The most common primary
malignant tumor of the liver is a hepatocellular carcinoma. Primary
liver cancer accounts for less than 1% of all cancers in this country.
However, in other parts of the world such as Africa, Southeast Asia, and
China, it is a major health problem, causing up to 50% of cancer cases
seen in those areas. This difference is thought to be due to the much higher
percentage of the population who are carriers of the hepatitis
B virus, which predisposes to the development of hepatocellular carcinoma.
It was recognized a number
of years ago that chronic carriers of the hepatitis B virus, particularly
those with chronic hepatitis or cirrhosis, are at substantially increased
risk to develop hepatocellular carcinoma. Recent evidence indicates that
patients who have long-standing chronic hepatitis C virus infection are also at increased risk for the development of hepatocellular
carcinoma, although the exact risk is uncertain.
Certain toxins and chemicals
are also rarely associated with liver cancer. In Africa, aflatoxin, a product
of mold found in badly stored peanuts or other foods, has been recognized
as a cause of liver cancer.
Finally, certain diseases other
than chronic hepatitis B or C are associated with an increased risk of
hepatocellular carcinoma. Iron overload cirrhosis(hemochromatosis)is
associated with a substantial risk of hepatocellular carcinoma once cirrhosis
has developed. Patients with long-standing alcoholic
cirrhosis are also at risk for developing this tumor. Two congenital
disorders, alpha1-antitrypsin deficiency and tyrosinemia, may also be complicated
by the development of hepatocellular carcinoma.
Metastatic or secondary tumors
of the liver come from cancers originating elsewhere in the body. Because
the liver filters blood from all parts of the body, it is often the site
in which cancer cells will lodge and develop into metastatic nodules. An
enlarged liver secondary to cancer may be an early sign of cancer in other
organs. Secondary or metastatic cancer should not be confused with primary
cancer of the liver.
Primary liver cancer may be
detected by screening high risk patients or by chance on an imaging study
of the abdomen performed for another reason, or it may be detected because
of symptoms such as abdominal pain. Studies performed in several countries
have demonstrated that the periodic use of abdominal ultrasound and a blood
tumor marker, called alpha-fetoprotein, may lead to the early detection
of small hepatocellular carcinomas in patients at high risk. This screening
strategy has not been widely adopted because its cost effectiveness has
yet to be proven. In patients who develop symptoms from more advanced hepatocellular
carcinoma, weight loss, periodic severe pain and other generalized symptoms
may occur. Health may deteriorate rapidly and jaundice (yellow skin) may
appear.
The diagnosis of primary cancer of the liver is
typically made by liver imaging tests, such as abdominal ultrasound and
CT scan in combination with the measurement of blood levels of alpha-fetoprotein.
The final diagnosis is confirmed by needle biopsy, which is typically performed
by a radiologist who can direct the biopsy needle to the exact position
of the tumor. It may be necessary to also examine the arteries and veins
of the liver by hepatic arteriography, particularly if surgery is considered.
Treatment of primary cancer of the liver may be
directed towards a cure, or focused at palliation (the Relief of symptoms
and prolongation of life). When the tumor is small and limited to one lobe
of the liver, surgical removal offers a chance at cure. If the tumor is
larger or involves more than one lobe of the liver such that it cannot
be removed, liver transplantation has also been
performed. In either case, the cure rate averages only 20-30%, which has
limited somewhat the use of liver transplantation for this problem.
There are a number of newer therapies that offer
good palliation for hepatocellular carcinoma. In particular, the direct
injection of alcohol into the tumor via a small needle or the embolization
at the time of hepatic arteriography of a specific chemotherapeutic agent
(chemo-embolization) has resulted in prolonged survivals. These measures
may also be used together with either surgical resection or liver transplantation.
