الفهرس 
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Abstract
As reviewed, the global burden of cancer associated with infectious agents approaches 20% of all malignancies. However, several parasites have been linked to oncogenesis in human; some of these associations are strong as in case of Schistosoma haematobium. It had been recognized as a definitive cause of urinary bladder cancer by the IARC. The relative risk for bladder cancer in S. haematobium infected patients is estimated between 1.8 and 23.5. It has been calculated that 3% of bladder cancers around the world are attributable to S. haematobium.
The association between Schistosoma mansoni infection and HCC appears to be indirect. Patients with S. mansoni have higher incidence of HBV or HCV infection (two viruses associated with carcinogenesis process), compared to noninfected controls. The role of Schistosoma japonicum in cancer occurrence is less clear, although this parasite has been associated with both liver and colorectal cancer. Some epidemiological and clinical studies in China and Japan support its role as one of the risk factors in HCC formation. Experimental studies have shown that liver cancer appears early in experimentally S. japonicum infected animals.
Opisthorchiidae are liver flukes found in the bile duct of domestic and wild animals but also in humans. Opistorchis viverrini, O. felineus and Clonorchis sinensis are the most concerned species. In addition to their association with hepatobiliary disease, they are considered as major etiological agents of hepatic CCA. After evaluating epidemiological studies, case series, and case control studies, O. viverrini was considered definitely carcinogenic by the IARC.