Melanoma is the medical term that describes 'any of several types of skin tumours characterised by the malignant growth of melanocytes' (dictionary.com). The word derives from the ancient Greek word melas meaning 'black' and literally means a tumour containing melanin.
Melanoma is one of three types of cancer that affect the skin; the other two are called Squamous Cell Carcinoma and Basal Cell Carcinoma.
Although melanoma is in fact the least common of the three types, it is the most serious due to its ability to spread to other parts of the body.
Melanocytes are pigment cells that produce melanin, which protects the skin from damage caused by sunlight (UV radiation). Melanocytes often clump together as the body is growing to form moles. Moles are not cancerous in themselves, however if the cells in the mole start to grow and divide more rapidly than normal, this can cause a melanoma which either grows up or down into skin layers below. If untreated a melanoma can spread rapidly into the dermis (lower skin layer) and then spread to other parts of the body via the bloodstream or lymphatic system.
Even though the main cause of melanoma is overexposure to sunlight (or other sources of UV radiation like sun beds), melanoma can form anywhere on skin, including areas that are not normally exposed to the sun such as inside the mouth or on the soles of the feet. It's common for men to develop melanoma on the back, whereas women are more likely to develop melanoma on their legs.
According to the Cancer Council of Australia, there is a 1 in 14 chance of being diagnosed with melanoma by the age of 85 for men and a 1 in 24 chance for women. It is the fourth most common cancer diagnosed in Australia (which with New Zealand has the highest incidence of melanoma in the world). Melanoma is the sixth most common cause of cancer death for men and the tenth most common for women in Australia.
The following are regarded as risk factors for the development of melanoma:
- Family history of melanoma (in a close relative)
- Fair skin, light eye / hair colour, freckles
- High mole count (especially unusual moles, known as 'Dyplastic Neavi')
- Tendency to burn in the sun, not tan
- Depressed immune system
- Previous skin cancer
- History of repeated sunburn, especially at a young age (before age 15)
- High exposure to sunlight/UV radiation (including solariums and sun beds) *
- Age (melanoma is most commonly diagnosed in people over 50)
* People who use sun beds and solariums before age 35 have an 87% greater risk of developing melanoma than the rest of the population.
How is melanoma diagnosed?
There are generally no symptoms as such, so melanoma is diagnosed by reference to changes that occur in a mole. The abbreviation to describe these changes is 'ABCDE', which stands for:
- A – Asymmetry (i.e. irregular in shape)
- B – Border which is uneven
- C – Colour which is uneven
- D – Diameter (i.e. more than 6mm)
- E – Evolving (i.e. change, growth and elevation)
Prevention of melanoma
The most effective form of prevention is to stay out of the sun, especially in the middle of the day, and protecting the skin with sunscreen, clothes and a hat when outside, even on cloudy days.
It's also strongly advisable to have annual skin checks with a dermatologist (skin specialist) to monitor new and existing moles.
If detection is at any early stage, melanoma can be very effectively treated. The most effective treatment of melanoma is surgical removal of the mole and some of the surrounding skin.