RESUMEN
Objective@#To explore the interaction of multi-target stool DNA (MT-sDNA), intestinal flora and environmental factors in the development of colorectal cancer, so as to provide insights into pathogenesis study of colorectal cancer.@*Methods@#A total of 54 cases of colorectal cancer from the First Affiliated Hospital of Ningbo University were included in the case group and 51 healthy subjects were included in the control group. Demographic information, diet and family history of colorectal cancer were collected by a questionnaire survey. MT-sDNA, intestinal flora, cancer antigen 19-9 (CA19-9), carcinoembryonic antigen (CEA) and other tumor markers were detected. Interactions of MT-sDNA, intestinal flora and environmental factors with the development of colorectal cancer was analyzed by multifactor dimensionality reduction (MDR), crossover analysis and additive model.@*Results@#The case group included 20 males (37.04%) and 34 females (62.96%), and had a mean age of (64.89±9.72) years. The control group included 24 males (47.06%) and 27 females (52.94%), and had a mean age of (53.94±10.33) years. MDR analysis showed that subjects with both high absolute intestinal flora indexes and positive MT-sDNA had an increased risk of colorectal cancer (OR=3.782, 95%CI: 1.190-5.034). Crossover analysis showed that subjects with positive MT-sDNA and >5 μg/L of CEA had an increased risk of colorectal cancer (OR=2.121, 95%CI: 1.162-4.033). Additive model analysis showed that MT-sDNA had positive additive interaction with CEA (SI=3.687, 95%CI: 1.229-7.238), and MT-sDNA had negative additive interaction with fruit intake (SI=0.145, 95%CI: 0.020-0.753).@*Conclusion@#Positive MT-sDNA can synergistically increase the risk of colorectal cancer with high intestinal flora index and CEA, and fruit intake can reduce the risk of colorectal cancer in MT-sDNA-positive population.