Gut microbiome signature predicts melanoma recurrence with 94% accuracy

Researchers at NYU Langone Health's Perlmutter Cancer Center have identified a gut bacteria signature that predicts the return of skin cancer following surgery and immunotherapy with up to 94% accuracy. The findings, published in the journal Cell in April 2026, are based on a global clinical trial involving 674 patients.

Specific bacterial groups—including Eubacterium, Ruminococcus, Firmicutes, and Clostridium—were directly linked to the risk of cancer relapse. These microbes play a role in training the immune system within the digestive tract to distinguish harmful from beneficial agents, and they also influence the sugar supply that feeds cancer cells, thereby altering the body's response to immunotherapy.

Geography shapes the bacterial fingerprint

The study revealed that a patient's geographic location significantly shapes their bacterial "fingerprint," with the types of bacteria that drive immune responses differing between residents of North America, Europe, and Australia. To overcome this challenge, the research team classified patients based on overall similarities in their gut microbes, allowing indicators from one region to successfully predict outcomes for patients in other regions as long as their bacterial signatures matched.

Gut bacterial communities remained remarkably stable throughout a full year of immunotherapy treatment, according to the site TN. This stability opens the door to a single pre-treatment test that can provide reliable predictions about the future course of the disease, helping doctors design personalized treatment plans for each patient rather than relying on general forecasts.