Naevi - patients with a strong family history of malignant melanoma and who have dysplastic naevi are at very high risk, but fortunately very few people fall into this category. Large numbers of benign and dysplastic naevi are highly significant risk factors, with risk directly proportional to the number of naevi. However, since the number of naevi increases with solar exposure, it is not known whether UV radiation promotes the change of naevi to melanoma or acts simply as an initiator by increasing the number of naevi.

Skin type - six skin types have been identified according to the ability of the skin to tan. People with skin types 1 and 2 are at greatest risk of developing malignant melanoma, whereas people with naturally occurring brown or black skin have a much lower risk as the presence of high amounts of melanin in their skin acts as a shield, blocking the transmission of UV radiation below 300nm. The presence of, and tendency to, freckle have also been identified as important risk factors.

Sunburn - tendency to sunburn and episodes of severe sunburn have been linked to melanoma. It has been suggested that sunburn in childhood may trigger melanoma later in life and studies of migrants to Australia suggest that early exposure is more important than exposure later in life. However, the relationship between sunburn and malignant melanoma is complex: remembered episodes of sunburn may signify generally high exposure to the sun or intermittent high exposure. Unlike skin type, which a person cannot change, exposure to the sun is a risk factor that can be modified and present knowledge would advocate avoidance of over-exposure, either over a short or long period.

Changes in an existing mole - to help people evaluate the importance of various changes in an existing mole, a 7-point checklist has been devised and is shown below. The aim of this code is to help promote earlier detection of melanoma, which can significantly increase survival. The 7-point code is intended both to increase public awareness of the signs, and thereby shorten delay in seeking medical advice, which is the main cause of delay in diagnosis, and also to ensure speedy and appropriate action by primary care doctors.

Seven point checklist for suspected malignant melanoma

o Major signs

If an existing mole gets larger or a new one is growing
If the mole has an irregular outline
If the colours are mixed shades of brown or black

o Minor signs

If the mole is bigger than the blunt end of a pencil
If it is inflamed or has a reddish edge
If it is bleeding, oozing or crusting
If it starts to feel different: for example, itching or painful

o Referral Guidelines

* One or more major signs - consider rapid referral

* Additional presence of one or more minor signs - increased possibility of melanoma

* Three or four minor signs without major sign - consider referral

Sunshine and Skin Cancer - Consensus Statement

1. That visible sunburn must be avoided by individuals of all ages.

2. That there is increasing evidence that excessive sun exposure and particularly sunburn when aged under 15 is a major risk factor for skin cancer in later life. Protection of the skin of children and adolescents is therefore particularly important.

3. That it is important to realise the cumulative nature of sun induced skin damage. This is of particular relevance to individuals now living in the UK who may have spent part of their lives in a tropical or sub-tropical environment.

4. That sun exposure giving rise to sunburn and subsequent skin damage can take place in the UK. It is therefore essential to protect the skin of both adults and children in this country, particularly during periods of sunny weather during the Spring and early Summer.

5. That individuals who develop skin cancer do not always have a history of deliberate sunbathing. Those who have an outdoor occupation and those who have an outdoor recreation, such as golfing, gardening, skiing or sailing, are also at risk and must learn to protect their skin.

6. A 4 point approach to minimising sun induced skin damage is advised. These are in descending order of importance.

• Avoiding noonday sun (between 11am and 3pm).
• Seeking natural shade in the form of trees or other shelter.
• The use of clothing as a sunscreen including T-shirts, long-sleeved shirts and hats.
• The use of broad spectrum sun screen with an SPFof 15 or higher to protect against UVB and with additional UVA protection.

7. There is no such thing as a safe or healthy tan. A tan is a sign that already damaged skin is trying to protect itself from further damage. The protecting power of a tan is weaker than that of a mild sunscreen of SPF2-4.

8. That in at least 4 out of 5 cases, skin cancer is a preventable disease.

Further information can be obtained from the Cancer Research Campaign web site at http://www.cancerresearchuk.org