Liver cancer

Overview of liver cancer
Liver cancer (hepatocellular carcinoma HCC) is a cancer arising from the liver. It is also called primary liver cancer or hepatoma. The liver is composed of different types of cells in order for it to perform its functions (for example, bile ducts, blood vessels, and fat-storing cells). However, a large part of liver (around 80%) is made up of liver cells (hepatocytes). Thus, the majority of primary liver cancers (over 90 to 95%) arises from liver cells and is called hepatocellular cancer or carcinoma.
If the cancer originated from liver cells then only it’s called liver cancer, however if it spreads to liver having originated in other organs (such as the colon, stomach, pancreas, breast, and lung). This type of liver cancer is called metastatic liver disease (cancer) or secondary liver cancer. Thus, the term liver cancer actually can refer to both metastatic liver cancer and hepatocellular cancer.

Causes of liver cancer
The various reasons for liver cancer may include:
Hepatitis B infection The role of hepatitis B virus (HBV) infection in causing liver cancer is well established. The patients with hepatitis B virus who are at greatest risk for liver cancer are men with hepatitis B virus cirrhosis (scarring of the liver) and a family history of liver cancer. This genetic material of hepatitis B virus may disrupt the normal genetic material in the liver cells, thereby causing the liver cells to become cancerous. The majority of individuals who have been infected by Hepatitis B most of their lives are at a major risk.

Hepatitis C infection Hepatitis C virus (HCV) infection is also associated with the development of liver cancer.

Drugs, medications, and chemicals Liver cancers are not caused by any medication, however there are some chemicals that may cause liver cancer. For example Aflatoxin B1 is the most potent liver cancer-forming chemical known. There are cases where female hormones estrogens and protein-building (anabolic) steroids cause hepatic adenomas. These are benign liver tumors that may become malignant (cancerous). Certain chemicals are associated with other types of cancers found in the liver. For example, thorotrast, a previously used contrast agent for imaging, caused a cancer of the blood vessels in the liver called hepatic angiosarcoma. Also, vinyl chloride, a compound used in the plastics industry, can cause hepatic angiosarcomas that appear many years after the exposure.

Hemochromatosis A hereditary disease characterized by improper dietary iron metabolism (making it a iron overload disorder), which causes the accumulation of iron in a number of body tissues

Cirrhosis Cirrhosis of the liver is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrotic scar tissue as well as regenerative nodules, leading to progressive loss of liver function. Cirrhosis is most commonly caused by alcoholism and hepatitis C, but has many other possible causes.


Symptoms of liver cancer
There are variable initial symptoms (the clinical presentations) of liver cancer. Generally the liver cancer is discovered at a very advanced stage of disease. The reason for such late discovery is that areas with high rate of liver cancer have limited access to healthcare as it is generally found in developing nations. Thus, screening examinations for patients at risk for developing liver cancer are not available in these areas. Patients from these regions actually have more aggressive liver cancer disease i.e. the tumor usually reaches an advanced stage and symptoms appear rapidly. In contrast, patients in areas of low liver cancer frequency tend to have liver cancer tumors that progress more slowly and, therefore, remain without symptoms longer. Other symptoms of liver cancer are:
Abdominal pain
weight loss
fevers
The sudden appearance of ascites (abdominal fluid and swelling), jaundice (yellow color of the skin), or muscle wasting
Diagnosis of liver cancerTo diagnose liver cancer the physician according to the needs may order the following test:
Blood tests
Imaging studies
Ultrasound
MRI
Liver biopsy or aspiration

Treatment of liver cancer
Like any other cancer the liver cancer treatment are dictated by the stage of liver cancer and the overall condition of the patient. The treatment options may include:

Chemoembolization (trans-arterial chemoembolization or TACE)
Liver cancer is a very vascular (contains many blood vessels) tumor and gets its blood supply exclusively from the branches of the hepatic artery. This procedure involves blocking (embolizing) the small blood vessels with different types of compounds, such as gelfoam or even small metal coils. Thus, TACE has the advantages of exposing the tumor to high concentrations of chemotherapy and confining the agents locally since they are not carried away by the blood stream. At the same time, this technique deprives the tumor of its needed blood supply, which can result in the damage or death of the tumor cells.

Ablation techniques
Radiofrequency ablation (RFA) therapy
In the U.S., RFA therapy is performed laparoscopically (through small holes in the abdomen) or during open exploration of the abdomen. In some instances, the procedure can be done without opening the abdomen by just using ultrasound for visual guidance. In RFA, a high frequency, alternating current that flows from the electrodes generate heat locally. The local heat that is generated melts the tissue (coagulative necrosis). The whole procedure is monitored visually by ultrasound scanning. The ideal size of an liver cancer tumor for RFA is less than 3 cm. Larger tumors may require more than one session. This treatment should be viewed as palliative (providing some relief), not curative.

Percutaneous ethanol (alcohol) injection
In this technique, pure alcohol is injected into the tumor through a very thin needle with the help of ultrasound or CT visual guidance. Alcohol dehydrates the tumor by drawing water out of tumor cells. As a result the structure of cellular proteins is altered (denatured). The ideal patient for alcohol injection has fewer than three liver cancer tumors, each of which is:
- well defined (distinct margins)- less than 3 cm in diameter- surrounded by a shell consisting of scar tissue (fibrous encapsulation)- not near the surface of the liver
Patients with liver cancer undergoing alcohol injection should have no signs of chronic liver failure as patients with liver failure would not be able to tolerate the alcohol injections.

Proton beam therapy
This technique is able to deliver high doses of radiation to a defined local area. Proton beam therapy is used in the treatment of other solid tumors as well.Surgery
Surgical options are limited to individuals whose tumors are less than 5 cm and confined to the liver, with no invasion of the blood vessels.

Liver resection
The goal of liver resection is to completely remove the tumor and the appropriate surrounding liver tissue without leaving any tumor behind. This option is limited to patients with one or two small (3 cm or less) tumors and excellent liver function, ideally without associated cirrhosis. The biggest concern about resection is that following the operation, the patient can develop liver failure. The liver failure can occur if the remaining portion of the liver is inadequate to provide the necessary support for life. Even in carefully selected patients, about 10% of them are expected to die shortly after surgery, usually as a result of liver failure.
When a portion of a normal liver is removed, the remaining liver can grow back (regenerate) to the original size within one to two weeks. A cirrhotic liver, however, cannot grow back. Therefore, before resection is performed for liver cancer, the non-tumor portion of the liver should be biopsied to determine whether there is associated cirrhosis.

Liver transplantation
Patients with various diseases like chronic hepatitis B and C, alcoholic cirrhosis, primary biliary cirrhosis, and sclerosing cholangitis undergo liver transplantation.
In summary, liver resection should be reserved for patients with small tumors and normal liver function (no evidence of cirrhosis). Patients with multiple or large tumors should receive palliative therapy with intra-arterial chemotherapy or TACE, provided they do not have signs of severe liver failure. Patients with an early stage of cancer and signs of chronic liver disease should receive palliative treatment and undergo evaluation for liver transplantation.

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