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Melanoma

What is Melanoma?

Melanoma is a skin cancer that arises from the pigmented forming cells in the skin called melanocytes. The majority form from excessive sun exposure. Less than half of melanomas arise from moles while the majority arises on normal appearing skin. Melanoma is the most dangerous of the common types of skin cancer.

What does melanoma look like?

Melanoma usually appears as an enlarging coloured skin spot. They can have various shades of brown, black and blue. They can be flat or raised. A small proportion of melanoma are not colourful, but appear as a changing "skin coloured" spot. Because of this, any changing skin spot should be reported to your doctor. Remember that the majority of melanoma have no symptoms when they are found. Some may be itchy, and bleeding is a late sign. Melanoma, like other skin cancers, are only very rarely irritating to the touch. In the majority of cases they are detected solely by their appearance.

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How important is early detection?

It is very important to remove a melanoma early in its life. This is because "thin" melanoma have a very good prognosis (96% cure rates). Therefore early detection is vital in controlling the disease (see section on "checking your own moles"). The commonest site for melanoma in men is the back and in women the legs. However, you should check all of your skin.

What type of person has a high risk of developing melanoma?

The most important common risk factor for developing melanoma is having lots of moles. Other important risk factors include a family history of melanoma, a personal history of melanoma or other types of skin cancer, freckled or fair skin (skin that tends to burn rather than tan), and frequent recreational sun exposure. While melanoma can occur in childhood it is uncommon before puberty. Melanoma is also uncommon in the Aboriginal, Asian and African races.

How are melanomas on the skin treated?

The standard treatment for melanoma on the skin is surgical excision. The extent of the scar required to adequately remove the melanoma depends mainly on the thickness of the melanoma. Most excisions leave non-disfiguring linear (straight line) scars. However, this also depends on the site of the melanoma.

Sun exposure and Melanoma

Exposure to sunlight (ultraviolet light) is the primary cause of most melanoma on the skin. However, at the present time it is unclear which of the components of ultraviolet light (UVB, UVA or both) are the most important for causing melanoma.

What type of sun exposure causes melanoma?

Many studies have confirmed that intermittent sun exposure (as in recreational sun) and episodes of sunburn increase the risk for developing melanoma. So short bursts of unprotected intense sun exposure should be avoided. It is unclear in childhood whether it is the intermittent pattern as seen with studies in adults or a greater total amount of sun exposure that causes greater risk of melanoma. However, it seems that exposure in childhood and adolescence is more potent in causing melanoma than in adult life.

What time of the day should I avoid prolonged unprotected sun exposure?

Peak UV periods occur in Australia between 11am-3pm during daylight savings months and 10am-2pm in standard time.

How much sun exposure do I need for vitamin D production?

UVB radiation from sunlight exposure on the skin is responsible for the majority of Vitamin D in people who do not take vitamin D supplements. This is because most natural foods contain little vitamin D. Infants obtain vitamin D from the placenta (therefore depends on the mother’s vitamin D levels), while breast milk has little Vitamin D. The amount of sun exposure required to get adequate vitamin D levels depends on skin type (the fairer your skin the less you need), age (more time in the elderly), latitude, season, time of the day and cloud cover. Daily exposure to as little as one-third of a sunburning dose to 15% of your body surface (hands, arms and face; or legs) can produce significant amounts of vitamin D. For fair skin people (those that tend to burn rather than tan) this can be achieved around 6-8 minutes just before 10am or just after 2pm (standard time) in summer in most of Australia but in winter takes around 30-50 minutes in southern parts of Australia but still under 10 minutes in the north. Correctly applied sunscreens can reduce vitamin D production but with real-life use this does not seem to be a problem .

Do sunscreens protect against melanoma formation?

Sunscreens have been shown to reduce sun spots (actinic keratoses) and squamous cell carcinoma. Yet, when all studies are evaluated together, no reduction of the incidence of melanoma with sunscreen use has been shown. However, sunscreens are used to prolong intentional sun exposure, tend to be used by people at higher risk of melanoma and the studies did not assess the sun protection factors (SPF) or correct application of sunscreens. Furthermore, the incidence of melanoma among young adults in Australia fell from 1983 to 1996, coinciding with strong public health messages to use sun protection. For these reasons it is recommended to use sunscreens to accompany rather than replace physical protection (shade, hats, clothing).

Do sunbeds (solaria) cause an increase risk for developing melanoma?

Solaria lamps emit UVA rather than UVB. As stated above we do not know which of these components are most important in causing melanoma. When examining all of the studies assessing sunbed use and melanoma risk there was a minor increase in risk in those people using sunbeds. The risk was greater if sunbeds were used before 35 years of age. It should be understood that these studies suffer from not being able to take into account many confounding factors. Hence, strong conclusions on the risks of sunbed use are currently not able to be made. Finally, unlike sun exposure, solaria exposure does not induce Vitamin D production.

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