Effectiveness of Streptococcus salivarius probiotics on alleviating radiation-induced oral mucositis via inflammatory and microecological modulation: a prospective pragmatic interventional study in nasopharyngeal carcinoma.

Oral mucositis was nearly universal in nasopharyngeal carcinoma patients receiving chemoradiotherapy, with severe cases occurring in nearly half.

• Among 69 evaluable patients, OM occurred in 95.7% of patients.
• Severe OM (SOM) was observed in 42.4% of patients.
• Patients were grouped by probiotic exposure: no probiotic, Streptococcus salivarius K12 (SsK12), or Streptococcus salivarius M18 (SsM18).
• Weekly oral assessments were used to characterize the onset, duration, and severity of OM.

SsM18 supplementation significantly delayed OM onset, reduced severe OM duration, and shortened total OM duration compared with the non-probiotic group.

• SsM18 significantly delayed OM onset compared with the non-probiotic group (p = 0.014).
• SsM18 reduced severe OM (SOM) duration (p = 0.019).
• SsM18 shortened total OM duration (p = 0.031).
• SsM18 outperformed SsK12 on these OM-related outcomes.
• The study design was a prospective pragmatic interventional study.

Group-based trajectory modeling identified two distinct OM trajectory groups among NPC patients undergoing chemoradiotherapy.

• GBTM identified a 'Rapid-Onset, Severe' trajectory group and a 'Late-Onset, Mild' trajectory group.
• These two trajectories reflect the marked heterogeneity in OM severity and onset timing noted among patients.
• GBTM (group-based trajectory modeling) was applied to weekly oral assessment data to derive these trajectories.

Elevated IL-6 levels and high Beck Oral Assessment Scale score were identified as independent predictors of the 'Rapid-Onset, Severe' OM trajectory.

• Elevated log-transformed Interleukin-6 levels were an independent predictor of the 'Rapid-Onset, Severe' trajectory (OR = 4.20, p = 0.020).
• High Beck Oral Assessment Scale (BOAS) score was also an independent predictor of the 'Rapid-Onset, Severe' trajectory (OR = 3.06, p = 0.044).
• These associations were identified through multivariate analysis.

The Teeth subdomain of the Beck Oral Assessment Scale was an independent predictor of earlier OM onset.

• The Teeth subdomain of BOAS was identified as an independent predictor for earlier OM onset (p = 0.042).
• This finding was derived from multivariate analysis.
• The result suggests that baseline dental health status influences the timing of OM development.

The association between a higher Teeth subdomain score and OM was partially mediated by IL-6 elevation.

• Mediation analysis suggested that IL-6 elevation partially mediated the relationship between higher Teeth subdomain score and OM.
• The proportion mediated by IL-6 was estimated at 30–50%.
• This indicates that baseline oral health influences OM at least partly through an inflammatory mechanism.

Pre-existing oral microbiome and host inflammatory tone were identified as contributors to inter-patient heterogeneity in radiation-induced oral mucositis severity.

• The study was motivated by evidence that heterogeneity in OM severity 'is influenced by the pre-existing oral microbiome and host inflammatory tone.'
• Baseline oral health (assessed via BOAS) and inflammatory status (IL-6) were both associated with OM trajectories.
• The study population consisted of NPC patients receiving chemoradiotherapy.