world cancer report - iarc

LIVER CANCER
SUMMARY
> About 560,000 new cases of liver cancer,
usually hepatocellular carcinoma,
occur annually, and contribute significantly
to cancer mortality worldwide.
More than 80% of cases occur in Asia
and Africa and irrespective of etiology,
the incidence rate is more than twice as
high in men as in women.
> In Africa and Asia, hepatocellular carcinoma
is most frequently caused by hepatitis
B virus infection; concomitant
dietary exposure to aflatoxins multiplies
the risk. In Japan, this cancer is predominantly
caused by hepatitis C virus infection.
> In Western countries, liver cirrhosis due
to chronic alcohol abuse is the major
etiological factor.
> Hepatocellular carcinoma is almost
always lethal, survival from time of diagnosis
often being less than six months;
only 10% of patients survive five years or
more.
Definition
Hepatocellular carcinoma arises from
hepatocytes and accounts for 80% of all
primary cancers of the liver. Other tumour
types include intrahepatic cholangiocarcinoma
(tumours of that part of the bile
duct epithelium located within the liver),
hepatoblastoma (a malignant embryomal
tumour of childhood) and angiosarcoma
(arising from blood vessels) and are relatively
rare.
Epidemiology
Liver cancer ranks third amongst the
organ-specific causes of cancer-related
deaths in men worldwide and accounts for
almost 4% of all human cancers [1].
Globally, men are three times as likely as
women to be afflicted; liver cancer is the
fifth most common cancer among men
< 3.3
< 5.6
Fig. 5.37 Global burden of liver cancer in men. Note the high incidence rates in some African and Asian regions.
worldwide, but is the eighth in women.
Liver cancer is a major health problem in
developing countries where more than
80% of the world total (457,000 new annual
cases) occur. The highest incidence
rates are recorded in China (55% of the
world total), Japan, South East Asia and
sub-Saharan Africa (Fig. 5.37). In both
high and low incidence areas, there is
great variability in incidence among ethnic
groups [2].
Age-specific rates of incidence show
marked geographical variation (Fig. 5.38).
In the Gambia, age-specific rates peak in
the 45-55 years age range, whereas in
Europe and the USA, high risk is associated
with old age.
Time trends in liver cancer are difficult to
interpret due to changes in classification
and variable inclusion of metastatic
tumours [3]. However, the incidence of
hepatocellular carcinoma in Japan, the UK,
the USA and several Nordic countries has
increased noticeably over the past two
decades and has become progressively
associated with younger age groups [4].
Mortality rates have increased in several
< 9.0
< 15.0
Age-standardized incidence/100,000 population
< 98.9
regions, including France. Some of these
increases may be the result of improved
detection.
Etiology
Experimental evidence in a variety of in
vitro and animal models has demonstrated
the carcinogenic effects of hepatitis B
virus (HBV) on hepatocytes through both
direct and indirect mechanisms [5]. HBV
viral DNA has been found to integrate into
hepatocyte DNA and may serve as an
insertional mutagen. Viral replication in
infected cells and the concurrent host
immune response results in persistent
inflammation that may eventually
progress to cirrhosis and also may dispose
toward carcinogenesis; this is the
mechanism most commonly exhibited by
hepatitis C virus (HCV) (Chronic infections,
p56). Consistent epidemiological
data have associated a significant risk of
hepatocellular carcinoma with chronic
HBV infection, which accordingly has been
categorized as causing cancer in the context
of IARC Monograph evaluations [6].
Prevalence of carriers in developing coun-
Liver cancer 203