Abstract

Objective: To evaluate the effect of a probiotic combination on clinical and oral microbiological parameters in patients with head and neck cancer (HNC) undergoing radiotherapy. Materials and Methods: A randomised, double-blind, placebo-controlled clinical trial was conducted with 72 HNC patients who had received radiotherapy within the past year. Participants were randomly assigned to receive either daily probiotic sachets or placebo for 30 days. Salivary parameters—including unstimulated and stimulated flow rates and pH—were evaluated alongside oral microbiota profiles, including total bacterial load and selected periodontopathogens. Assessments were performed at baseline and post-intervention using sialometry, pH analysis, bacterial culture, and quantitative real-time PCR (qPCR). Results: Sixty-one patients completed the study (31 in the probiotic group, 30 in the placebo group). Stimulated salivary flow increased significantly in the probiotic group (p = 0.0016), while unstimulated flow improved in both groups (p < 0.05). Salivary pH decreased significantly in the probiotic group (p = 0.0209); however, no intergroup differences were observed at the end of the intervention (p = 0.9839). qPCR showed significant reductions in total bacterial load (p = 0.0209) and Fusobacterium nucleatum (p = 0.0080). Culture confirmed the reduction of F. nucleatum (p = 0.0026), with a trend towards significance for total cultivable bacterial count (p = 0.0502). Conclusions: Daily supplementation with a probiotic combination may serve as a practical and well-tolerated adjunctive measure in clinical settings to improve salivary function and reduce key oral pathogens, particularly Fusobacterium nucleatum, in patients undergoing or recovering from radiotherapy for head and neck cancer. These findings support its potential integration into routine supportive care protocols to mitigate xerostomia and oral dysbiosis in this population. © 2025 by the authors.