The impact of enteral immunonutrition on gut microbiota in colorectal cancer and gastric cancer patients in the preoperative period - preliminary results of randomized clinical trial

Karolina Kaźmierczak-Siedlecka^1*Ewa Stachowska²Robert Kucharski¹Piotr Wiśniewski³Paweł Ulasiński³Michal Stańczak⁴Wojciech Makarewicz³Karolina Skonieczna-Żydecka⁵Karol Połom⁶Leszek Kalinowski^1*

• ¹Department of Medical Laboratory Diagnostics – Fahrenheit Biobank BBMRI.pl, Medical University of Gdansk, Gdańsk, Poland
• ²Department of Human Nutrition and Metabolomics, Pomeranian Medical University in Szczecin, Szczecin, Poland, Szczecin, West Pomeranian, Poland
• ³Unit of Surgery with Unit of Surgery with Unit of Oncological Surgery, Specialist Hospital in Koscierzyna, Koscierzyna, Poland, Kościerzyna, Poland
• ⁴Department of Oncologic Surgery, Medical University of Gdansk, Gdansk, Poland
• ⁵Department of Biochemical Research, Pomeranian Medical University in Szczecin, Szczecin, Poland, Szczecin, West Pomeranian, Poland
• ⁶Academy of Applied Medical and Social Sciences, Elblag, Warmian-Masurian Voivodeship, Poland

Immunonutrition is a part of nutritional interventions in gastrointestinal cancer patients. It seems to be especially important in preoperative period to reduce, among others, surgery-related complications. The relation between immune system and gut microbiota has been previously analysed, however, the influence of immunonutrients on the composition of gut microbiota is still unclear. Therefore, the aim of this study was to assess the impact of enteral immunonutrition on gut microbiota in gastric/colorectal cancer patients in preoperative period.This study included 14 patients (n=9 colorectal cancer, n=5 gastric cancer) allocated to receive immunonutrition or standard products by 7 days prior to the surgery. Randomization was performed using random number generator. The stool samples were collected at day 0 and after 7 days of consuming study products. Therefore, gut microbiota analysis was conducted at the beginning and after 7 days (follow-up). The analysis consists of: alpha diversity analysis, taxonomic data processing, beta diversity analysis, differential abundance analysis.Results: Statistical analysis did not indicate any significant differences (p > 0.05) between the two dietary groups for any of the alpha diversity indices. Microbial community compositions were largely similar between the immunodiet and standard nutridrink groups. Differential abundance analysis (DAA) using the Wilcoxon test identified several taxa with nominal p-values < 0.05, suggesting potential differences in abundance between groups. However, none of these findings remained statistically significant. The taxa with nominal significance included Bilophila, CAG-56, Clostridium sensu stricto 1, Coprobacter, Holdemania, Fusicatenibacter, Ruminococcus, and [Eubacterium] eligens group.The analysis of gut microbiota in the context of immunonutrition is a new area in oncology. In the current study, despite of some initial microbial alterations, it was not finally confirmed that immunonutrition has a beneficial effect on gut microbiota in gastric and colorectal cancer patients in preoperative period, however the small sample size is one of the study's limitation.