Schistosoma Japonicum Infection is a Critical Risk Factor for Presence and Pathologic Subtypes Redistribution of Colorectal Cancer in Rural China

Background: Infection of Schistosome japonicum (S. japonicum) had been endemic in China. However, the association between Schistosome japonicum (S. japonicum) infection and the epidemiology or pathologic features of colorectal cancer was unknown. Methods: A cross-sectional survey was carried out in 220,175 participants aged 45 years and older in Songjiang County of Shanghai, an endemic region of schistosome infection. Furthermore, schistosome infection associated pathologic subtypes of colorectal cancer were also analyzed among participants. Findings: In cross-sectional survey, 9,986 subjects were defined as having previous schistosome infection, of which 249 were diagnosed as having colorectal cancer, and the overall prevalence of colorectal cancer was 2.49%. While remaining 210,189 participants without schistosome infection, 885 also suffered from colorectal cancer, and the corresponding rate was only 0.42%. Unconditional logistic regression analysis suggested a strong association between the infection and risk of colorectal cancer, with an adjusted OR of 4.248 and 95% CI of 3.656-4.935. Furthermore, compared with colorectal cancer without schistosome infection, there was a high percentage of mucinous adenocarcinoma (21.4% vs 11.8%, adjusted OR = 2.149, 95% CI = 1.474-3.134) and signet-ring cell carcinoma with schistosome infection (4.5% vs 1.1%, adjusted OR = 5.341, 95% CI = 2.145-13.296). Notably, mucinous adenocarcinoma in rectum showed a higher proportion (27.5% vs 8.2%). By contrast, signet-ring cell carcinoma had a predilection to occur in sigmoid colon (16.7% vs 0). Interpretation: S. japonicum infection is a critical risk factor and a pathologic subtype redistribution driver of colorectal cancer. Moreover, these redistributions have location-specificity and higher mucus secretion. Funding: None Declaration of Interest: We declare no competing interests. Ethical Approval: The institutional review board or ethics committee at each of the participating institutions approved the study protocol. Written informed consent was obtained from each participant before data collection.