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Liver cancer

THE liver is the largest solid organ in the human body. It has a rich blood supply coming from both arterial and venous systems, namely, the hepatic artery and portal vein, making it a common site of spread for cancers from other organs, such as the colon and breast.
Primary liver cancer or hepatocellular carcinoma, on the other hand, arises from the liver cells itself. Hepatocellular carcinoma or hepatoma is very common in the Asian region. The incidence of hepatomas increases with age and it is more common in men than in women. Hepatoma is strongly associated with chronic liver infection or hepatitis, especially hepatitis B and C viruses. The high incidence of chronic liver infection in Asia is the main cause of hepatomas in this region. Other important risk factors include liver cirrhosis from excessive alcohol consumption as well as ingestion of aflatoxin, a substance which is found in mouldy nuts and grain. Hepatomas, however, are not hereditary and therefore do not run in the families in absence of the above risk factors.

SYMPTOMS AND DIAGNOSIS

The symptoms of liver cancer are often non-specific. Patients may experience discomfort or pain in the right abdomen caused by an enlarged liver. They often have poor appetite and substantial weight loss. In more advanced cases, there may be fluid in the abdomen, yellowness of the eyes or bleeding from the oesophagus and stomach. The diagnosis of hepatoma is usually confirmed by imaging and blood tests. Imaging techniques such as ultrasound and CT scan will usually show either a single or multiple swellings in the liver. They may also show signs of spread of the disease, such as to the lymph nodes in the abdomen or as lung nodules.

Blood tests often show positivity for hepatitis B and a tumour marker called alpha feto-protein is often elevated.
To confirm the diagnosis of hepatoma, a tissue sample of the liver swelling can be taken by inserting a needle through the skin into the liver. The biopsy sample is then examined under the microscope. However, a biopsy may not be necessary in all cases, especially when the levels of alpha feto-protein is very high.

TREATMENT

Hepatomas may be simply staged as localised disease, locally advanced and advanced. Treatment varies according to the extent of the disease and the fitness of patients. For patients with localised disease, surgery is the treatment of choice and generally offers the only chance of cure. This involves removing the whole tumour or tumours with a margin of normal liver tissue. Sometimes a whole lobe of liver may need to be removed but as the human body requires only about 25 per cent of a normal liver to function, this can be done safely.

For locally advanced disease which cannot be removed, local therapies may be attempted to reduce the size of the tumour in the liver and relieve the patient's symptoms. These include arterial infusion of chemotherapy or lipiodol into the tumour, ultrasonic radiofrequency ablation and direct ethanol injections. Intravenous chemotherapy may also be given. However, the effectiveness of these therapies is limited and the tumours do not generally disappear with treatment. For patients with advanced hepatomas, treatment is generally aimed at relieving symptoms with prolongation of life as a secondary objective.

Hepatomas, like many other cancers, are often detected late. There is no reliable way of screening for the disease with blood tests or imaging techniques. Given its strong association with hepatitis B, a large proportion of liver cancers could be prevented by immunisation against hepatitis B. This is a very effective method of prevention against both hepatitis B and liver cancer. Prevention of this disease is far easier than its cure.

* The writer is a consultant clinical oncologist and an executive committee member of the Malaysian Oncological Society. This is the 10th instalment of a weekly series on cancer, written by members of the MOS. The 15-part series will discuss ways to manage and treat the most common forms of cancer in Malaysia.