Abstract 5123: Changes of oral microbiome profiles associated with oral squamous cell carcinoma

Abstract

Abstract [Background] Oral squamous cell carcinoma (OSCC) is the most frequently occurring cancer among the head and neck SCCs worldwide. Despite significant efforts in OSCC research and advanced surgical treatments, radiotherapy, and chemotherapy, the 5-year overall survival rate has remained < 50% for the last few decades. OSCC prognosis remains poor due to late diagnosis. Therefore, clinically effective biomarkers for the early detection of OSCC can greatly improve the survival rate and prognosis. Approximately 15% of oral cancers cannot be explained by major risk factors, such as tobacco and alcohol use. A growing body of evidence supports an association between specific microorganisms, including those in the oral cavity, and various types of cancers. Because the role of bacteria in OSCC development has not been completely described, we investigated the changes in abundance of oral microbiota associated with OSCC. [AIMS] To identify the association between the oral microbiome and OSCC for the early detection and prevention. [Materials and methods] Unstimulated saliva samples were collected from 4 OSCC-free, 6 leukoplakia, and 6 OSCC subjects. Total bacterial genomic DNA from saliva was isolated, and 16S rRNA gene survey was performed by next-generation sequencing of the V4 region. The sequences were analyzed against reference sequences from the Human Oral Microbiome Database, and the relative abundance distribution for phylogenetic groups in 3 different libraries was compared. [Results] In total, 448 bacterial species from combined (OSCC-free, leukoplakia, and OSCC) libraries were detected, which were classified into 133 genera, 69 families, 41 orders, 26 classes, and 12 phyla. The frequency of phylum Bacteroidetes was more notably abundant in OSCC subjects compared with leukoplakia and OSCC-free subjects. In contrast, the abundances of genera Streptococcus and Rothia were significantly lower in OSCC subjects compared with leukoplakia and OSCC-free subjects using the Mann-Whitney U test. [Conclusion] This study revealed some OSCC-associated shifts in oral microbial communities. Salivary screening is suitable for the primary screening procedure because of its noninvasiveness and easy accessibility. Therefore, these changes in the saliva microbiome may have potential application as a useful diagnostic tool for the early detection of OSCC and malignant transformation of pre-cancerous regions. Citation Format: Kengo Hashimoto, Shuji Nomoto, Sho Hirabayashi, Sei Ueda, Ichiro Oh-iwa, Toru Nagao, Kazuo Shimozato. Changes of oral microbiome profiles associated with oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5123.