Alteration of intestinal flora after radiotherapy in patients with pelvic cancer

Objective To investigate the effect of pelvic radiotherapy on intestinal flora, the correlation between radiation enteritis and intestinal flora, and the effect of probiotics intervention on intestinal flora and diarrhea. Methods From March to November 2018, a total of 22 patients who were admitted to the Affiliated Suzhou Hospital of Nanjing Medical University were enrolled in the study, including 5 patients with colorectal cancer, 15 patients with cervical cancer and 2 patients with endometrial carcinoma. Five patients with cervical cancer received oral administration of probiotics combined with radiotherapy. Ten healthy physical examiners were selected as the control group. The stool samples were collected from each patient before and after radiotherapy, and 16S rDNA sequencing technology was used to detect the fecal flora and analyze the effect of radiotherapy on intestinal flora. Results The main composition of intestinal flora in the stool samples of healthy control group was Firmicutes (39.86%), Bacteroidetes (37.77%), unclassified bacteria (15.96%) and Proteobacteria (5.03%), which was similar to patients, but the abundance of bacteria was significantly different. There were differences in the intestinal flora of patients before and after radiotherapy. Microbial diversity and abundance were altered after radiotherapy, especially in patients who later developed severe diarrhea. The Firmicutes/Bacteroidetes ratio was altered after radiotherapy. The abundance of Escherichia-Shigella and Fusobacterium increased after radiotherapy in patients who developed severe diarrhea. Oral administration of probiotics could alleviate the diarrhea and reduce the decline of microbial diversity and abundance. Conclusions In patients with pelvic tumors, the diversity and abundance of intestinal flora decrease after radiotherapy, especially in patients with severe diarrhea. Oral probiotics can alleviate the diarrhea. Key words: Pelvic neoplasms; Radiation enteritis; 16S rDNA; Intestinal flora; Probiotics