Homeostatic Balance of Gut Microbiota in Head and Neck Squamous Cell Carcinoma Patients during Radiotherapy.

Abstract

Radiotherapy is the major treatment for head and neck squamous cell carcinoma (HNSCC). Oral microbiota changes have been described before. However, gut microbiota changes in HNSCC patients who received local radiotherapy remain unclear. We aim to investigate the dynamic change of gut microbiota composition in HNSCC patients undergoing radiotherapy and to construct the radiotherapy related gut microbiota database in HNSCC patients. We enrolled 47 HNSCC patients who scheduled with radiotherapy solely. Intensity-modulated radiotherapy (IMRT) was the standard radiotherapy technique for all the enrolled patients. The field was irradiated with a total dose of 60-66Gy in 30-33 fractions. Fecal pellets were collected at three time points. Bacterial genomic DNA was isolated using magnetic beads and then analyzed by the Illumina MiSeq Sequencing System based on the V3-V4 hypervariable regions of the 16S rRNA gene. A total of 194 genera which belonged to 27 phyla were found in 141 samples. Increased abundance of microbiota in diversity and richness was observed in mid-radiotherapy group. Moreover, Bacteroides, Blautia, and Phascolarctobacterium were three main genera in all three groups and the mid-radiotherapy group had the highest relative abundance of Phascolarctobacterium. What's more, most significantly altered bacteria shared the same variation pattern which was increased in mid-radiotherapy while decreased to the almost same level of as pre-radiotherapy in post-radiotherapy group. Local radiotherapy can affect the composition of the gut microbiota in HNSCC patients during the mid-term of radiotherapy. However, self-stabilized ability maintained the gut microbiota homeostasis in the end.