Diagnostic
Tests For Liver CancerAfter the initial examination by the doctor, the
doctor likely will want to order a number of liver blood tests as well as some
imaging studies. This is necessary to confirm the suspicion of liver cancer and
to rule other diseases in or out. Here is a list of blood tests that often are
ordered by physicians who just examined a patient with a possible liver cancer.
The purpose of the tests is to establish the present liver function and whether
or not the constellation of the test results supports the diagnosis of liver cancer.
Other causes of liver disease are also ruled out such as pernicious anemia, which
is due to vitamin B-12 deficiency. The traditional liver function tests (transaminases
etc.) help to distinguish whether there is an obstruction of a biliary duct within
the liver, whether there is cirrhosis of the liver, hepatitis or normal liver
function.
| Blood tests for liver
cancer work-up | | Blood
test type: | Explanation
why test is done: | | CEA
(=carcinoembryonic antigen) | tumor marker
| | AFP (=alpha-fetoprotein) | tumor
marker | | PT(=prothrombin
time) and PTT(=partial thromboplastin time) | measures
blood clotting manufacturing capability of liver |
| B-12 level | rule
out pernicious anemia | | liver
function tests: transaminases,alkaline phosphatase, lactic dehydrogenase
| these liver enzymes show whether
they leak into the blood and if bile ducts are blocked |
| platelets and white blood cells | decreases
in these cells indicate portal hypertension (see text) |
| hepatitis A,B,C, and D |
look for cause of chronic hepatitis, cirrhosis and risk for liver cancer |
| other tests | depending
on clinical situation | With hepatitis present
a further test can determine whether it is hepatitis B or C, both of which have
a higher risk of causing liver cancer. Finally,
if platelets or white blood cell counts are decreased, this is usually a sign
that due to cirrhosis of the liver there is obstruction of the flow of blood from
the portal vein system and the pressure is increased in it. Such a condition will
lead to an enlargement of the spleen, called "hypersplenism". The enlarged
spleen filters out platelets and white blood cells and they are missing in the
blood stream, which is shown in the test. The most common reason for cirrhosis
of the liver is chronic alcohol abuse. The next common cause of cirrhosis of the
liver is chronic infection with hepatitis B or C. There are newer serological
tests that have been developed with the goal in mind to develop a similarly specific
and sensitive test for liver cancer as the PSA test is in the case of prostate
cancer. Radio-immuno-assays for alpha-fetoprotein (AFP) are a promising first
step. There are ethnic diffirences: 80%-90% are positive in Asian populations
with liver cancer , but only 60%-70% are positive in liver cancer patients in
the US and Europe. Other tests are more sensitive, but not specific enough. Only,
when some of these tests are combined with ultrasound investigations of the liver,
will the sensitivity and specificity reach 98% for liver cancer, not unlike in
prostate cancer, where the combination of rectal examination with a PSA blood
test is recommended for screening. Other diagnostic tests are done in the
imaging department of the hospital or the X-ray clinic. The
first such test is an ultrasound
of the abdomen, gallbladder and liver, which serves as an initial screening test.
If this shows an abnormality in the liver, a CT
scan of the liver is then ordered, which can be improved in resolution
with by injecting contrast material. A socalled angioportography,
where contrast material is injected into an artery called "superior mesenteric
artery" that supplies the liver with blood, shows minute detail of the liver
tissue and is very useful as a test to look for the exact extent of the cancer
within the liver tissue. It also shows any local metastases. Alternatively
an MRI scan can also be ordered instead. However, people who
have metal foreign bodies in them from prior injuries are not allowed to undergo
MRI scanning, but can have CT scans. In the past before CT and MRI scanning arteriograms
were done where the pathological tumor vessels were depicted and used as a diagnostic
test. Occasionally this test is still done in special circumstances such as when
a partial resection of the diseased liver is planned. A nuclear
medicine liver
scan is done with Technetium 99m sulfur colloid
in a hospital. A variation of this using a rotating gamma camera allows for better
imaging with spacial orientation, called single-photon-emission CT (=SPECT
scan). These tests are all very useful to "round up the cancer".
But all the physician knows so far is that there is a biochemical abnormality
on the blood tests and that there is a shadow on the various images of the imaging
tests. But there is no histological proof (meaning a cell test for proof
of the presence of liver cancer) at this point to indicate that indeed liver cancer
is present. As I pointed out in the other cancer chapters, cancer
is a histological diagnosis. For this reason a tissue sample has
to be taken and sent to the pathologist for a definite tissue diagnosis. This
is done by either a percutaneous liver biopsy, an open biopsy or a laparoscopic
biopsy. However, it is wise to do all the other tests mentioned above
first, as there could be profuse bleeding in a case where there is portal hypertension
and where the blood is thinned due to missing clotting factors. What approach
the physician will finally take to obtain tissue for a definite diagnosis of the
patient's condition depends to a large extent on these prior findings.
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