Changes of Intestinal Microbiota in Ovarian Cancer Patients Treated with Surgery and Chemotherapy.

Purpose: Ovarian cancer is the leading cause of death in gynecologic malignancies. Growing evidences demonstrate that a complicated relationship exists between the gut microbiota and cancer treatment. However, there are few studies explored the alterations of gut microbiota in ovarian cancer patients following anti-cancer treatments. Therefore, we aim to analyze the changes of the gut microbiota in ovarian cancer patients treated with radical surgery and chemotherapy. Patients and Methods: The microbial genes were examined from a total of 75 fecal samples from 18 ovarian cancer patients, including 10 preoperative fecal samples (Group B), 4 postoperative fecal samples (Group M0), as well as 61 fecal samples after first to fifth cycles of chemotherapy, using 16S rRNA sequencing. Results: Our results showed that fecal samples collected in postoperative (Group MO) exhibited significant decreases in abundance of Bacteroidetes and Firmicutes, while a significant increase in abundance of Proteobacteria compared with preoperative (Group B) fecal samples. LEISe analysis identified that Bilophila and Faecalibacterium are the key genera in Group B, while Klebsiella and Enterococcus are the key genus in Group MO. Compared with before chemotherapy, the abundance of Bacteroidetes and Firmicutes increased, and the abundance of Proteobacteria decreased after chemotherapy. In addition, anaerobic bacteria, such as Bacteroides, Collinsella and Blautia, exhibited significant increases after chemotherapy. Moreover, we observed that certain bacterial genera were significantly correlated with clinicopathological characteristics of ovarian cancer patients. Conclusion: Our study suggested that radical surgery and chemotherapy altered the composition of gut microbiota in ovarian cancer patients. Therapeutic strategies targeting the gut microbiota may be beneficial for the clinical treatment of ovarian cancer.