Study links healthy gut to improved cancer survival
The human digestive system it turns out is not all human.
It also depends on numerous types of friendly foreign bacteria to help break down the food we eat into microscopic fuel molecules that are absorbed into the walls of the small intestines. From there, they are whisked away into the bloodstream to wherever our bodies need them most.
Trillions of foreign microbes work within our bodies to help form the gut microbiome. Without them, we would starve. So, it only makes sense that a healthy gut microbiome plays a critical role in our overall health.
But what makes a healthy gut microbiome? And what effect does it have in cancer treatment?
Scientists and physicians at TGen and City of Hope recently found that, at least in patients with metastatic kidney cancer, a higher diversity of microbes in the gut is associated with better cancer treatment outcomes.
Their published findings, entitled — Stool Microbiome Profiling of Patients with Metastatic Renal Cell Carcinoma Receiving Anti-PD-1 Immune Checkpoint Inhibitors —appeared recently in the scientific journal European Urology.
Studying samples collected from 31 individuals with metastatic kidney cancer (meaning the cancer had spread to other parts of the body), researchers for the first time sequenced microbes in the gut microbiome at three points in time: before therapy, and again four- and 12-weeks after the start of therapy.
All patients received an immunotherapy regimen to fight their cancer; some also received a probiotic supplement.
“The patients with the highest benefit from cancer treatment were those with more microbial diversity, but also those with a higher abundance of a specific bacterium known as Akkermansia muciniphila,” said Sarah Highlander PhD, a research professor in TGen’s Pathogen and Microbiome Division, and one of the study’s senior authors. “This organism has been associated with benefit in other immunotherapy studies.”
Highlander said one potential takeaway from the study is that oncologists might encourage patients to pay attention to their gut microbiome by eating a high-fiber diet, including fruits and vegetables high in fructo-oligosaccharides (a small dietary fiber) such as bananas, dried fruit, onions, leeks, garlic, asparagus and artichokes, as well as grains with resistant starches such as barley or uncooked potato starch.
“We also reported the changes over time in the gut microbiome that occur during the course of therapy. The cumulative findings from our report open the door to therapies directed at the microbiome,” said Sumanta Pal, MD, one of the study’s senior authors and co-director of the Kidney Cancer Program at City of Hope.
It has only been in recent years that researchers have acknowledged the importance of the gut microbiome to general health, its role in disease states, and how microbes might interact with treatments. There still is so much more to be learned, including the role of the gut microbiome in fighting off infections.
Highlander suggested that next steps for researchers should include expanding their relatively small study to a much larger group of patients that are followed over a longer time period.
City of Hope researchers have embarked on a clinical trial to further explore the idea that modulating the gut microbiome during cancer therapy could have a positive impact on clinical outcomes.
Collaborations between investigators at TGen and clinicians at City of Hope have contributed to advancements in the understanding of not just the microbiome, but also in cancer biology and clinical outcomes at large.
“This current study is a further testament to the collaborative research structure we’ve developed between the affiliate institutions,” said Dr. Pal, who is an internationally recognized leader in the area of genitourinary cancers. “Through these collaborations we can implement both a bench-to-bedside and bedside-to-bench research model that will
lead to better patient care at City of Hope through access to clinical trials and precision medicine approaches."