To explore the relationship between postoperative intestinal flora and depression in patients with rectal cancer.

Fifty-seven patients with depression after radical resection of rectal cancer from January 2022 to August 2023 were selected as the observation group, and 43 patients without depression after radical resection of rectal cancer during the same period were selected as the control group. SPSS 22.0 software was used to complete data analysis. The equal measurement data of intestinal flora abundance in the two groups were represented by () and independent t test was performed. The equal measurement data of intestinal flora disturbance ratio between the two groups were compared by [cases (%)], and χ² test was performed. Logistic multivariate analysis of the risk factors of postoperative depression in rectal cancer; The relationship between intestinal flora and Hamilton Depression Scale (HAMD) score was analyzed by Pearson correlation. P<0.05 was statistically significant.

The proportion of insomnia, the levels of interleukin-6 (IL-6) and C-reactive protein (CRP) in observation group were significantly higher than those in control group (P<0.05). The proportion of flora disorder Ⅰ, abundance of firmicutes, Chao1 index and Shannon index in observation group were significantly lower than those in control group, while the abundance of Bacteroidetes, Proteobacteria and actinobacteria and the proportion of flora disorder Ⅱ were significantly higher than those in control group, with statistical significance (P<0.05). Multivariate Logistic regression analysis showed that insomnia, degree Ⅱ of intestinal flora imbalance, decreased abundance of firmicutes, increased abundance of Bacteroidetes, increased abundance of Proteobacteria, increased abundance of actinobacteria, and decreased Chao1 index and Shannon index were independent risk factors for postoperative depression in rectal cancer patients (P<0.05). Pearson correlation analysis showed that HAMD score was significantly positively correlated with Bacteroidetes, Proteobacteria and actinobacteria (P<0.05), and significantly negatively correlated with Firmicutes, Chao1 index and Shannon index (P<0.05).

The increased abundance of Bacteroides, Proteobacteria and actinomycetes, the decreased abundance of firmicutes and the decreased richness and diversity of intestinal flora in postoperative patients with rectal cancer are related to the occurrence of depression, and are independent risk factors affecting the occurrence of depression.