Malignant melanoma is the cancer of the skin in
which melanocytes develop into malignant cells.It accounts for about 4% of all
skin cancers but responsible for 80% of cancer related deaths in the US. Malignant
melanoma is the 6th common cancers among women and 5th
among men in the United States Of America it usually detected or diagnosed at
adult stage with a median age at the time of diagnosis being 58 years and only
0.9% of the cases before age of 20(1).
Its incidence increased rapidly in the 1970s at
about 6% per year. It has been estimated that the annual incidence increase is
about 3-7%. The increase in incidence rate has been attributed to screening
and early detection of malignant melanoma and awareness (2).
This type of
skin cancer is more common amongst the Caucasian population when compared to
the black people. People with light skin are at increased risk of developing
melanoma, about 17-25 times (1). Melanoma is reported to be more extremely rare the blacks
and most cases were acral lentiginous subtype (3, 4). Africans tend to have
protection form the carcinogenic effects of UV radiation than Caucasians due to
greater levels of melanin. The most common sites on which acral lentiginous
melanomas develop in Africans and African–Americans are nail beds, soles and
palms. In a retrospective analysis of melanoma in South Africans of mixed
ancestry showed histological type and anatomic distribution that is
characteristic of black populations, yet the 5-year survival rate in these
patients was similar to that seen in white populations (5).Annual increase in the incidence
rate of melanoma has been estimated to be 3–7% per year Caucasians (6).
In most cases malignant melanoma is diagnosed at
stage 3 or above, with a median survival of 6-9 months and 5 year survival rate
of less than 5% (7, 8).
The major predisposing factors are family history, exposure
to UV radiation, either intermittent or chronic exposure, fair skin, history of
melanoma. In a study done by Radespiel-Tröger, M., et al,
confirmed that there is an increased risk of melanoma in outdoor workers (9). Outdoor workers had more risk
behaviour with similar constitutional skin cancer risk factors: more UV
exposure (both occupational and leisure) and less sunscreen use and lower
health literacy). This results in higher exposure, more photodamage and an
increased risk of developing Basal Cell Carcinoma and Squamous Cell Carcinoma (10).
The high levels of sun exposure may be associated with with skin cancers in
people who work outdoor, together with insufficient use and practise of sun
protective measures when working outside(11). A large number of people are exposed
to varying levels of solar radiation at the workplace. In a study using the
CAREX (carcinogen exposure) database designed to provide selected exposure data
and documented estimates of the number of workers exposed to carcinogen by
country, reported that the most common occupational exposure to carcinogens in
the EU countries was solar radiation (12).