What’s liver cancer and its Risk Factors?
Liver cancer is a highly prevalent tumor with a poor prognosis. It is the fifth most common and the fourth leading cause of cancer death. Liver cirrhosis underlies in most cases.
Liver cancer, hepatocellular carcinoma, or hepatocellular carcinoma are different names for liver cancer. We are talking about the most frequent primary malignant liver tumor, far ahead of other hepatic malignant tumors such as lymphangiosarcoma, angiosarcoma, hepatoblastoma, etc. However, the most frequent neoplastic disease at the liver level is metastases or primary tumors of another origin.
The data confirm that it is a highly prevalent tumor with a poor prognosis. It is the 5th most frequent and the 4th cause of death from cancer. There are great differences concerning its incidence according to regions, and thus we can distinguish countries with:
- High incidence: (> 20 cases / 100,000 inhabitants / year): Asia, Japan and sub-Saharan Africa.
- A medium-high incidence (11-20 cases): Spain, Italy, and Latin America.
- Low, medium incidence (5-10 cases): France, Germany, and the United Kingdom.
- Low incidence (<5 cases): USA, Canada, and Scandinavian countries.
Risk factors for liver cancer
The most frequent triggering cause of liver cancer is liver cirrhosis. This disease underlies most of those affected by this tumor, especially in viral and alcoholic hepatitis cases. However, not all cirrhosis ends in liver cancer, or all hepatocarcinoma is based on cirrhosis. These are the other risk factors for liver cancer (CH):
Hepatitis C virus (HCV)
Almost 170 million people infected with the hepatitis C virus (HCV), only 20% will develop liver cirrhosis. These are those with the highest risk of developing liver cancer (between 1% and 4% per year). In our set of all hepatocarcinoma diagnoses, 65% present anti-HCV antibodies. It seems that HCV exerts an intrinsic carcinogenic action, independent of the fact of developing cirrhosis, due to phenomena that prevent programmed cell death (apoptosis) and due to pro-inflammatory phenomena. However, the vast majority of liver cancer cases in people with hepatitis C virus infection occur when the liver’s cirrhosis is already present.
Hepatitis B virus (HBV)
It is the primary causative agent of liver cancer worldwide. In Western countries, we have already commented that the most frequent cause is HCV. The World Health Organization considers it the second most potent carcinogen after tobacco. The problem is that the population (mainly in East Asian countries) acquires HBV at a very early age, which becomes chronic; Thus, those affected are exposed for many years to the damage caused by chronic liver inflammation, cirrhosis, and liver cancer. A study shows that the risk of liver cancer is 100 times higher in carriers of antigen against the hepatitis B virus than in non-carriers.
Carcinogenesis is due to chronic inflammation mediated by the immune response, which is insufficient to eliminate the virus but is sufficient to perpetuate hepatocyte death and accelerated cell turnover with increased risk of genetic alterations. Also, HBV is a direct carcinogen since it integrates into the hepatocyte genome (not like HCV) and can induce liver cancer without causing previous cirrhosis. The risk varies depending on multiple factors such as viral load or the type of strain (viral genotype). The trouble is reduced if a seroconversion occurs, that is, if a patient can control the disease and antibodies to the hepatitis B antigen appear or if seroconversion has occurred.
Aflatoxin
Toxins produced by fungi of the genus Aspergillus are abundant in plant foods improperly stored in humid environments. It is carcinogenic, as it has a mutation of the p53 tumor suppressor gene. It is very common in sub-Saharan Africa and Asia.
Other causes of liver cancer
Tobacco, insulin resistance, schistosomiasis (a common parasitic disease in Africa and some parts of Latin America and the Middle East), iron overload (as in hemochromatosis ), dietary factors, drugs, and chemicals, and so on.