Impact of the oral microbial profile on the risk of treatment-related oral toxicities in patients with head and neck cancer before the 16S rRNA gene amplification sequencing technology era: A systematic review and a meta-analysis

This review and meta-analysis aim to identify studies that characterized changes in the oral microbial profile and link these changes to the risk of oral toxicities during and after HNC treatment. We searched PubMed, Ovid MEDLINE, and Ovid EMBASE databases. The primary outcome was oral toxicities. Odds ratio (OR) with 95% confidence interval (95%CI) was estimated. Meta-regression and leave-one-out sensitivity analyses were performed. We found 2765 articles, of which 13, with a total of 717 patients were eligible. Across studies, the oral microbial profile varied during treatment courses, and this diversity was associated with the timing and progression of the oral toxicities. Increased abundance of gram-negative bacteria at baseline and over time seemed to increase the risk of mucositis. The risks of oral toxicities and severe mucositis were lower after restoring the oral microbiota balance ((OR 0.32 (95% CI 0.12–0.83) and OR 0.37 (95% CI 0.16–0.85), respectively), and independent of age and gender. Use of narrow-spectrum antibiotics reduced the risk of severe mucositis (OR 0.19 (95% CI 0.05–0.68)). We concluded that monitoring the changes in oral microbial profile may identify high-risk patients and modifying oral microbial profile may reduce the risk of severe mucositis during and after HNC treatment.