Two recent studies have shown that patients’ gut bacteria can influence how well they respond to cancer treatments. Both studies, one from France and one from the US, collected data from patients undergoing immunotherapy, which help to combat cancer by enabling immune cells to recognise and attack tumours.
The French study involved 249 patients receiving immunotherapy for kidney, bladder or lung cancers, 69 of whom had taken antibiotics for routine infections. Antibiotics disrupt the microbiome, affecting both ‘good’ and ‘bad’ bacteria. On average, patients who took antibiotics during treatment were more likely to have relapses and did not survive as long.
The US study also compared the different gut bacteria present in 112 melanoma patients. Patients who responded well to treatment were more likely to have more diverse microbiomes and higher numbers of certain beneficial species. Patients with more of these ‘good’ bacteria were found to have more cancer-killing immune cells in their tumours.
The results from both studies hold a lot of promise. The hypothesis is that by supporting a healthy microbiome, immunotherapy is more likely to be effective at shrinking tumours.