|
 |
Download PDF Version of this Article
Bookmark this Site
|
|
Archived Issues of Radiology Rounds
MGH Department of Radiology Website
|
|
Screening for Hepatocellular Cancer in Cirrhotic Patients
|
|
- Patients with cirrhosis have an annual risk of 1-6% of developing hepatocellular cancer (HCC);
- Liver transplantation is an effective treatment and, therefore, it is justifiable to screen patients at
high risk for developing HCC every 6-12 months;
- Ultrasound imaging and monitoring blood concentrations of alpha-fetoprotein are recommended
for screening;
- If ultrasound images detect a lesion, or if the liver echotexture is heterogeneous because of
severe cirrhosis, MRI is recommended for further evaluation
|
The
incidence of hepatocellular carcinoma (HCC) has increased dramatically
in the United States within recent decades and it is now the fourth
leading cause of cancer-related deaths worldwide. The increase has been
driven mainly by the epidemic of hepatitis C infection - persons with
HCV cirrhosis have about a 20% lifetime risk of developing HCC.
However, all etiologies of cirrhosis increase the risk and patients
with cirrhosis have an annual risk of 1-6% of developing HCC.
Non-alcoholic steatohepatitis, which is associated with type II
diabetes and obesity, also appears to be associated with an increased
risk for developing HCC. However, about 90% of all cases are found in
patients who are cirrhotic and, in the USA, HCC is most commonly found
in men aged 45-65.
If HCC is detected early, when
there is a single tumor less than 5 cm or no more than three tumors
less than 3 cm and the disease is intrahepatic, it can be treated
successfully with liver transplantation. The survival rate after
transplantation approaches that for patients who undergo transplants
for reasons other than cancer. Alternatively, patients can be treated
by surgical resection with partial hepatectomy or by ablation in situ (see Percutaneous Radiofrequency Ablation of Tumors in the Liver and Kidney, Radiology Rounds, September 2004). However, if the diseased liver is not completely removed, the patient is at high risk for developing another tumor.
Unfortunately, many patients with HCC are not diagnosed until the
disease is advanced and not treatable, when the median survival time
after diagnosis is 6-20 months. Therefore, there is considerable
interest in screening high-risk patients for HCC in order to detect
early stage disease that is amenable to treatment. However, at this
time there is no good evidence to show that early detection increases
long-term survival. In addition, it is not clear how to optimally
screen at risk patients for HCC based on current evidence.
|
|
|
|
| |
|
Transverse and sagittal ultrasound images show an HCC in a cirrhotic liver.
|
Screening Methods
Screening for HCC is most commonly conducted every 6-12 months in
patients at risk by measuring of blood alpha-fetoprotein (AFP)
concentrations and ultrasonography. The sensitivity and specificity of
AFP screening varies with the level of AFP selected and the risk of HCC
in the population selected. Overall, neither the sensitivity nor the
specificity is high and the positive predictive value varies from 9-50%.
Reports of the sensitivity of ultrasound have varied widely, ranging
from 20-58%. Many of the higher estimates of sensitivity have come from
Asia, where patients are slimmer than those in the USA. Since the
quality of ultrasound images is degraded at greater depths of tissue,
the sensitivity of ultrasound in overweight patients is relatively
poor. In addition, the difficulty in detecting HCC lesions in
ultrasound images of livers that have gross abnormalities due to
cirrhosis decreases sensitivity. In studies in which explanted severely
cirrhotic livers were examined after liver transplantation, the
sensitivity has been reported to be as low as 20% for 2-3 cm lesions
and 13% for 1-2 cm lesions. Nevertheless, the specificity for
detecting HCC with ultrasound is high (92-96%) and the sensitivity
improves with lesion size.
|
|
|
|
|
|
Sensitivity |
Specificity |
Positive Predictive Value |
| Alpha-fetoprotein >20 ng/ml |
39-65% |
76-94% |
9-50% |
| Ultrasound |
20-58% |
92-96% |
69-78% |
| CT |
54-85% |
66-96% |
67-87% |
| MRI |
55-88% |
57-86% |
88-91% |
Note: The values for the imaging biomarkers are those for per lesion sensitivity and specificity
|
|
|
|
|
| |
|
In same patient, Gadolinium contrast MR image shows transient enhancement of the tumor during the arterial phase.
|
|
Detecting HCC with MRI and CT
|
|
Recommendations
|
| Both
MRI and CT can detect HCC with a higher sensitivity than ultrasound but
these imaging methods also detect other focal abnormalities and about
10% of findings are false negatives. In both cases dynamic imaging
using a contrast agent is necessary to detect the tumors, which are
highly vascularized with an arterial, as opposed to portal, blood
supply. The tumors are, therefore detected as a transient enhancement
as the contrast agent passes though the arterial blood vessels. The
sensitivity of MRI appears to be somewhat higher than CT but neither
technique has high sensitivity for detecting lesions <1 cm. However,
it has been shown that about 50% of lesions that are <1.5 cm do not
develop into HCC and are not apparent on images acquired at follow-up
after 12 months. |
|
Although
there is insufficient evidence to clearly demonstrate that screening
for HCC is beneficial for patients, the existence of an effective
curative treatment (liver transplantation) justifies screening
cirrhotic patients who are at increased risk. Ultrasound is the least
sensitive of the imaging modalities for the detection of HCC but, due
to constraints of cost and resource availability, neither MRI nor CT is
suitable as a routine screening method. Therefore, ultrasound imaging
should be the initial screening method, together with monitoring blood
concentration of alpha-fetoprotein. If the ultrasound examination shows
a normal liver, additional imaging is unlikely to find HCC.
However, if the ultrasound images are abnormal, either because the
liver has a heterogeneous appearance due to cirrhosis or because a
lesion is detected by ultrasound, contrast-enhanced MRI or CT is
recommended for further evaluation of the patient.
|
Scheduling
|
|
Further Information
|
|
Ultrasound
screening of patients at high risk of developing HCC is performed at
Mass General West Imaging in Waltham, Mass General Imaging in Chelsea,
or in the Yawkey Center on the main MGH campus. Appointments can be
scheduled by calling 4-XRAY (617-724-9729) or through the web-based
Radiology Order Entry system, http://mghroe
.
|
|
For further questions, please call Peter Hahn, M.D.
, Associate Radiologist, Abdominal Imaging and Intervention Division, at 617-726-8396.
We would like to thank Raymond Chung, M.D.
, MGH Gastrointestinal Unit, for his advice and assistance in the preparation of this article.
This article provided useful information about the appropriate use of imaging studies:
Note: clicking one of these options will close this window.
|
|
References
|
|
|
|
National Cancer Institute: Hepatocellular Cancer (PDQ®): Screening
Di Bisceglie, AM. (2004) Issues in screening and surveillance for hepatocellular carcinoma. Gastroenterology 127: 7
El-Serag, HB. (2004) Hepatocellular carcinoma: recent trends in the United States. Gastroenterology 127: 34
|
|
Fung, KT, Li, FT, Raimondo, ML, Maudgil, D, et al. (2004) Systematic review of radiological imaging for hepatocellular carcinoma in cirrhotic patients. Br J Radiol 77: 633-40
Talwalkar, JA and Gores, GJ. (2004) Diagnosis and staging of hepatocellular carcinoma. Gastroenterology 127: S126-32
|
|
|
|
|
|
|
|
