Probiotics, traditionally perceived to be good for the gut and overall health, may not be the best choice in patients with cancer. The surprising preliminary findings of a recent study in patients with melanoma indicate that users of over-the counter (OTC) probiotics have one-third the odds of responding to immunotherapy treatment with anti-programmed cell death-1 checkpoint inhibitors compared with patients not taking probiotics.
"What we found is that patients who are taking probiotics have decreased diversity of the microbiome, a key measure of overall gut health, and seem to have a decreased response to immunotherapy," said Jennifer McQuade, MD, MS, MA, LAc, medical oncologist with the University of Texas MD Anderson Cancer Center in Houston.
While such a dramatic decrease in the efficacy of immunotherapy in probiotic users may come as a surprise, a close link between the gut microbiome composition and the efficacy of cancer therapies has already been established in numerous human and animal studies. Microbiome patterns associated with improved response to cancer immunotherapies have been identified, prompting researchers to more closely examine the microbiome signatures of individuals who responded to treatment.
As the science on this topic continues to emerge, both clinicians and patients are left wondering whether interventions into the microbiome can increase the chances of a positive outcome.
