Tests for liver cancer
Hepatocellular carcinoma (HCC or liver cancer) cannot be diagnosed by routine blood tests. There is only one specific blood test which can be used towards a diagnosis of HCC. This test specifically measures for the levels of the protein alfa-fetoprotein in serum (AFP).
Unfortunately only about half of all tumours will give a raised reading of AFP. So a normal AFP test does not exclude the presence of HCC. This is further complicated by the fact that AFP is also produced by proliferating liver cells so somebody with cirrhosis and liver regeneration is likely to have raised AFP levels already. As a consequence doctors will probably want to monitor whether the AFP levels are stable or not. Rising levels of AFP are more likely to indicate HCC.
Even where there is no detectable sign of HCC people with cirrhosis and an abnormal AFP still have a high risk of developing it. Anybody with cirrhosis and an elevated AFP, particularly with steadily rising AFP levels, will most likely either develop HCC or already have an undiscovered HCC.
There is no single imaging technique that will correctly identify all HCC's. Current techniques each have their strengths and weaknesses.
Ultrasound is usually the first screening test carried out if HCC is suspected. The accuracy of an ultrasound depends very much on the technician or radiologist who performs the scan. Some experienced operators may be able to detect lesions (areas of abnormal tissue) as small as 0.5cm. Others may only be able to identify much larger lesions. An ultrasound has the advantages of not involving ionizing radiation and intravenous contrast material (injecting a chemical into the body to improve the contrast of the imaging). The cost of ultrasound is also lower than other types of scans.
Computerised Tomography (CT) scans
When performed with an enhancing contrast agent CT scans can be just as sensitive as ultrasound. This is because the agent improves the imaging of the arterial and venous systems. CT scans are much less operator-dependent than ultrasound. They also have the advantage of being able to provide images of more areas of the body. CT scans are considerably more expensive than ultrasound and expose people to ionising radiation.
In this procedure a catheter is inserted into the hepatic artery and intravenous contrast material is injected into the liver. It may be useful for evaluating difficult lesions but it also involves ionizing radiation risks, arterial puncture and the administration of contrast agent. Hepatic angiography is usually carried out on people who are considered to be at high risk but who have failed to show any signs of HCC with other imaging studies. At the time of angiography, if a tumour is detected, it may be decided to block the artery feeding the tumour and before injecting anticancer drugs into it (chemoembolisation).
Magnetic Resonance Imaging (MRI)
MRI is becoming increasingly popular for the diagnosis of hepatic tumours. Like a CT scan it can examine large areas of the chest and abdomen in a single session. But because no ionizing radiation is involved the imaging can be repeated many times with little risk. The technology has evolved to the point that the newer MRIs can reconstruct images of the bile ducts, the gallbladder and of the arteries and veins of the liver. The use of intravenous contrast agents significantly increases the sensitivity of the procedure, but also increases the costs. MRI is currently expensive and availability of MRI machines is limited.
The only clear way to tell the difference between a malignant or benign growth is to examine it by removing a sample of tissue and reviewing it under a microscope. This process is called biopsy. A biopsy may be undertaken at the same time as an ultrasound or CT scan.
In this procedure a surgeon places an instrument called a laparoscope (a thin, flexible tube with a camera and light at the tip) into the body via a small cut in the abdomen. The laparoscope allows the surgeon to look directly at the liver to assess for signs of HCC.