Decrease of oral microbial diversity might correlate with radiation esophagitis in patients with esophageal cancer undergoing chemoradiation: A pilot study

Abstract

Abstract Objective Radiation esophagitis (RE) is a common treatment‐emergent adverse event that leads to significant morbidity and mortality in patients with unresectable esophageal cancer undergoing chemoradiotherapy. In the present study, we aimed to investigate the correlation between oral bacterial diversity and RE in patients with esophageal cancer undergoing chemoradiotherapy. Methods This study included 21 patients undergoing chemoradiotherapy, and 10 patients undergoing chemotherapy for pathologically confirmed squamous cell esophageal cancer between July 2018 and February 2019 at Shandong Cancer Hospital. Oral mucosal swabs were collected from 10 patients without RE, 11 patients with grade 1 RE, and 10 patients with grade ≥2 RE. The RE grade was based on the Common Terminology Criteria for Adverse Events (v5.0). Oral bacterial diversity was assessed by 16S rRNA gene sequencing. Permutational multivariate analysis of variance was carried out to determine whether the overall bacterial community composition differed among the groups. Linear discriminant analysis effect size was used to analyze species with significant differences among groups. Metagenome content was predicted using phylogenetic investigation of communities by reconstruction of unobserved states. Results The overall bacterial community composition was similar among the three groups. The abundance of the phylum Bacteroidetes was decreased in patients with RE compared with those without RE (linear discriminant analysis value >4, P < 0.05). There were significant functional differences in the flora between the patients without RE and patients with grade 1 RE, as well as between the patients without RE and patients with grade ≥2 RE (P < 0.05). Conclusion A decrease in oral bacterial diversity might be correlated with RE in patients with esophageal cancer undergoing chemoradiotherapy. These findings warrant further studies for the verification and elucidation of the underlying mechanisms, which will provide a theoretical basis for the prevention and treatment of RE.

Keywords

• 16S rRNA gene sequencing
• oral microbiota
• radiation esophagitis
• squamous cell esophageal cancer