Liver Cancer

Types of liver cancer

Malignant, or cancerous, liver tumours fall into the following two types.

1. Primary or metastatic. Primary tumours originate in the liver itself
2. Hepatocellular carcinoma is the most common type of primary liver cancer

Metastatic, or secondary, liver tumours have spread to the liver from a cancer elsewhere in the body. Because one of the liver's main functions is to filter blood, cancer cells from other parts of the body may become lodged in the liver and become tumours. The most common type of metastatic liver tumours are those caused by colon cancer that has spread to the liver.

Primary liver cancer, or hepatocellular carcinoma, is the most common type of cancer originating in the liver itself. (Most tumours in the liver do not originate there; they start elsewhere in the body and spread, or metastasize, to the liver.). Worldwide, hepatocellular carcinoma is the most common solid organ tumour. This is believed to be due to widespread viral hepatitis infection, a known risk factor for primary liver cancer.

Most primary liver cancers originate in the liver's parenchymal cells, the cells that perform most of the organ's blood-filtering functions. Other rarer forms of primary liver cancer include peripheral cholangiocarcinoma (tumours in the sections of the bile ducts that are within the liver), sarcomas and angiosarcomas (cancer in the connective tissue of the liver), hemangioendotheliomas (tumours that arise in the blood vessels of the liver), and hepatoblastomas (a highly curable form of liver cancer most often found in children).

Hepatocellular carcinoma most commonly occurs in people whose livers have been damaged. This damage may be caused by alcohol abuse, by chronic infection with the hepatitis B or hepatitis C virus, from food contaminants called aflatoxins, or from metabolic diseases. Cancer can spread from the liver to other areas in the body through the blood or the lymph system, most often to the lungs, bones, and abdomen.

Several benign, or non-cancerous, tumours can occur in the liver. The most common form of benign tumour is called a hemangioma. Hemangiomas can occur anywhere in the body but occur most frequently in the skin and subcutaneous tissues (tissues beneath the skin). In nearly all cases, hemangiomas of the liver are harmless. In only rare instances do they cause pain or other problems. Once checked and deemed harmless, they can be left alone.

Symptoms

• Many patients with primary liver cancer have no symptoms.
• In some instances, jaundice, malaise, or a general feeling of poor health, loss of appetite, weight loss, fever, fatigue, bloating, itching, swelling of the legs, or weakness may be present.
• Abdominal pain or discomfort may also occur.

Risk Factor

• Hepatocellular cancer is one of the most common cancers in the world. As hepatitis B virus and hepatitis C are known risk factors for liver cancer, areas with higher rates of these infectious diseases.
• Viral hepatitis is often a silent disease. The hepatitis virus can be present in the body for years and cause no pain or symptoms.
• Viral hepatitis is contracted through contact with infected blood or body fluids. In many cases, people became infected through blood transfusions administered before 1992 (before blood was first routinely screened for the disease).
• Intravenous drug users may become infected through contact with unsterilized needles.
• Early in the infection hepatitis B can be treated with a combination of the anti-viral drugs alpha-interferon and ribavirin.
• In some cases the virus can be eradicated from the bloodstream and eliminated from the body.
• For this reason, doctors recommend that people at a high risk for developing the disease be screened.
• If the infection progresses, it can lead to chronic liver disease, or cirrhosis, a progressive disease of the liver, and, eventually, liver cancer.
• There is also a vaccine for hepatitis B. Doctors recommend that children, and those at high risk for developing the disease be vaccinated.
• The risk of primary liver cancer is greater for those whose livers have been damaged by excessive alcohol consumption.
• Approximately 15 percent of alcoholics will develop cirrhosis of the liver. Cirrhosis also makes the surgical treatment of primary liver cancer more difficult.

Diagnosis

Diagnosis of primary liver cancer is generally made using blood tests, diagnostic imaging, surgical biopsy or laparoscopy, or a combination of the above. The alpha-fetoprotein blood test and ultrasound imaging of the liver are also used to screen high-risk populations (including those with hepatitis B and hepatitis C infections) for the disease. Since the risk of liver cancer is relatively low for healthy individuals, these tests are not used to screen the general population.

The alpha-fetoprotein (AFP) blood test measures the level in the blood of a certain protein produced by the liver. Elevated levels of AFP can be an indication of hepatocellular carcinoma, the most common type of primary liver cancer. If liver cancer is suspected, other blood tests are done to measure liver function. These tests can help doctors determine the condition of the liver. Since successful treatment for liver cancer involves removing a substantial part of the normal liver tissue in addition to the cancer, other treatments might be used in people with blood tests that indicate a high degree of liver disease.

As non-invasive diagnostic imaging techniques have become more sophisticated, they can be used to gather important information about a newly diagnosed tumour,including its exact size, and density. These techniques can also be used to gauge how well a tumour will respond to treatment.

In some cases, diagnosis is performed invasively, by removing a small amount of tissue for a biopsy, or by laparoscopy (insertion of a small tube with an attached camera into the abdomen to survey the cancer site). Laparoscopy can also be used to remove a sample of tissue for biopsy.

Non-invasive Diagnostic Imaging Techniques

CT (computed tomography) scanning is useful for determining the extent of tumour growth within the gallbladder or bile duct. It can also be used to tell whether tumour cells have spread into the lymph nodes or other nearby parts of the body.

MRI (magnetic resonance imaging) can be used to determine if a tumour can be surgically removed. It shows the extent of tumour growth within the gallbladder or bile duct and reveals whether the tumour has invaded any blood vessels

Magnetic resonance cholangiopancreotography (MRCP) -- gives a detailed examination of the bile ducts. It is useful for determining the stage of a tumour in the bile duct.

Ultrasound -- useful for detecting the location and number of tumours as well as tumour involvement with blood vessels (tumours situated close to blood vessels may be more difficult to remove). It can also be used to distinguish a cancerous mass from a benign tumour.

Invasive Diagnostic Techniques

Biopsy - a small amount of tissue is removed from a specific area of the body so it can be examined more closely.

Endoscopy - the interior lining of a body cavity, such as the esophagus, stomach, bile duct, or colon, is examined using a device called an endoscope

Laparoscopy - allows for the examination of the abdominal cavity and its contents. A tube with an attached camera (called a laparascope) is passed through an incision made in the abdominal wall.

Cholangiography - a needle is inserted into the bile ducts within the liver. The ducts are injected with dye so they can be seen more clearly.

Treatment

For treatment purposes, primary liver tumours are classified in four ways. Localized and resectable tumours are found in one place and can be removed. Localized and unresectable tumours are found in one area but cannot be totally removed safely. In advanced cases, cancer has spread throughout the liver and/or to other parts of the body. In recurrent cases, the cancer has returned to the liver or another part of the body after initial treatment.

Surgery

Most primary liver cancers are best treated by surgery to remove the diseased portion of the liver. Until the early 1980s, surgery to remove primary liver tumours was rarely done. But now highly complex liver operations are performed with great frequency, success, and safety.

Operating on the liver can be difficult for several reasons. Many of the major blood vessels to and from the heart pass behind or through the liver, so in essence, the liver is "attached" to the heart. Also, the anatomy of the liver is not always obvious from the surface. The organ is large, dense, and delicate, and covered in part by the rib cage. It bleeds profusely when injured and it tears easily.

The liver has the capacity to regenerate: Up to 80 percent of the organ can be surgically removed and within several weeks, the liver will have entirely regenerated itself. If one lobe- along with its associated blood vessels - is surgically removed, the remaining lobe will compensate for the loss. A new technique which stimulates regeneration before surgery is also being evaluated here. The technique is called pre-operative portal vein embolization. If doctors feel the portion of the liver remaining after resection would be too small to allow for a good outcome, they can shift the blood supply to the normal portion of the liver before the resection is done. That normal area grows larger, and when it reaches sufficient size, the resection can be performed.

When the liver is burdened with another disease aside from the cancer, surgery is complicated and sometimes impossible. A disease such as cirrhosis dramatically weakens the liver and often leaves it permanently damaged, with limited regenerative capacity. A patient with a liver hampered by both cirrhosis and a tumour is more likely to be treated with a method other than surgery. Some of these treatments are listed below.

Ablative Therapies

Ablation uses a chemical agent or energy to destroy a tumour. Ablative procedures can be performed both percutaneously (through the skin without an incision) or during surgery. Procedures which can be performed percutaneously include cryosurgery (freezing and killing the tumour cells), radiofrequency (RF) ablation, alcohol ablation, and embolization. These therapies can be very effective but are usually intended to control cancer rather than cure it.

Ablative therapies can be used alone or in combination with surgical removal of a tumour. For example, a patient with hepatocellular cancer who is not a candidate for surgery may first be treated with embolization to shrink the tumour so that it is small enough to make another form of ablative therapy or surgery possible.

In cryosurgery, a needle is introduced into the middle of a tumour to freeze it. Residual tumour cells can be left behind, making this method less effective than surgery. It can also be difficult to keep the tumour at temperatures low enough to completely freeze it, since tumours are often near large blood vessels. Nevertheless, cryosurgery can be a very effective way to control liver tumours.

Radio frequency ablation is the opposite of cryosurgery. Rather than freezing the tumour, physicians use radio waves to heat it up to such a high temperature that the tumour is destroyed. RF ablation is effective, but can only be used for smaller tumours. This therapy is not curative; it is intended to control tumour growth.

Alcohol ablation or PEIT (percutaneous ethanol injection treatment) is a means of administering toxins directly to a tumour. It is quite effective for small tumours of less than 5 cm. This treatment is usually selected for patients who are not candidates for surgery.

Radiation Therapy

Radiation therapy is used in selected cases to help control tumours. Radiation oncologists here use new techniques to focus the radiation beam on the tumour and spare the normal liver from injury.

Embolization

Embolization is a procedure that cuts off the blood supply to the tumour. Physicians pack a branch of the hepatic artery -- the main artery that carries blood to the liver -- with tiny plastic particles, cutting off most of the blood flow and depriving the tumour of life-giving oxygen.

Source: TATA Memorial Hospital