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