Incidence and Mortality
Primary liver cancer is the sixth most common cancer in the world, and in 2008 an estimated 750,000 people were diagnosed worldwide. The disease is more common in parts of Southeast Asia (China, Hong Kong, Taiwan, Korea and Japan) and sub-Saharan Africa (Mozambique and South Africa). Large increases in incidence, especially in younger age groups, have been observed in the USA primarily due to heavy alcohol intake, rising obesity, diabetes and hepatitis C infections. It is the third most common cause of cancer-related death worldwide.
Risk Factors
Liver cancer is more prevalent in men and is more frequent with increasing age. The main risk factors for liver cancer include infections with hepatitis B and C, heavy alcohol intake, and consumption of aflatoxin contaminated foods such as maize and nuts. Over 300 million people are currently chronically infected with the hepatitis B virus and there are over 150 million people who are chronically infected with the hepatitis C virus. These people are at a high risk of chronic inflammation, cirrhosis and liver cancer.
Diagnosis
Diagnosis of liver tumour usually starts with a physical examination and imaging scans, such as ultrasound, to look for masses in the liver. Blood tests to measure levels of alpha fetoprotein (AFP) and other liver function tests may also be used to aid diagnosis of liver malignancy. More detailed CT and MRI imaging is applied to provide precise information about the size, shape and location of any tumours in the liver and surrounding tissues. Invasive diagnostic methods, such as laparoscopy and biopsy, are available but less frequently chosen to accurately diagnose liver cancer.
There are no widely recommended screening tests to detect liver cancer at an early stage. AFP blood tests and ultrasound have been recommended worldwide for people at a higher risk, but the use and accuracy of AFP for screening are being questioned. Some liver tumours, especially early liver cancer, do not produce high enough levels of AFP to signify the presence of the tumour, while other non-cancerous diseases can also raise AFP levels.
Types of Liver Cancer
85% of currently diagnosed liver cancers are derived from liver cells, hepatocytes, and are called hepatocellular carcinoma (Hepatoma). Other types of liver cancer include cholangiocarcinoma which develops in the cells surrounding the bile duct. Angiosarcoma develops from blood vessels in the liver, while hepatoblastoma develops predominantly in children under the age of three and is more easily treatable.
Prognosis
The prognosis for liver cancer is poor irrespectively of geographical location. Liver malignancy is often diagnosed at a late stage when it shows resistance to conventional chemotherapy and treatment options are limited. Only 10% of people are diagnosed at an early stage when the tumour can be surgically removed. The 5-year survival rate for patients with localised liver cancer is 21% and it decreases for regional and distant tumours to 6% and 2% respectively.
