Liver Cancer – A MUST read!

Liver cancer (hepatocellular carcinoma) is a cancer arising from the liver. It is also known as primary liver cancer or hepatoma. The liver is made up of different cell types (for example, bile ducts, blood vessels, and fat-storing cells). However, liver cells (hepatocytes) make up 80% of the liver tissue. Thus, the majority of primary liver cancers (over 90%-95%) arises from liver cells and is called hepatocellular cancer or carcinoma.

When patients or physicians speak of liver cancer, however, they are often referring to cancer that has spread to the liver, having originated in other organs (such as the colon, stomach, pancreas, breast, and lung). More specifically, this type of liver cancer is called metastatic liver disease (cancer) or secondary liver cancer. This is a much more common problem around the world than primary liver cancer and frequently leads to confusion, because the term liver cancer actually can refer to either metastatic liver cancer or hepatocellular cancer. The subject of this article is hepatocellular carcinoma, which I will refer to as liver cancer.

What is the scope of the liver cancer problem?

Liver cancer is the third most common cancer in the world. A deadly cancer, liver cancer will kill almost all patients who have it within a year. In 2000, it was estimated that there were about 564,000 new cases of liver cancer worldwide, and a similar number of patients died as a result of this disease. About three-quarters of the cases of liver cancer are found in Southeast Asia (China, Hong Kong, Taiwan, Korea, and Japan). Liver cancer is also very common in sub-Saharan Africa (Mozambique and South Africa).

The frequency of liver cancer in Southeast Asia and sub-Saharan Africa is greater than 100 cases per 100,000 population. In contrast, the frequency of liver cancer in North America and Western Europe is much lower, less than five per 100,000 population. However, the frequency of liver cancer among native Alaskans is comparable to that seen in Southeast Asia. This reflects the prevalence of hepatitis B infection, which is the most common cause of this cancer worldwide. Recent data show, however, that the frequency of liver cancer in the U.S. overall is rising. This increase is due primarily to risingobesity and diabetes rates, and to chronic hepatitis C, another infection of the liver that causes liver cancer.

What are the population characteristics (epidemiology) of liver cancer?

In the U.S., the highest frequency of liver cancer occurs in immigrants from Asian countries, where liver cancer is common. The frequency of liver cancer among Caucasians is the lowest, whereas among African-Americans and Hispanics, it is intermediate. The frequency of liver cancer is high among Asians because liver cancer is closely linked to chronic hepatitis B infection. This is especially so in individuals who have been infected with chronic hepatitis B for most of their lives (it is usually a childhood disease in Asia). If you take a world map depicting the frequency of chronic hepatitis B infection, you can easily superimpose that map on a map showing the frequency of liver cancer. On the other hand, in Japan, North America and Europe, hepatitis C infection is a much more common cause; alcohol abuse is also an important contributing factor. All of these diseases cause continual damage to the liver, which can result in severe scarring (cirrhosis) that then can lead to cancer.

In areas where liver cancer is more common and associated with hepatitis B, the cancer usually develops in people in their 30s and 40s, as opposed to other areas of the world, where they are in their 60s and 70s. This is because it generally takes about 30 years of chronic damage to the liver before the cancer grows large enough to become obvious. Men are much more likely than women to have liver cancer, especially if they have hepatitis and cirrhosis. Regardless of the cause, patients with a history of alcohol abuse as well are much sicker when they initially develop the cancer. In North America, up to one-quarter of people with liver cancer have no obvious risk factors; they are generally healthier and do much better with treatment.

What are liver cancer causes and risk factors?

Hepatitis B infection

Hepatitis B can be caught from contaminated blood products or used needles or sexual contact but is frequent among Asian children from contamination at birth or even biting among children at play. The role of hepatitis B virus (HBV) infection in causing liver cancer is well established. Several lines of evidence point to this strong association. As noted earlier, the frequency of liver cancer relates to (correlates with) the frequency of chronic hepatitis B virus infection. In addition, 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. Perhaps the most convincing evidence, however, comes from a prospective (looking forward in time) study done in the 1970s in Taiwan involving male government employees over the age of 40. In this study, the investigators found that the risk of developing liver cancer was 200 times higher among employees who had chronic hepatitis B virus as compared to employees without chronic hepatitis B virus infection.

Studies in animals also have provided evidence that hepatitis B virus can cause liver cancer. For example, we have learned that liver cancer develops in other mammals that are naturally infected with viruses related to the hepatitis B virus. Finally, by infecting transgenic mice with certain parts of the hepatitis B virus, scientists caused liver cancer to develop in mice that do not usually develop liver cancer. (Transgenic mice are mice that have been injected with new or foreign genetic material.)

How does chronic hepatitis B virus cause liver cancer? In patients with both chronic hepatitis B virus and liver cancer, the genetic material of hepatitis B virus is frequently found to be part of the genetic material of the cancer cells. It is thought, therefore, that specific regions of the hepatitis B virus genome (genetic code) enter the genetic material of the liver cells. This hepatitis B virus genetic material may then disrupt the normal genetic material in the liver cells, thereby causing the liver cells to become cancerous.

The vast majority of liver cancer that is associated with chronic hepatitis B virus occurs in individuals who have been infected most of their lives. In areas where hepatitis B virus is not always present (endemic) in the community (for example, the U.S.), liver cancer is relatively uncommon. The reason for this is that most of the people with chronic hepatitis B virus in these areas acquired the infection as adults, and very few develop an ongoing (chronic active) infection, which happens as often as 15% of the time in Asia.

Hepatitis C infection

Hepatitis C virus (HCV) infection is more difficult to get than hepatitis B. It usually requires direct contact with infected blood, either from contaminated blood products or needles. HCV is also associated with the development of liver cancer. In fact, in Japan, hepatitis C virus is present in up to 75% of cases of liver cancer. As with hepatitis B virus, the majority of hepatitis C virus patients with liver cancer have associated cirrhosis (liver scarring). In several retrospective-prospective studies (looking backward and forward in time) of the natural history of hepatitis C, the average time to develop liver cancer after exposure to hepatitis C virus was about 28 years. The liver cancer occurred about eight to 10 years after the development of cirrhosis in these patients with hepatitis C. Several prospective European studies report that the annual incidence (occurrence over time) of liver cancer in cirrhotic hepatitis C virus patients ranges from 1.4%-2.5% per year.

In hepatitis C virus patients, the risk factors for developing liver cancer include the presence of cirrhosis, older age, male gender, elevated baseline alpha-fetoprotein level (a blood tumor marker), alcohol use, and co-infection with hepatitis B virus. Some earlier studies suggested that hepatitis C virus genotype 1b (a common genotype in the U.S.) may be a risk factor, but more recent studies do not support this finding.

The way in which hepatitis C virus causes liver cancer is not well understood. Unlike hepatitis B virus, the genetic material of hepatitis C virus is not inserted directly into the genetic material of the liver cells. It is known, however, that cirrhosis from any cause is a risk factor for the development of liver cancer. Therefore, it has been argued that hepatitis C virus, which causes cirrhosis of the liver, is an indirect cause of liver cancer.

On the other hand, there are some chronic hepatitis C virus-infected individuals who have liver cancer without cirrhosis. So, it has been suggested that the core (central) protein of hepatitis C virus is the culprit in the development of liver cancer. The core protein itself (a part of the hepatitis C virus) is thought to impede the natural process of cell death or interfere with the function of a normal tumor suppressor (inhibitor) gene (the p53 gene). The result of these actions is that the liver cells go on living and reproducing without the normal restraints, which is what happens in cancer.

Alcohol

Cirrhosis caused by chronic alcohol consumption is the most common association of liver cancer in the developed world. In fact, at autopsy, as many as half of alcoholics previously unsuspected to have cancer will have early evidence of cancer hidden within the liver. Many of these people are also infected with chronic hepatitis C virus. The usual setting is an individual with alcoholic cirrhosis who has stopped drinking for 10 years and then develops liver cancer. It is somewhat unusual for an actively drinking alcoholic to develop liver cancer. What happens is that when the drinking is stopped, the liver cells try to heal by regenerating (reproducing). It is during this active regeneration that a cancer-producing genetic change (mutation) can occur, which explains the occurrence of liver cancer after the drinking has been stopped.

More importantly, if an alcoholic does not stop drinking, he or she is unlikely to live long enough to develop the cancer. Alcoholics who are actively drinking are more likely to die from non-cancer related complications of alcoholic liver disease (for example, liver failure). Indeed, patients with alcoholic cirrhosis who die of liver cancer are about 10 years older than patients who die of non-cancer causes. Finally, as noted above, alcohol adds to the risk of developing liver cancer in patients with chronic hepatitis C virus or hepatitis B virus infections.

Aflatoxin B1

Aflatoxin B1 is the most potent liver cancer-forming chemical known. It is a product of a mold called Aspergillus flavus, which is found in food that has been stored in a hot and humid environment. This mold is found in such foods as peanuts, rice, soybeans, corn, and wheat. Aflatoxin B1 has been implicated in the development of liver cancer in Southern China and sub-Saharan Africa. It is thought to cause cancer by producing changes (mutations) in the p53 gene. These mutations work by interfering with the gene’s important tumor suppressing (inhibiting) functions.

Drugs, medications, and chemicals

There are no medications that cause liver cancer, but female hormones (estrogens) and protein-building (anabolic) steroids are associated with the development of hepatic adenomas. These are benign liver tumors that may have the potential to become malignant (cancerous). Thus, in some individuals, hepatic adenoma can evolve into cancer.

Certain chemicals are associated with other types of cancers found in the liver. For example, thorotrast, a previously used contrast agent for diagnostic imaging studies, 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

Liver cancer will develop in up to 30% of patients with hereditary hemochromatosis (a disorder in which there is too much iron stored in the body, including in the liver). Patients at the greatest risk are those who develop cirrhosis with their hemochromatosis. Unfortunately, once cirrhosis is established, effective removal of excess iron (the treatment for hemochromatosis) will not reduce the risk of developing liver cancer.

Diabetes and obesity

Over the past decade, the incidence of liver cancer in the United States has risen significantly, paralleling the rise in obesity. Although it is hard to separate the effects of diabetes from obesity on the liver, both conditions can cause chronic damage and accumulation of fat within the liver.. This is a disease called NASH (non-alcoholic steatohepatitis), which is present in up to 5% of North Americans. Fatty liver disease like this causes damage to the individual liver cells and may lead to cirrhosis in some people, thereby increasing the risk of liver cancer. Not only is the chance of developing the cancer enhanced, but patients with diabetes who undergo surgical removal of liver cancer have a higher chance of the cancer returning than do those without diabetes.

Cirrhosis

Individuals with most types of cirrhosis of the liver are at an increased risk of developing liver cancer. In addition to the conditions described above (hepatitis B, hepatitis C, alcohol, and hemochromatosis), alpha 1 anti-trypsin deficiency, a hereditary condition that can cause emphysema and cirrhosis, may lead to liver cancer. Liver cancer is also strongly associated with hereditary tyrosinemia, a childhood biochemical abnormality that results in early cirrhosis.

Certain causes of cirrhosis are less frequently associated with liver cancer than are other causes. For example, liver cancer is rarely seen with the cirrhosis in Wilson’s disease (abnormal copper metabolism) or primary sclerosing cholangitis (chronic scarring and narrowing of the bile ducts). It used to be thought that liver cancer is rarely found in primary biliary cirrhosis(PBC) as well. Recent studies, however, show that the frequency of liver cancer in PBC is comparable to that in other forms of cirrhosis.

What are liver cancer symptoms and signs?

The initial symptoms (the clinical presentations) of liver cancer are variable. It is becoming much more common for patients to be identified by screening people at high risk for the cancer and finding the cancer before there are any symptoms at all. In countries where liver cancer is very common, the cancer generally is discovered at a very advanced stage of disease for several reasons. For one thing, areas where there is a high frequency of liver cancer are generally developing countries where access to health care is limited. For another, screening examinations for patients at risk for developing liver cancer are not available in these areas. In addition, patients from these regions may actually have more aggressive liver cancer disease. In other words, the tumor usually reaches an advanced stage and causes symptoms more 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.

There are no specific symptoms of liver cancer, and in fact, the earliest signs are usually subtle and can be mistaken for simple worsening of cirrhosis and liver function.Abdominal pain is uncommon with liver cancer and usually signifies a very large tumor or widespread involvement of the liver. Additionally, unexplained weight loss or unexplained fevers are warning signs of liver cancer in patients with cirrhosis. These symptoms are less common in individuals with liver cancer in the U.S. because these patients are usually diagnosed at an earlier stage. However, whenever the overall health of a patient with cirrhosis deteriorates, every effort should be made to look for liver cancer.

A common initial presentation of liver cancer in a patient with compensated cirrhosis (meaning that there are no complications of liver disease) is the sudden onset of a complication. For example, the sudden appearance of ascites (abdominal fluid and swelling), jaundice (yellow color of the skin), or muscle wasting without causative (precipitating) factors (for example, alcohol consumption) suggests the possibility of liver cancer. What’s more, the cancer can invade and block the portal vein (a large vein that brings blood to the liver from the intestine and spleen). When this happens, the blood will travel paths of less resistance, such as through esophageal veins. This causes increased pressure in these veins, which results in dilated (widened) veins called esophageal varices. The patient then is at risk for hemorrhage from the rupture of the varices into the gastrointestinal tract. Rarely, the cancer itself can rupture and bleed into the abdominal cavity, resulting in bloody ascites.

On physical examination, an enlarged, sometimes tender, liver is the most common finding. Liver cancers are very vascular (containing many blood vessels) tumors. Thus, increased amounts of blood feed into the hepatic artery (artery to the liver) and cause turbulent blood flow in the artery. The turbulence results in a distinct sound in the liver (hepatic bruit) that can be heard with a stethoscope in about one-quarter to one-half of patients with liver cancer. Any sign of advanced liver disease (for example, ascites, jaundice, or muscle wasting) means a poor prognosis. Rarely, a patient with liver cancer can become suddenly jaundiced when the tumor erodes into the bile duct. The jaundice occurs in this situation because both sloughing of the tumor into the duct and bleeding that clots in the duct can block the duct.

In advanced liver cancer, the tumor can spread locally to neighboring tissues or, through the blood vessels, elsewhere in the body (distant metastasis). Locally, liver cancer can invade the veins that drain the liver (hepatic veins). The tumor can then block these veins, which results in congestion of the liver. The congestion occurs because the blocked veins cannot drain the blood out of the liver. (Normally, the blood in the hepatic veins leaving the liver flows through the inferior vena cava, which is the largest vein that drains into the heart.) In African patients, the tumor frequently blocks the inferior vena cava. Blockage of either the hepatic veins or the inferior vena cava results in a very swollen liver and massive formation of ascites. In some patients, as previously mentioned, the tumor can invade the portal vein and lead to the rupture of esophageal varices.

Regarding distant metastases, liver cancer frequently spreads to the lungs, presumably by way of the bloodstream. Usually, patients do not have symptoms from the lung metastases, which are diagnosed by radiologic (X-ray) studies. Rarely, in very advanced cases, liver cancer can spread to the bone or brain. These are an infrequent problem in many patients who do not live long enough to develop these complications.

How is liver cancer diagnosed?

Blood tests

Liver cancer is not diagnosed by routine blood tests, including a standard panel of liver tests. This is why the diagnosis of liver cancer depends so much on the vigilance of the physician screening with a tumor marker (alpha-fetoprotein) in the blood and radiological imaging studies. Since most patients with liver cancer have associated liver disease (cirrhosis), their liver blood tests may not be normal to begin with. If these blood tests become abnormal or worsen due to liver cancer, this usually signifies extensive cancerous involvement of the liver. At that time, any medical or surgical treatment may be too late.

Sometimes, however, other abnormal blood tests can indicate the presence of liver cancer. Remember that each cell type in the body contains the full complement of genetic information. What differentiates one cell type from another is the particular set of genes that are turned on or off in that cell. When cells become cancerous, certain of the cell’s genes that were turned off may become turned on. Thus, in liver cancer, the cancerous liver cells may take on the characteristics of other types of cells. For example, liver cancer cells sometimes can produce hormones that are ordinarily produced in other body systems. These hormones then can cause certain abnormal blood tests, such as a high red blood count (erythrocytosis), low blood sugar (hypoglycemia) and high blood calcium (hypercalcemia).

Another abnormal blood test, high serumcholesterol (hypercholesterolemia), is seen in up to 10% of patients from Africa with liver cancer. The high cholesterol occurs because the liver cancer cells are not able to turn off (inhibit) their production of cholesterol. (Normal cells are able to turn off their production of cholesterol.)

There is no reliable or accurate screening blood test for liver cancer. The most widely used biochemical blood test isalpha-fetoprotein (AFP), which is a protein normally made by the immature liver cells in the fetus. At birth, infants have relatively high levels of AFP, which fall to normal adult levels by the first year of life. Also, pregnant women carrying babies with neural tube defects may have high levels of AFP. (A neural tube defect is an abnormal fetal brain or spinal cord that is caused by folic acid deficiency during pregnancy.)

In adults, high blood levels (over 500 nanograms/milliliter) of AFP are seen in only three situations:

Liver cancer

Germ cell tumors (cancer of the testes and ovaries)

Metastatic cancer in the liver (originating in other organs)

Several assays (tests) for measuring AFP are available. Generally, normal levels of AFP are below 10 ng/ml. Moderate levels of AFP (even almost up to 500 ng/ml) can be seen in patients with chronic hepatitis. Moreover, many patients with various types of acute and chronic liver diseases without documentable liver cancer can have mild or even moderate elevations of AFP.

The sensitivity of AFP for liver cancer is about 60%. In other words, an elevated AFP blood test is seen in about 60% of liver cancer patients. That leaves 40% of patients with liver cancer who have normal AFP levels. Therefore, a normal AFP does not exclude liver cancer. Also, as noted above, an abnormal AFP does not mean that a patient has liver cancer. It is important to note, however, that patients with cirrhosis and an abnormal AFP, despite having no documentable liver cancer, still are at very high risk of developing liver cancer. Thus, any patient with cirrhosis and an elevated AFP, particularly with steadily rising blood levels, will either most likely develop liver cancer or actually already have an undiscovered liver cancer.

An AFP greater than 500 ng/ml is very suggestive of liver cancer. In fact, the blood level of AFP loosely relates to (correlates with) the aggressiveness of the liver cancer. Finally, in patients with liver cancer and abnormal AFP levels, the AFP may be used as a marker of response to treatment. For example, an elevated AFP is expected to fall to normal in a patient whose liver cancer is successfully removed surgically (resected). People with higher AFP levels generally do not live as long as those with lower AFP levels.

There are a number of other liver cancer tumor markers that currently are research tools and not generally available. These include des-gamma-carboxyprothrombin (DCP), a variant of the gamma-glutamyltransferase enzymes, and variants of other enzymes (for example, alpha-L-fucosidase), which are produced by normal liver cells. (Enzymes are proteins that speed up biochemical reactions.) Potentially, these blood tests, used in conjunction with AFP, could be very helpful in diagnosing more cases of liver cancer than with AFP alone.

Imaging studies

Imaging studies play a very important role in the diagnosis of liver cancer. A good study can provide information as to the size of the tumor, the number of tumors, and whether the tumor has involved major blood vessels locally or spread outside of the liver. There are several types of studies, each having its merits and disadvantages. In practice, several studies combined often complement each other. On the other hand, a plain X-ray is not very helpful, and therefore, is not routinely done in the diagnostic work-up of liver cancer. Further, there is no practical role for nuclear medicine scans of the liver and spleen in the workup for liver cancer. Such scans are not very sensitive and they provide no additional information beyond that provided by the other (ultrasound, CT, and MRI) scans.

Ultrasound examination is usually the first study ordered if liver cancer is suspected in a patient. The accuracy of an ultrasound depends very much on the technician and radiologist who perform the study (operator dependent). Studies from Japan and Taiwan report that ultrasound is the most sensitive imaging study for diagnosing and characterizing liver cancer. But in these studies, highly experienced individuals performed the scans and spent up to one hour scanning each patient suspected of having liver cancer. An ultrasound has the advantages of not requiring intravenous contrast material and not involving radiation. Moreover, the price of an ultrasound is quite low as compared to the other types of scans.

Computerized axial tomography (CT scan) is a very common study used in the U.S. for the workup of tumors in the liver. The ideal CT study is a multi-phase, spiral CT scan using oral and intravenous contrast material. Pictures are taken in three phases:

Without intravenous contrast

With intravenous contrast (enhanced imaging) that highlights the arterial system (arterial phase)

When the contrast is in the venous phase

The pictures are taken at very frequent intervals (thin slices) as the body is moved through the CT scanner. Many radiologists use a specific protocol that determines how the contrast is infused in relation to how the pictures are taken. Therefore, CT is much less operator-dependent than is ultrasound. However, CT is considerably more expensive. Furthermore, CT requires the use of contrast material, which has the potential risks of an allergic reaction and adverse effects on kidney function.

There are several variations to CT scanning. For example, in a CT angiogram, which is a highly invasive (enters a part of the body) study, intravenous contrast is selectively infused through the hepatic artery (artery to the liver). The purpose is to highlight the vessels for better visualization of them by the CT scan. Also, in Japan, an oily contrast material called Lipiodol, which is selectively taken up by liver cancer cells, has been used with CT. The purpose of this approach is to improve the sensitivity of the scan. That is to say, the goal is to increase the percentage of abnormal CT scans in patients who have liver cancer.

Magnetic resonance imaging (MRI) can provide very clear images of the body. Its advantage over CT is that MRI can provide sectional views of the body in different planes. The technology has evolved to the point that the newer MRIs can actually reconstruct images of the biliary tree (bile ducts and gallbladder) and of the arteries and veins of the liver. (The biliary tree transports bile from the liver to the duodenum, the first part of the intestine.) MRI studies can be made even more sensitive by using intravenous contrast material (for example, gadolinium).

MRI scans are expensive and there is tremendous variability in the quality of the images. The quality depends on the age of the machine and the ability of the patients to hold their breath for up to 15 to 20 seconds at a time. Furthermore, many patients, because of claustrophobia, cannot tolerate being in the MRI scanner. However, the current open MRI scanners generally do not provide as high quality images as the closed scanners do. MRI sometimes finds lesions that are smaller than can be seen on a CT scan and can tell the radiologist more about the blood vessel (vascular) characteristics of the tumor; more importantly, there is no radiation risk, which becomes important if the screening test is to be repeated many times over a person’s lifetime.

Advances in ultrasound, CT, and MRI technology have almost eliminated the need for angiography. An angiography procedure involves inserting a catheter into the femoral artery (in the groin) through the aorta, and into the hepatic artery, the artery that supplies blood to the liver. Contrast material is then injected, and X-ray pictures of the arterial blood supply to the liver are taken. An angiogram of liver cancer shows a characteristic blush that is produced by newly formed abnormal small arteries that feed the tumor (neovascularization).

Another potential test used for many other cancers is a PET (positron emission tomography) scan, which involves the injection of radioactive sugar to light up actively growing cells, as in cancers. However, this is not very useful in liver cancer.

What, then, is the best imaging study for diagnosing liver cancer? There is no simple answer. Many factors need to be taken into consideration. For example, is the diagnosis of liver cancer known or is the scan being done for screening? What is the expertise of doctors in the patient’s area? What is the quality of the different scanners at a particular facility? Are there economic considerations? Does the patient have any other conditions that need to be considered, such as claustrophobia or kidney impairment? Does the patient have any hardware, for example, a pacemaker or metal prosthetic device? (The hardware would make doing an MRI impossible.)

If you live in Japan or Taiwan and have access to a radiologist or hepatologist with expertise in ultrasound, then it may be as good as a CT scan. Ultrasound is also the most practical (easier and cheaper) for regular screening (surveillance). In North America, a multiphase spiral CT scan is probably the most accurate type of scan. However, for patients with impaired renal function or who have access to a state-of-the-art MRI scanner, the MRI may be the diagnostic scan of choice. Finally, keep in mind that the technology of ultrasound, CT, and MRI is ever evolving with the development of better machines and the use of special contrast materials to further characterize the tumors.

Liver biopsy or aspiration

In theory, a definitive diagnosis of liver cancer is always based on microscopic (histological) confirmation. However, some liver cancers are well differentiated, which means they are made up of nearly fully developed, mature liver cells (hepatocytes). Therefore, these cancers can look very similar to non-cancerous liver tissue under a microscope. Moreover, not all pathologists are trained to recognize the subtle differences between well-differentiated liver cancer and normal liver tissue. Also, some pathologists can mistake liver cancer for adenocarcinoma in the liver. An adenocarcinoma is a different type of cancer, and as previously mentioned, it originates from outside of the liver. Most importantly, a metastatic adenocarcinoma would be treated differently from a primary liver cancer (liver cancer). Therefore, all of this considered, it is important that an expert liver pathologist review the tissue slides of liver tumors in questionable situations. New advances in immunohistochemistry (staining the microscopic cells with proteins that identify cell types very specifically) have helped to be able to tell the difference among cell and cancer types more reliably.

Tissue can be sampled with a very thin needle. This technique is called fine needle aspiration. When a larger needle is used to obtain a core of tissue, the technique is called a biopsy. Generally, radiologists, using ultrasound or CT scans to guide the placement of the needle, perform the biopsies or fine needle aspirations. The most common risk of the aspiration or biopsy is bleeding.