world cancer report - iarc
world cancer report - iarc
world cancer report - iarc
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
MELANOMA<br />
SUMMARY<br />
> Approximately 133,000 new cases of<br />
malignant melanoma are diagnosed<br />
<strong>world</strong>wide each year.<br />
> The risk of developing this highly malignant<br />
skin tumour varies markedly<br />
according to racial background (skin<br />
pigmentation) and geography (sunlightderived<br />
ultraviolet irradiation); highest<br />
incidence rates occur in white populations<br />
in Australia.<br />
> In Nordic countries, a steep increase in<br />
melanoma incidence has been attributed<br />
to excessive sun exposure during<br />
vacations in Southern countries.<br />
> Prognosis for patients with early-stage<br />
< 0.5 < 1.3 < 2.6 < 4.7 < 34.9<br />
melanoma is very good, while metastatic<br />
melanoma is largely resistant to cur-<br />
Age-standardized incidence/100,000 population<br />
rent therapies. Fig. 5.127 The global burden of melanoma of the skin in women. Incidence rates are high in North<br />
America, Europe, Australia and New Zealand.<br />
Definition<br />
Melanoma is a malignant proliferation of<br />
melanocytes, the pigment-forming cells of<br />
the skin, which is the site of most (>95%)<br />
disease.<br />
Epidemiology<br />
There are about 133,000 new cases of<br />
melanoma <strong>world</strong>wide each year, of which<br />
almost 80% are in North America, Europe,<br />
Australia and New Zealand. Incidence is<br />
similar in men and in women.<br />
Malignant melanoma of the skin occurs<br />
predominantly in white-skinned populations<br />
(“Caucasians”) living in countries<br />
where there is high intensity ultraviolet<br />
radiation but this malignancy afflicts to<br />
some degree all ethnic groups (Fig. 5.127).<br />
Assessed in relation to skin colour,<br />
melanoma incidence falls dramatically as<br />
skin pigmentation increases and the disease<br />
is very rare in dark skinned people.<br />
The highest incidence of melanoma<br />
occurs in Australia where the population<br />
is predominantly white, there is an average<br />
of six hours of bright sunlight every<br />
day of the year and there is an essentially<br />
outdoors lifestyle. The lifetime risk of<br />
developing melanoma in Australia is 4-5%<br />
in men and 3-4% in women.<br />
Dark-skinned people have a low risk of<br />
melanoma. In Africa and South America,<br />
the sole of the foot, where the skin is not<br />
pigmented, is the most frequent site<br />
affected in the context of a low incidence.<br />
Asian peoples have a low risk of<br />
melanoma despite their paler skins; naevi<br />
in Asian people, though common, are predominantly<br />
of the acral-lentiginous type<br />
which have low malignant potential.<br />
Marked increases in incidence and mortality<br />
are being observed in both sexes in<br />
many countries (e.g. Fig. 5.128), even<br />
where rates were formerly low, such as<br />
Japan. In the Nordic countries, for example,<br />
this averages some 30% every five<br />
years. Mortality rates are slightly higher in<br />
men than in women, with Australia and<br />
New Zealand registering rates of 4.8 and<br />
5.3 for men, and 2.5 and 3.2 for women,<br />
respectively [1].<br />
Etiology<br />
It is estimated that 80% of melanoma is<br />
caused by ultraviolet damage [2] to sensitive<br />
skin, i.e. skin that burns easily, fair or<br />
reddish skin, multiple freckles, skin that<br />
does not tan and develops naevi in<br />
response to early sunlight exposure.<br />
Prevention of melanoma is based on limitation<br />
of exposure to ultraviolet radiation,<br />
particularly in the first 20 years of life<br />
(Reduction of exposure to UV radiation,<br />
p141).<br />
Ultraviolet radiation is particularly hazardous<br />
when it involves sporadic intense<br />
exposure and sunburn. Most damage<br />
caused by sunlight occurs in childhood<br />
and adolescence, making this the most<br />
important target group for prevention programmes.<br />
Established but rare risk factors<br />
include congenital naevi, immunosuppression<br />
and excessive use of solaria. While<br />
melanoma may occur anywhere on the<br />
skin, the majority of melanoma in men is<br />
Melanoma<br />
253