Preoperative gut dysbiosis and its correlation with postoperative infectious complications and tumor recurrence in colorectal cancer patients

BACKGROUNDPostoperative infectious complications and tumor recurrence have been observed to occur at high rates in colorectal cancer (CRC).Gut dysbiosis is associated with CRC tumorigenesis and immune dysregulation but whether preoperative microbiome status independently predicts adverse surgical outcomes remains unresolved.The aim of this study was to analyze the association between preoperative gut dysbiosis and 30-day infectious complications and 2-year recurrence-free survival (RFS) in CRC patients undergoing curative resection. AIMTo determine whether the presence of preoperative gut dysbiosis in CRC patients is associated with postoperative infectious complications and tumor recurrence, and assess the potential predictive value of combining gut microbiome diversity metrics with inflammatory biomarkers for adverse postoperative outcomes. METHODSUsing a retrospective design, we enrolled 152 CRC patients, who underwent curative resection between February 2022 and April 2025.Fecal specimens collected preoperatively were sequenced using 16S rRNA gene sequencing.Based on the Shannon diversity index and Dysbiosis Index (DI), patients were stratified into the dysbiosis group (n = 94) and the normal microbiome group (n = 58).The inflammatory biomarkers measured were C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 and fecal calprotectin.The main endpoint was the 30-day postoperative infectious complication rate; the secondary endpoint was 2-year RFS.Independent predictors were identified using logistic regression and Cox proportional hazards models. / 28 RESULTSGut dysbiosis occurred in 61.8% (94/152) of patients preoperatively.The rate of infectious complications was significantly higher in the dysbiosis group (37.2% vs 17.2%, P = 0.008), as were postoperative length of stay and duration of antibiotic usage (both P < 0.001).The 2-year rate of tumor recurrence was also significantly higher in the dysbiosis group (35% vs 16.7%, P = 0.016), and the 2-year RFS rate was markedly lower (65.1% vs 84 %, Logrank P = 0.016).Multivariable analyses verified that the presence of preoperative gut dysbiosis was an independent risk factor for both infectious complications [odds ratio = 2.85, 95% confidence interval (CI): 1.32-6.15,P = 0.008] and tumor recurrence (hazard ratio = 2.42, 95%CI: 1.04-5.63,P = 0.041). CONCLUSIONOur results show that preoperative gut dysbiosis is an independent predictor of postoperative infectious complications and 2-year tumor recurrence in CRC patients.A combined biomarker model integrating the DI, CRP, and PCT achieved an area under the curve of 0.82 (sensitivity 78.0%, specificity 74.6%) for predicting postoperative infectious complications, suggesting a clinically actionable risk stratification tool.More evidence is required to incorporate gut microbiome assessment in perioperative management.