Melanoma is a cancer of the skin which develops from the cell which produces our skin colour or pigment. That cell is the melanocyte. The melanocyte sits within the scaly top layer of the skin (the epidermis) manufacturing pigment and injecting the pigment into the nearby skin cells (keratinocytes). The number of melanocytes that we all have is pretty similar but humans vary in the type of pigment produced and how that pigment is distributed in the skin cells. The nature and distribution of the pigment determines our skin colour and how vulnerable the skin is to sun burn. This is important as the evidence is that sunburn and damage resulting from burning is what leads to genetic changes (mutations) in the melanocytes which ultimately lead to the development of melanomas.
Epidemiological research has shown that melanoma has become steadily more common in pale skinned populations since the early part of the 20th century but the increase in the last 10 years has been especially dramatic and particularly in people 60 years older and male. Melanoma however occurs in all age groups after puberty and in most pale skinned populations the incidence continues to increase at all ages. Epidemiological studies have also shown that the type of sun exposure which increases melanoma risk is intermittent: the sort many people have on holiday. Holiday sun exposure is often intense, with exposure of previously very pale skin to sudden high doses of sunlight, causing reddening of the skin. Interestingly, sun exposure which occurs continuously as for example in outdoor workers, does not seem to be associated with melanoma risk. It is thought that the increased incidence of melanoma in pale skinned people has occurred because pale skinned people in developed countries increasingly have the opportunity for sunny holidays.
The international melanoma genetics consortium GenoMEL (www.genomel.org) has carried out research to identify inherited genetic variation which increases risk of melanoma, and on their website there are summaries of the results of that research. The research published by GenoMEL has identified inherited genes which increase melanoma risk which are pigment genes (affecting skin colour and vulnerability to sunburn), genes which are associated with having more moles (melanocytic naevi) and others associated with a part of the genetic makeup of the cell called the telomere. The genetic makeup of the cell or DNA is often described as the blueprint the cell uses to function, grow and divide. The DNA is organised into chromosomes and telomeres are found at the end of chromosomes. A scientist called Elizabeth Blackburn received the Nobel Prize for her work on telomeres.
Watch the video below describing her work and the function of telomeres.