|
LIVER
CANCER
1. What
causes Liver Cancer?
Liver Cancer,
or Hepatocellular carcinoma
(Hepatoma) is one of the major
causes of cancer deaths worldwide
especially in Africa and East
Asia; it is the 4th commonest
cancer among males in Singapore.
Chronic hepatitis B (HBV) and
hepatitis C (HCV) infection,
ethanol, aflatoxins, hemochromatosis,
Wilson's disease and alpha1-antitrypsin
deficiency are risk factors
for hepatoma. They cause cirrhosis
that predisposes to development
of hepatoma.
2. What
are the symptoms of hepatoma?
Among asymptomatic
patient with risk factors such
as chronic HBV carrier, screening
has the best chance of detecting
small hepatoma and thus curative
resection.
Outside of screening program,
the presentation of hepatoma
is non-specific. The dominant
symptoms may be related to the
underlying cirrhosis eg. liver
function decompensation or complications
from portal hypertension such
as ascites or variceal bleeding.
Some patients may present with
vague abdominal discomfort,
unexplained weight loss or abdominal
mass. Occasionally, patients
can present with acute abdominal
pain from rupture of hepatoma.
In rare instances, metastatic
hepatoma to the brain, bone
or lung may be the initial presentation.
3. How
can hepatoma be detected?
Due to its
non-specific symptomatology,
diagnosis of hepatoma requires
a high index of suspicion. The
actual detection of hepatoma
relies on combination of identifying
common risk factors, serum tumor
marker (alpha-fetoprotein) and
the characteristic features
of the tumor on radiologic imagings.
In endemic
countries, the incidence of
chronic HBV infection among
patients with hepatoma can be
as high as 90%. 70-80% of hepatoma
has elevated serum alpha-fetoprotein.
Alpha-fetoprotein level of more
than 200ng/ml in the present
of a solid space-occupying lesion
in the liver is highly suggestive
of a hepatoma.
Ultrasound
scan is a very good screening
tool for mass lesion in the
liver in high risk patient.
It is inexpensive, non invasive
and readily available. However,
it is operator dependent and
lacks ability to provide a topographic
picture that is needed in planning
surgical intervention.
Contrast enhanced
triphasic computerized tomography
scan (CT scan) can provide high
quality images of the liver
and the tumor within it. Hepatoma
is typically a hypervascular
solid tumor with/without a clear
capsule in the background of
liver cirrhosis. The tendency
of the tumor to invade portal
veins and hepatic veins can
also be clearing see on the
CT scan. The added advantage
of CT images is ability in studying
the adjacent organs at the same
time.
Magnetic resonance
imaging (MRI) is a newer imaging
technology that does not involve
ionizing radiation. Its accuracy
in detecting hepatoma is similar
to CT scan but the cost is higher.
Characterizing
small tumors (those <2cm)
can be difficult on CT scan
or MRI especially when the tumor
marker is not elevated to diagnostic
level. In such cases, short
of doing a biopsy of the tumor,
lipoidol CT scan may add confidence
to the diagnosis of hepatoma.
This works on the principal
that hepatoma retains lipoidol
(an oil based contrast) after
injection through hepatic arteriography.
A non-contrast enhanced plain
CT scan is done 10 days to 2
weeks later, the retained lipoidol
in the heptoma will light up
brightly on the background of
non-enhanced uninvolved liver
parenchyma.
Hepatic artery
angiography may also demonstrate
the characteristic tumour blush
of hepatoma.
In majority of patients, the
diagnosis of hepatoma can be
reached confidently with the
combination of positive HBV
or HCV viral serology, raised
alph-fetoprotein and a CT scan
showing a characteristic space-occupying
lesion in the liver. Biopsy
of the tumor is usually not
necessary prior to surgical
resection. Biopsy of the tumor
is needed when the radiologic
features of lesions are atypical;
especially when the serology
and tumor markers are not also
supportive of the diagnosis;
in patient whose tumor is technically
unresectable or those who are
deemed not suitable for operation
due to other reasons.
Biopsy of
the tumor can be done percutaneously
under ultrasound or CT guidance;
or laparoscopically (with keyhole
operation). Core biopsy has
better yield than fine needle
aspiration but is associated
with small risk of tumor bleeding
and seeding along needle tract.
4.
Is there a cure for hepatoma?
Hepatoma is
one of the more aggressive malignant
tumor. The chance of cure is
related to the stage of the
tumor and the severity of the
underlying liver cirrhosis at
the time of diagnosis. A patient
with well preserved liver function
and a small size tumor (less
than 3cm) confined to one lobe
of the liver has a good chance
of cure after adequate resection
of the tumor.
Non-operative
treatments of HCC have a place
in non-resectable disease and
in patients who are poor surgical
candidates.
5. Principals
of surgical resection of hepatoma
Surgical resection,
when possible, remains the best
chance of cure in patients with
hepatoma. The objective of surgical
resection is to excise the tumor
with clear margin and at the
same time preserve as much normal
functioning liver as possible
to sustain life. This is a very
difficult balance to achieve
because of the often associated
underlying liver cirrhosis in
majority of patient with hepatoma.
In general, the prerequisites
for surgical resection are:
" Good
cardio-pulmonary fitness for
major operation
" No other serious medical
conditions
" Relatively well preserved
liver function - not jaundice,
no bleeding tendency, adequate
protein in the blood, no excessive
fluid in the abdomen and normal
cognitive state.
" Tumor confined to one
lobe of liver and without invasion
of major vessels in the liver
In order to
better select patients for surgical
resection, a specially dye clearance
test of the liver maybe necessary
prior to the operation. This
involves injection of the diluted
dye (Indocyanine green) into
a vein in your arm and collecting
blood sample from you at 5mins
interval for the next 20mins.
Poor clearance of the dye after
15minutes predicts poor outcome
following operation.
Surgical resection
of liver and liver tumor has
evolved to become a safe operation
with less than 5% surgical mortality.
This is largely due to better
understanding of the anatomy
and physiotherapy of the liver,
improvement in surgical techniques
as well as the advances in the
anesthesiology and surgical
care of patient after liver
surgery.
6.
What other treatment options
are available?
Liver transplantation remains
an option for patients with
hepatoma confined to the liver
but not suitable for resection
either due to poor liver function
reserve, multi-focal disease
or strategic location of the
tumor precluding safe resection.
Non-operative
treatment
In patients
deem not suitable for surgical
resection, several alternative
therapeutic option are available.
a. Transarterial
chemoembolization (TACE)
This is in
truth a dual treatment. It entails
performing a hepatic angiography
via the femoral artery in the
groin and selectively canulating
the feeding vessel/s to the
tumor and infusing combination
chemotherapy drugs mixed with
lipoidol (to increase tumor
uptake and retention of the
drugs) to the tumor; after which
the feeding vessel to the tumor
is embolised with gelfoam to
cause ischemic damage to the
tumor. This technique is suitable
for multiple lesions and bilobar
disease. Involvement of major
vascular structures is a relative
contraindication. This treatment
may need to be repeated 4-6
weeks later and several sessions
may be required. Side effects
and complications from TACE
are relatively few and minor.
b. Radiofrequency
ablation
This new modality
of treatment can be done percutaneously
with CT scan or ultrasound guidance;
it can also be done laparoscopically
under ultrasound guidance. The
treatment involves delivery
of radiofrequency wave to the
core of the tumor via a small
probe, this produces thermal
injury and ablation of the tumor.
It is suitable for lesions less
than 5cm in diameter. Tumors
in close proximity to a large
vessel are more difficult to
treat and there is higher risk
of rupture in tumor on the liver
surface during or following
RF treatment. These situations
require special consideration
when planning RF ablation.
c. Intra-tumoral
Ethanol Injection
This is a
relatively simple and expensive
treatment. This can be done
percutaneously under imaging
guidance and is effective for
small lesions less than 3cm
diameter. It is a good alternative
for patients with small tumor
(<3cm) but not suitable for
operation because of poor general
health or poor liver function
reserve. Intra-tumoral ethanol
injection can be administered
intra-operatively and is especially
useful in the situation of acute
tumor rupture. Contraindications
to treatment include renal insufficiency
and thrombosis of the main portal
vein.
d. Systemic
chemotherpay
Systemic therapies
with various chemo-agents either
alone or in combination regime
have been tried, they include
chemotherapy, immunotherapy
and hormonal therapy. The response
rate is generally poor and they
have not been successful in
improving overall survival nor
disease free survival.
7.
Conclusion
Liver
cirrhosis is the major predisposing
factor to development of hepatoma
and there are identifiable risk
factors for cirrhosis. Patient
at risk should have regular
screening and surveillance for
hepatoma. Diagnosis of hepatoma
requires combination of viral
serology, tumor marker and characteristic
features of tumor on contrast
enhanced CT scan or MRI. Surgery
remains the treatment of choice
for resectable lesion and long
term survival is good, especially
for small tumor. Orthotopic
liver transplantation is a possible
option for patients with end
stage liver cirrhosis and who
have low tumor load HCC confined
to the liver.
|
