Schistosoma mansoni infection: is it a risk factor for development of hepatocellular carcinoma?

The burden of hepatocellular carcinoma (HCC) in Egypt has been increasing with a doubling in the incidence rate in the past 10 years, which necessitates the investigation of the possible risk factors to its development. The present study aimed at investigating the role of Schistosoma mansoni infection as a risk factor for development of HCC. Five hundred parasite free mice were categorized into four groups: Group I (induction of carcinoma by diethylnitrosamine (DEN)), Group II (DEN+Infection), Group III (Infection) and Group IV (Control). Groups I and II were further subdivided into 4 subgroups according to the dose of DEN given. Serum samples from each group were examined for levels of tumor markers alpha fetoprotein (AFP) and ferritin by ELISA, then mice were sacrificed and subjected to histopathological examination of their livers. These were repeated every week till the end of the experiment. The results of the histopathological examination clarified the role of S. mansoni in enhancing and aggravating the carcinogenic effect of DEN; dysplastic changes appeared earlier, with a higher grade and with a smaller dose of DEN in Group II compared to Group I. Serum levels of tumor markers showed earlier statistically significant differences in Group II than in Group I when compared to Group IV. We conclude that S. mansoni accelerates hepatic dysplastic changes in the presence of other risk factors making cancer appear early and with a more aggressive nature, compared to the same risk in absence of schistosomiasis.