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One person’s waste could be another’s shot at fighting cancer. The idea may sound far-fetched, but it is gaining momentum in cancer care. Researchers are testing fecal microbiota transplants as a way of changing the gut’s microbes. This could help treatments, such as immunotherapy, work better, and it could be especially significant for hard-to-reach cancers. These fecal microbiota could also help deliver longer-lasting benefits for more patients. Here’s what you need to know about how fecal microbiota transplants work, what cancer research has found so far, and how patients can take part as clinical trials expand.
What are fecal transplants?
As the name suggests, a fecal microbiota transplant introduces gut microbes from a carefully screened healthy donor’s stool into a patient’s gastrointestinal tract. It is most often delivered through a colonoscopy, though it can also be given through a tube passed through the nose into the stomach. More recently, some transplants have been delivered in swallowable capsules.
The idea of stool as medicine is not new. Records from fourth-century China describe “yellow soup,” a fecal mixture used to treat severe diarrhea and food poisoning, that reportedly was considered a “medical cure,” according to a 2012 letter to the editor published in the American Journal of Gastroenterology. A modern precursor entered Western medicine in 1958 when doctors used fecal enemas to successfully treat four patients with pseudomembranous colitis, a severe intestinal inflammation often linked to clostridium difficile.
Today, scientists have a clearer picture of how and why fecal microbiota transplants work. “Over the last 20 years, people began to understand the gut microbiome seems to be involved in so many different things, the two major ones are your immune system and metabolism,” said Dr. Andrew Koh, a pediatric hematologist-oncologist at UT Southwestern Medical Center, who studies the gut microbiome.
Gut microbes help train the immune system to recognize and respond quickly to real threats, such as pathogens or cancerous cells, Koh said. At the same time, they help keep that response in check, reducing the risk the immune system overreacts to harmless microbes or the body’s own tissues in ways that can fuel autoimmune diseases.
How are fecal transplants helping with cancer?
Since a landmark 2013 study showed fecal microbiota transplants were highly effective for patients with recurrent C. diff infections, the Food and Drug Administration has since approved the treatment for that use. (The bacterial infection causes nearly half a million illnesses in the United States and an estimated 29,300 deaths each year, according to the Centers for Disease Control and Prevention.
In cancer care, fecal microbiota transplants are being used to treat some patients who develop gastrointestinal side effects from immunotherapy, said Dr. Jennifer Wargo, a surgical oncologist at the University of Texas M.D. Anderson Cancer Center. But researchers like Wargo are studying whether the procedure can boost the effectiveness of immunotherapies, which help the body’s immune system find and kill cancer cells.
Over the past several years, studies have suggested some people with cancer have less diverse, less balanced communities of gut microbes, Wargo said. This disruption, often called dysbiosis, can happen for many reasons, including diet, antibiotic use, and even physical activity levels. But research so far suggests restoring the microbiome through a fecal microbiota transplant may improve how well some patients respond to immunotherapy and, in turn, their longer-term outcomes.
In a 2021 study, Wargo and her colleagues performed fecal microbiota transplants in 10 people with advanced melanoma whose cancers had stopped responding to immunotherapy. Three patients responded: Two had partial responses, meaning their tumors shrank, and one had a complete response, with no detectable cancer after treatment.
More recently, a Canadian study reported that giving fecal microbiota transplants before patients started immunotherapy for lung cancer or melanoma was linked to higher response rates. In that trial, 75% of patients with melanoma who received a transplant responded to treatment, compared with the roughly 50% to 58% response rates typically seen with immunotherapy alone.
How can you or a loved one get involved?
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Fecal microbiota transplants are being studied at a time when cancer remains widespread in the US and in Texas. More than 148,000 new cancer cases were expected to be diagnosed in 2025 in the Lone Star State, including over 72,000 cancers in women and more than 76,000 cancers in men, according to the Texas Department of State Health Services.
For patients interested in fecal microbiota transplants, Koh and Wargo recommend talking to your oncologist. Additionally, you can search Clinicaltrials.gov to see which studies are recruiting in Texas.
There are risks to transplanting another person’s stool, including a small but real chance of transferring harmful pathogens. Wargo cautioned against attempting a do-it-yourself transplant.
“With cancer patients, we’re concerned about safety,” she said. “We don’t want people to be doing their own poop transplant. They need to work with their treatment teams, first and foremost.”
-by Miriam Fauzia, a science reporting fellow at The Dallas Morning News. Her fellowship is supported by the University of Texas at Dallas. The News makes all editorial decisions.
©2026 The Dallas Morning News. Visit dallasnews.com. Distributed by Tribune Content Agency, LLC.
Published February 12, 2026