ABSTRACT
Objective:To explore the differences in bacterial community structure between proximal colon cancer (PC), distal colon cancer (DC), and rectal cancer (RC), and the values of featured microbiota in differentiating PC with tumor markers.Methods:This case-control study enrolled 85 newly diagnosed colorectal cancer patients, including 22 PC, 15 DC and 48 RC patients, and 8 colorectal adenoma patients from May 2019 to July 2022 at the Department of General Surgery, Anyang Oncology Hospital. The blood and fecal samples were collected before surgery and then subjected to biochemical tests for tumor markers and 16S rDNA tests, respectively. SPSS (27.0.1) was applied to perform the t-test, one-way ANOVA, Mann-Whitney U test, Kruskal-Wallis H test, and Chi-Squared Test. Also, the receiver operating characteristic curve (ROC) was plotted on tumor markers and/or f_Bacteroidaceae with SPSS software .Results:All groups had significant differences in the CA125 ( F=3.543, P<0.05), CA72-4 ( F=3.596, P<0.05), and serum tumor-associated materials (TAM) levels ( F=5.787, P<0.01). In PC group, the levels of CA125 [PC vs RC, (36.84±6.30) kU/L vs (12.73±4.21) kU/L, P<0.01] and CA72-4 [PC vs RC, (45.56±10.86) kU/L vs (3.30±7.63) kU/L, P<0.01] were significantly higher than that of the RC group, while the level of TAM was remarkably elevated in PC group than in RC group [PC vs RC, (124.84±5.19) U/ml vs (102.44±3.63) U/ml, P<0.001] and CRA group [PC vs CRA, (124.84±5.19) U/ml vs (95.39±8.42) U/ml, P<0.01]. The LEfSe analysis showed that the featured microbiota in the PC group included f_Bacteroidaceae, f_Neisseriaceae, f_Clostridiaceae_1, f_Spirochaetaceae, and so on. The largest area under the ROC belonged to the combination of TAM and f_Bacteroidaceae, which reached 0.845 (95% CI 0.747-0.944), with sensitivity being 0.857 and specificity being 0.815. Conclusions:There is heterogeneity in gut microbiota composition among PC, DC, RC, and CRA. The combination of gut microbiota and tumor biomarkers demonstrated good differentiating effects in proximal colon cancers.