris Gregg) [#53] The information and opinions expressed on this website or platform, or during discussions and presentations (both verbal and written) are not intended as health care recommendations or medical advice by Cancer Patient Lab, its principals, presenters, participants, or representatives for any medical treatment, product, or course of action.

You should always consult a doctor about your specific situation before pursuing any health care program, treatment, product or other course of action that might affect your health.

“The Gut Microbiome and Cancer” (Michael Liss, MD, PhD) [#128] Meeting Notes KEYWORDS Gut microbiome, prostate cancer, dietary changes, fecal transplant, immune system, microbiome diversity, B vitamins, inflammatory bowel disease, probiotics, natural supplements, cancer treatment, microbiome research, dietary recommendations, microbiome testing, cancer prevention. SPEAKERS

YWORDS Gut microbiome, prostate cancer, dietary changes, fecal transplant, immune system, microbiome diversity, B vitamins, inflammatory bowel disease, probiotics, natural supplements, cancer treatment, microbiome research, dietary recommendations, microbiome testing, cancer prevention.

SPEAKERS Michael Liss (91%), Allen Morris (4%), Brad Power (3%), Robb Owen (3%) CHAT CONTRIBUTORS Allen Morris, Roger Royse, Alane Watkins, Rick Davis, Chad Magnussen, Cindy Ness, Vic Paglisotti, David Plunkett, Tom Binnings, Brad Power, Robb Owen SUMMARY Dr. Michael Liss from UC San Diego discussed the gut microbiome's impact on cancer, particularly prostate cancer.

He explained the concepts of Alpha and Beta diversity in microbiomes and how dietary changes can influence bacterial mechanisms. Liss highlighted a 2017 study showing differences in gut microbiomes between cancer patients and healthy individuals, noting the role of B vitamins and dietary components.

He also discussed potential therapeutic approaches like fecal transplants and probiotics, emphasizing the need for rigorous research and individualized treatment plans. Liss stressed the importance of a balanced diet, including 30 different vegetables weekly, to support gut health and overall well-being. OUTLINE Introductions ●Dr.

Michael Liss is a professor at UCSD and director of clinical trials for the Center of Microbiome Innovation. ●He discussed the gut microbiome and its impact on cancer, particularly prostate cancer. Overview of the Gut Microbiome ●Microbiome research started in the 1800s to examine gut bacteria. ●Biomes are a biological concept. ●Different environments (e.g., gut, skin) have different microbiomes.

●The microbiome has Alpha and Beta diversity. ●Microbiome samples are compared using different axes to identify similarities and differences. ●The Human Microbiome Project classifies different organ sites, including the prostate. ●There is a link between gut inflammation and prostate cancer, suggesting that gut bacteria may influence prostate health.

“The Gut Microbiome and Cancer” (Michael Liss, MD, PhD) [#128] Impact of Diet on Microbiome and Cancer ●Research shows differences in gut microbiomes between cancer patients and healthy individuals. ●B vitamins (folate and biotin) in the gut microbiome impact cancer risk. ●Dietary changes, such as reducing sugar and carbohydrates, can affect bacterial mechanisms in the gut.

●The microbiome can be a biosensor with the potential for developing prediction models for disease types. Therapeutic Applications of Microbiome Research ●Vaccines and fecal transplants are potential treatments for cancer. ●Microbiome-based immunotherapy can enhance the body's immune response to cancer. ●Ongoing research has the potential for developing personalized microbiome-based treatments.

Challenges and Future Directions ●There are challenges of using fecal transplants and there is a need for rigorous safety measures.