Abstract 3040: A modified microbiota-accessible carbohydrates diet could change gut microbiota in patients with colorectal cancer after surgery
Authors: Kim Boyeon , Lee Jiwon , Kim Jin , Kwak Jung-Myun , Cho Hye-Jin , Jung Eun Sung , Lee Sunyoung , Suh Dong Ho , Park Yu Jin , Lee Soohyeon 
Published: April 2023

Abstract
Dietary factors have important role in modulating the gut microbiome, which in-turn regulates the molecular events in colonic mucosa. The composition and resulting metabolism of the gut microbiome are decisive factors in colorectal cancer (CRC) tumorigenesis. Microbiota-Accessible Carbohydrates (MAC) refer to carbohydrates that the human intestine cannot digest, but that can be digested by intestinal microbes. During that process, short chain fatty acid (SCFA) is produced, which is known to increase beneficial intestinal bacteria and decrease inflammation around intestinal cells. This prospective, longitudinal study aims to explore the changes in the composition and diversity of intestinal microbiota according to the diet pattern in patients with stage I to lll CRC. Participants were assigned to 3-week modified MAC diet group or free diet group followed by diet switching for 3 weeks. Modified MAC diet was designed to adapt to a high fiber diet including 30g of dietary fiber daily and delivered to the patient’s home for 3 weeks as a meal kit supported by Dr. Kitchen Corp. We collected 113 fecal samples from 40 CRC patients before and after diet switching. To explore the effect of diet on the composition of the microbiota and pattern of defecation, 16S rRNA sequencing were performed using fecal samples. Biological information was processed by Qiime2 plugins, DESeq2 and Lefse. Among total 40 participants, 26 (65%) were male. There were 11 (27.5%) with right colon cancer and 29 patients with left colon and rectal cancer. 18 patients without adjuvant chemotherapy were lower stage and higher compliance to modified MAC diet (median 89%) than 22 patients with adjuvant chemotherapy (median 60%). In all participants, protein and dietary fiber intake increased by more than 90% and sodium intake decreased by more than half during modified MAC diet compared to the free diet. There was no difference in alpha diversity change between chemotherapy group and non-chemotherapy group but a significant difference was observed in beta diversity change. Especially, Lachnospiraceae Eubacterium hallii were enriched in non-chemotherapy group. During the modified MAC diet in the group not receiving chemotherapy, Lactobacillaceae Pediococcus, Prevotellaceae Prevotella, Streptococcaceae Lactococcus were increased and Ruminococcaceae Eubacterium siraeum group, Ruminococcaceae UBA1819 were decreased. This study results showed that 3 weeks dietary intake influences the structure and activity of gut microbiome even though the dietary responsiveness of the individual’s microbiota varied substantially. The joint study of microbiome and metabolome has been ongoing now as the most promising approach to evaluate host-microbiome interaction. In order to prove the importance of a balanced diet after colorectal cancer surgery, it will be necessary to analyze the relationship with clinical outcomes.
Citation Format: Boyeon Kim, Jiwon Lee, Jin Kim, Jung-Myun Kwak, Hye-Jin Cho, Eun Sung Jung, Sunyoung Lee, Dong Ho Suh, Yu Jin Park, Soohyeon Lee. A modified microbiota-accessible carbohydrates diet could change gut microbiota in patients with colorectal cancer after surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3040.