Levels of systemic inflammation response index are correlated with tumor-associated bacteria in colorectal cancer

The relationship between systemic inflammation and tumor-associated bacteria is largely unknown in colorectal cancer (CRC). The primary aim of this study was to investigate the prognostic effects of the systemic inflammation response index (SIRI) on the survival outcomes of CRC patients who experienced surgical therapy, and the second aim was to reveal the potential association between SIRI levels and tumor-associated bacteria in CRC. We recruited a cohort of 298 CRC patients who experienced surgical resection in Wuhan Union Hospital. These patients were assigned to the low and high groups based on the cut-off value of SIRI. We utilized 1:1 propensity score matching (PSM) to reduce the potential confounding factors between the low SIRI group (N = 83) and the high SIRI group (N = 83). The total DNA of 166 paraffin-embedded tumor tissues and 24 frozen tumor tissues was extracted and amplified, and 16 S rRNA sequencing was employed to uncover the composition of microbiota between low and high SIRI groups. Survival analysis uncovered that the high SIRI cohort exhibited significantly shorter overall and disease-free survival time than low SIRI companions after PSM. The ROC analyses showed that the prediction abilities of SIRI were much higher than other serum inflammatory biomarkers for survival outcomes. The microbial richness and diversity in the low SIRI group were remarkably higher than those in the high SIRI group. At the phylum level, we found that Proteobacteria, Synergistetes, WPS-2, Thermil, Fusobacteria were enriched in the high SIRI group. Cupriavidus, Thermus, Ochrobactrum, Cupriavidus, Acidovorax were enriched in the high SIRI group at the genus level. 16 S rRNA based on frozen samples also obtained similar results. SIRI is a promising and novel prognostic biomarker among CRC sufferers who underwent surgical removal. There existed significant differences in the diversity and compositions of tumor-associated bacteria between the low and high SIRI groups.