world cancer report - iarc

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