Fusobacterium nucleatum in Colorectal Carcinoma Tissue According to Tumor Location

Objectives: Evidence suggests a possible role of Fusobacterium nucleatum in colorectal carcinogenesis, especially in right-sided proximal colorectum. Considering a change in bowel contents and microbiome from proximal to distal colorectal segments, we hypothesized that the proportion of colorectal carcinoma enriched with F. nucleatum might gradually increase along the bowel subsites from rectum to cecum. Methods: A retrospective, cross-sectional analysis was conducted on 1,102 colon and rectal carcinomas in molecular pathological epidemiology databases of the Nurses’ Health Study and the Health Professionals Follow-up Study. We measured the amount of F. nucleatum DNA in colorectal tumor tissue using a quantitative PCR assay and equally dichotomized F. nucleatum-positive cases (high vs. low). We used multivariable logistic regression analysis to examine the relationship of a bowel subsite variable (rectum, rectosigmoid junction, sigmoid colon, descending colon, splenic flexure, transverse colon, hepatic flexure, ascending colon, and cecum) with the amount of F. nucleatum. Results: The proportion of F. nucleatum-high colorectal cancers gradually increased from rectal cancers (2.5% 4/157) to cecal cancers (11% 19/178), with a statistically significant linear trend along all subsites (P