Effect of Limosilactobacillus reuteri Probiotic on Oral Mucositis in Patients Undergoing Head and Neck Radiation: A Randomised Trial

Limited management strategies exist for cancer therapy-induced oral mucositis (OM). We conducted a randomised, double-blind, placebo-controlled trial to assess the efficacy and safety of Limosilactobacillus reuteri (LR) probiotic to prevent and reduce the severity of OM in head and neck cancer patients undergoing radiotherapy (RT). Patients ≥ 21 years requiring head and neck RT of ≥ 60 Gy and those undergoing concurrent chemotherapy with RT (CCRT) with no prior OM were recruited. OM incidence and severity were assessed weekly from baseline to two weeks post-RT. Oral samples were collected at baseline and study mid-point to profile microbiome changes. Overall, no significant differences in OM incidence or severity (grade ≥ 3) were observed between LR and placebo groups. However, subgroup analyses of participants who received RT-only showed significantly lower mean OM scores (-0.42; 95% CI: -0.75, -0.09; p = 0.02) over time in the LR probiotic group. Beta diversity of the oral microbiome was significantly different between the RT-only probiotic and placebo groups (PERMANOVA: F = 1.77; R2 = 0.07; p = 0.025). No serious adverse effects were observed in the LR group. LR probiotic use was safe and associated with a reduced OM incidence and severity in RT-only participants. These findings are promising and provide important insights for future studies in larger cohorts. ClinicalTrials.gov: NCT03552458.