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on the hepatoma carcinogenesis is cattle. However, this can induce hepatoma carcinogenesis. [21,22] In humans, there are
[12]
is not the finding in human beings. Kabaalioglu et al. some reports on positive correlation between schistosomiasis
studied on human fascioliasis and concluded that “long-term and hepatoma. [23-32] Since the induction of liver fibrosis in
complications are rare in fascioliasis, and malignancy or human due to schistosomiasis is observed, it is proposed
cirrhosis related to the disease has not been observed.” that this pathology can be the underlying cause of hepatoma
which may occur in future. [25-27] In a case-control study by
HEPATOMA AND OPISTHORCHIASIS Khella et al., it was found that the history of schistosomiasis
[26]
is significantly different between case and control. A similar
Liver fluke infestation or opisthorchiasis is another important observation was also reported by el-Zayadi et al. Badawi and
[31]
parasitic infestation. It is common in Indochina and has Michael found that schistosomiasis increased the severity
[30]
been proved for its relationship in the occurrence of of HBV infection and elevated the risk of HCC associated
cholangiocarcinoma. However, the role of opisthorchiasis with the HBV infection. However, Nakashima et al. [24] studied
[13]
on hepatoma carcinogenesis is still not conclusive at necropsies with hepatoma coincident with schistosomiasis,
present. There are some reports on co-incidences between and concluded that chronic schistosomiasis, on its own,
opisthorchiasis and hepatoma. [14,15] Nevertheless, the is unlikely to be the cause of primary liver cell carcinoma.
epidemiological investigation still reveals no clear evidence Nakashima et al. also reported that HCC related to viral
[32]
that opisthorchiasis can induce hepatoma carcinogenesis. hepatitis B and/or C also increased in cases with underlying
[16]
[33]
Suksumek et al. recently studied Opisthorchis viverrini DNA in schistosomiasis. Yosry concluded that there is inadequate
patients with hepatocellular carcinoma (HCC) and found that evidence for the carcinogenicity of Schistosoma mansoni
the presence of parasite had no relationship to any cancer. In in humans. S. mansoni may still be linked to HCC through
fact, the finding by Suksumek et al. is not surprising since potentiating effects of HBV and hepatitis C virus (HCV) on
[16]
the main mechanism of cholangiocarcinoma carcinogenesis is the liver. El-Tonsy et al. [34] concluded that schistosomiasis
due to chronic biliary tract irritation by parasitic infestation. accelerates hepatic dysplastic changes in the presence of
Since the O. viverrini does not infest in hepatic parenchyma, other risk factors making cancer appear early and with a more
the induction of the HCC should not occur. aggressive nature, compared to the same risk in absence
of schistosomiasis. Therefore, it can be summarized that
HEPATOMA AND CLONORCHAIASIS superimposing the effects of HBV and HCV on the liver can
be expected in the cases with combined schistosomiasis and
Similar to opisthorchiasis, clonorchiasis is known for its hepatitis virus infection. [33]
relationship with cholangiocarcinoma carcinogenesis. The
[17]
mechanism is the same as that described in opisthorchiasis Conclusively, schistosomiasis can induce liver fibrosis, which is
model. For hepatoma, there are some reports on the a precancerous lesion. In addition, chronic schistosomiasis is
co-incidence between clonorchiasis and hepatoma. However, common. The increased argyrophilic nucleolar organizer
[18]
the role of clonorchiasis in hepatoma carcinogenesis is still regions proteins which related to increased dysplasia can
controversial. A recent report by Ta n et al. concluded that be observed in the chronic schistosomiasis. In addition,
[19]
[35]
clonorchiasis could be an important risk factor for hepatoma. new observation on the deteriorating immunological status
When the course of clonorchiasis is prolonged, the risk of in chronic schistosomiasis is also reported. Dysregulation
[36]
hepatoma could increase. Hepatitis B virus (HBV) infection, of cellular immune responses, impaired T-lymphocytes and
[19]
alcohol consumption, and clonorchiasis might have synergistic natural killer cells, can be seen in the patients and can ease
actions in the development of hepatoma. Chen et al. found the occurrence of cancer. The poor immunity is said to
[36]
[20]
[19]
that excretory/secretory products of the parasite might plays an be partially due to the poor nutritional status, which
[37]
important role in hepatoma carcinogenesis. However, the study is a common complication in chronic schistosomiasis. [38]
reported by Chen et al. is only an in vitro study. Chen et al. Hence, it is no doubt that schistosomiasis can be the cause
[20]
[20]
noted that “Csseverin”, an important excretory/secretory of hepatoma carcinogenesis. Focusing on the case with
products, might exacerbate hepatoma carcinogenesis, combined chronic schistosomiasis and chronic hepatitis B or
however, this is only a speculation at this point. hepatitis C infection, a more severe liver pathology can be
expected. The precancerous liver pathological change due to
HEPATOMA AND SCHISTOSOMIASIS hepatitis virus can be superimposed by liver fibrosis induced
by schistosomiasis and this should be the explanation for
The role of schistosomiasis on hepatoma carcinogenesis is finding that schistosomiasis increase the severity of hepatitis
widely discussed. In animals, liver cirrhosis due to infestation related hepatoma.

64 Hepatoma Research | Volume 1 | Issue 2 | July 15, 2015