Reactive oxygen species also cause epigenetic alterations at the sites of DNA repair.While this constant cycle of damage followed by repair can lead to mistakes during repair, which in turn lead to carcinogenesis, this hypothesis is more applicable, at present, to hepatitis C. Chronic hepatitis C causes HCC through the stage of cirrhosis. In chronic hepatitis B, however, the integration of the viral genome into infected cells can directly induce a noncirrhotic liver to develop HCC. Alternatively, repeated consumption of large amounts of ethanol can have a similar effect. The toxin aflatoxin from certain Aspergillus species of fungi is a carcinogen and aids carcinogenesis of hepatocellular cancer by building up in the liver. The combined high prevalence of rates of aflatoxin and hepatitis B in settings such as  China and West Africa has led to relatively high rates of hepatocellular carcinoma in these regions. Other viral hepatitides such as hepatitis A have no potential to become a chronic infection, thus are not related to HCC. Diagnosis
Methods of diagnosis in HCC have evolved with the improvement in medical imaging. The evaluation of both asymptomatic patients and those with symptoms of liver disease involves blood testing and imaging evaluation. Historically, a biopsy of a tumor was required to prove an HCC diagnosis. However, imaging (especially MRI) findings may be conclusive enough to obviate histopathologic confirmation. Screening
HCC remains associated with a high mortality rate, in part because initial diagnosis commonly occurs at an advanced stage of disease.
Other
Portal vein embolization (PVE): This technique is sometimes used to increase the volume of healthy liver, in order to improve chances of survival following surgical removal of diseased liver. For example, embolization of the right main portal vein would result in compensatory hypertrophy of the left lobe, which may qualify the patient for a partial hepatectomy. Embolization is performed by an interventional radiologist using a percutaneous transhepatic approach. This procedure can also serve as a bridge to transplant. High intensity focused ultrasound (HIFU) (as opposed to diagnostic ultrasound) is an experimental technique which uses high-powered ultrasound waves to destroy tumor tissue. A systematic review assessed 12 articles involving a total of 318 patients with hepatocellular carcinoma treated with Yttrium-90 radioembolization. Excluding a study of only one patient, post-treatment CT evaluation of the tumor showed a response ranging from 29 to 100% of patients evaluated, with all but two studies showing a response of 71% or greater. Prognosis
The usual outcome is poor because only 10–20% of hepatocellular carcinomas can be removed completely using surgery. If the cancer cannot be completely removed, the disease is usually deadly within 3 to 6 months. This is partially due to late presentation with tumors, but also the lack of medical expertise and facilities in the regions with high HCC prevalence. However, survival can vary, and occasionally people survive much longer than 6 months. The prognosis for metastatic or unresectable HCC has improved due to the approval of Sorafenib (Nexavar®) for advanced HCC. Epidemiology
HCC is one of the most common tumors worldwide.