The specific mix of bacteria in a person's gut can predict the chances that melanoma will return after surgery and immunotherapy, according to a study led by researchers from NYU Langone Health and its Perlmutter Cancer Center, published on April 17.
This finding is important because it could help doctors identify which patients are more likely to see their cancer come back, allowing for more personalized care. Melanoma recurrence remains a challenge, with previous studies showing that between 25 and 40 percent of patients experience a return of the disease despite standard treatments.
Researchers analyzed stool samples from 674 patients who participated in an international clinical trial called CheckMate 915. These patients had undergone surgery to remove their tumors and then received either a combination of immunotherapies or one type alone. The study found that differences in certain bacterial groups—Eubacterium, Ruminococcus, Firmicutes, and Clostridium—could predict cancer recurrence with up to 94 percent accuracy when analyzed using new methods. The team also discovered that these bacterial markers varied depending on where the patient lived but could still be used as reliable predictors if grouped by overall similarity in microbiome makeup rather than geography.
"Past studies have struggled because the gut bacteria that predict treatment success seemed to change from one region to another," said Dr. Ahn. "Our study provides a new method that overcomes this barrier, showing that these markers are indeed generalizable if we account for the person's underlying microbiome."
The research also showed that the gut microbiome remained stable during a yearlong course of immunotherapy. "This means that a single pretreatment microbiome test could provide a reliable forecast of a patient's risk," said Richard B. Hayes, DDS, PhD, MPH, professor in the Department of Population Health at NYU Langone Health. "The next step is to validate this matching approach in other cancers and to build the diverse databases needed to make this approach clinically feasible. In the future, we envision analyzing a patient's microbiome before treatment, comparing it to a global database, and providing a reliable prognosis that guides therapy from the start."
