Liver tumors

Generality

The liver is very often the site of tumors.

By far more frequent are the secondary ones - which originate in another site and metastasize the liver - but the primitive ones are not rare either; the latter arise directly in the organ and their incidence is closely related to various risk factors that we will analyze in the rest of the article.

Primary liver tumors

They can be benign or malignant, with a great prevalence of the latter, and can originate from various structures: hepatocytes (the effector cells of the liver), biliary tract (which carry bile), connective tissue of the liver or blood vessels.

Frequency of liver cancer

The disease has an "incidence of around 5 cases per 100,000 people in Western countries and even 110 cases per 100,000 in some South African countries, especially in Mozambique, where it is the most frequent cancer of all (due to the presence of many people infected with the virus of hepatitis B and hepatitis C). Italy is in an intermediate situation, with an incidence of about 20 cases per 100,000 inhabitants.

Globally, liver cancer is the third leading cause of cancer death, after lung and stomach cancer.

According to the data released in 2014 by the AIOM (Italian association of medical oncology), liver tumors in Italy:

they represent 3% of all new cases of cancer and are twice as frequent in males as in females;
unlike most cancers, this tumor has a "higher incidence in the South;
as observed for many other cancers, cases in Italy are increasing overall due to the aging population trend; net of this aspect, the "incidence of carcinoma appears to be decreasing in both sexes since the mid-1990s";
they are among the top 5 causes of cancer death only in males (7%), among which they are in fourth place (8%) in the age group 50-69 years.
17% of males and 16% of females who contracted these neoplasms are still alive 5 years after diagnosis (period 2005-2007). Compared to the previous five years, life expectancy appears to have improved proportionally, albeit in the context of a disease with a poor prognosis.

Figure: Age-standardized number of liver cancer deaths per 100,000 population. From wikipedia.org, 2004 data

Causes of liver cancer

Cirrhosis of the liver

Hepatocarcinoma, especially in Western countries, is frequently associated with cirrhosis of the liver, a disease characterized by an "alteration of the normal anatomical structure of the liver, which then causes, over the years, its malfunction until death.

Direct damage to hepatocytes is often caused by the abuse of ethyl alcohol, which in turn, over time, gives rise to cirrhosis. This disease accelerates the proliferation of liver cells, called "regeneration", by increasing the rate of synthesis of the DNA; during this process errors (aberrations) can occur, responsible for the development of a hepatocarcinoma.

In the areas of Northern Italy, about one third of liver cancers are attributable to the abuse of alcoholic beverages.

Viral hepatitis

Another cause of liver cancer is related to hepatitis B and C virus. It has been seen that where the number of carriers of viral hepatitis is high, the cases of liver tumors are equally high (a classic example is the regions of Africa where more than 10% of the population is positive for hepatitis). The virus of hepatitis B predisposes to cancer because it is able to insert itself in the DNA of hepatocytes, causing them to proliferate in an uncontrolled manner; that of hepatitis C does not integrate into the DNA, but equally promotes liver cancer with still unknown mechanisms.

Nationally, the role of hepatitis B as a cause of liver cancer is expected to decline as a result of vaccination campaigns in those born from 1978 onwards.

Hemochromatosis

Another important disease is hemochromatosis (which causes an enormous and pathological accumulation of iron in various organs, such as the liver, heart, brain, kidneys and pancreas).

Other Causes

As for food-related substances, carcinogens are certainly nitrosamines, which derive from the nitrates present in various foods, but also some mycotoxins (produced by fungi that colonize peanuts and cereals). Of the latter, the most important is "aflatoxin, a substance produced by a fungus, the"Aspergillus flavus, particularly widespread in certain tropical countries, such as Uganda; it is no coincidence that in these countries the contamination of food by aflatoxins is quite frequent (which is why primary liver cancer is widespread).

Even certain chemicals, such as "arsenic and the monomer vinyl chloride (found in the plastic processing industry), can cause, with high frequency, a liver tumor called hepatic angiosarcoma, as well as a radioactive contrast agent called Torostat, which was used in the 1940s for angiography (x-rays of blood vessels), but which is no longer used today.

Other possible carcinogenic factors are represented by prolonged treatment with hormones anabolic steroids in high doses, from cigarette smoke and above all from "alcohol.
Some parasites like Echinococcus granulosus, Schistosoma haematobium and Amoeba, can cause liver cysts, usually benign.

THE oral contraceptives they very little increase the risk of developing liver cancer, always of a benign nature.

The risk of liver cancer is also greater in the case of obesity (especially if complicated by the presence of diabetes), α-1-antitrypsin deficiency or in the case of non-alcoholic steatohepatitis (even in the absence of viral infection). Smoking has also recently been recognized as a risk factor.