3643 - Evaluation of Oral Microbial Alpha Diversity and Systemic Inflammatory Response during Radiotherapy for Head and Neck Cancer
Presenter(s)
A. Ue1, Y. Tamaki1, K. Nonomura1, U. Yamamori1, H. Burioka2, N. Nagano1, M. Uno1, Y. Sonoyama1, R. Morioka3, H. Usuda3, T. Okamoto3, and K. Wada3; 1Department of Radiation Oncology, Shimane University, Izumo, Japan, 2Department of Radiation Oncology, Shimane Prefectural Central Hospital, Izumo, Japan, 3Department of Pharmacology, Shimane University, Izumo, Japan
Purpose/Objective(s): Systemic inflammatory markers have been reported to be associated with prognosis in head and neck cancer. This study aimed to evaluate the association between oral microbial alpha diversity and systemic inflammatory response during radiotherapy.
Materials/Methods: This study was a retrospective secondary analysis of a prospectively collected cohort of patients receiving radiotherapy for head and neck cancer. Oral samples were collected before, during, and after radiotherapy. Alpha diversity was assessed using the Chao1 and Shannon indices based on 16S rRNA sequencing data. Systemic inflammatory markers, including C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR), were measured at corresponding time points. Associations between alpha diversity and inflammatory markers were evaluated using univariate linear regression and multivariable models adjusting for total radiation dose, chemotherapy, antibiotic use, and maximum mucositis grade.
Results: A total of 43 patients were included. Following the initiation of radiotherapy, both CRP and NLR increased significantly (comparison between before and after treatment, p<0.05). The Chao1 index also showed a significant increase from before to after treatment, whereas the Shannon index did not demonstrate significant changes throughout the treatment course. In univariate analyses, baseline Chao1 was positively correlated with NLR after treatment and with the change in NLR from before to after treatment (p<0.01). Similarly, baseline Chao1 was significantly associated with CRP after treatment and with the change in CRP from before to after treatment (p<0.01). In multivariable analyses, baseline Chao1 remained significantly associated with CRP after treatment, NLR after treatment, and their respective changes from before to after treatment (p<0.01).
Conclusion: Baseline oral microbial richness was significantly associated with systemic inflammatory response during radiotherapy after adjustment for treatment-related factors. These findings suggest that oral microbial alpha diversity may have potential as a biomarker for treatment-related inflammation in head and neck cancer.