The Chemo-Gut Probiotic Trial Protocol: A Double-Blind Randomized Controlled Trial Investigating the Effects of a Multi-Strain Probiotic on Gut Microbiota, Gastrointestinal Symptoms, and Psychosocial Health Among Cancer Survivors

Background: Survivors of cancer experience chronic gastrointestinal (GI) and psychosocial health symptoms and reduced gut microbial diversity. This may compromise their long-term health and wellbeing. No studies have investigated probiotics for managing both GI and psychosocial symptoms together, or their effects on the composition of the gut microbiota in post-treatment cancer survivors. Aims: To investigate the effects of a probiotic vs. placebo on (i) abdominal pain and depressive symptoms (primary outcomes); (ii) (a) GI (i.e., gas/bloating, diarrhea, and constipation), and psychosocial (i.e., anxiety, cognitive function, and fatigue) symptoms and (b) gut microbiota composition; and (iii) relationships between bacteria and GI and psychosocial symptoms. Methods: This double-blind, placebo-controlled, two-arm, randomized trial will recruit N = 66 participants allocated 1:1 to the probiotic or placebo group for a 12-week trial. Adult survivors diagnosed with a solid tumor or blood cancer who have completed chemotherapy within the last 5 years and show elevated GI or psychosocial symptoms will be included. The probiotic capsule contains a blend of Lacticaseibacillus rhamnosus, Lactobacillus helveticus, and Bifidobacterium animalis subsp. lactis strains, ingested orally once daily. Stool samples will be collected at baseline and week 12 and analyzed using 16S rRNA gene sequencing. GI and psychosocial surveys will be completed at baseline and at weeks 6 and 12. Descriptive statistics, frequencies, paired-samples t-tests, linear mixed models, and Spearman’s correlational analyses will be used. Conclusions: We explore a novel, microbiota-based intervention for chronic GI and psychosocial symptoms following cancer treatment. Our findings and commitment to person-centered knowledge translation via creating informational materials will enable people to make informed decisions about their health.