:: Care must be taken to avoid excessive sun exposure. It is specifically important to protect children and adolescents. For individuals who have a tendency to burn in the sun active protective measures must be taken throughout life.

Skin cancer is predominantly, but not exclusively, a disease of white skinned people. Its incidence, furthermore, is greatest where fair skinned peoples live at increased exposure to ultraviolet (UV) light, such as in Australia. Figure6 shows the marked latitudinal gradient in age-related incidence of melanoma, the form of skin cancer most likely to metastasise and cause death. The main environmental cause of skin cancers is sun exposure, and UV light is deemed to represent the component of the solar spectrum involved in skin cancer occurrence.

The type of sun exposure which causes skin cancer however appears to differ in the three main types. Squamous cell carcinoma shows the clearest relationship with cumulative sun exposure. This form of skin cancer is therefore most common in outdoor workers. The recipients of transplanted organs are particularly at risk of these tumours as a result of the combined effects of the unchecked growth of human papilloma virus (HPV) in their skin due to immunosuppression, and exposure to the sun. Basal cell carcinoma is the commonest type of skin cancer but it is the least serious as it is a local disease only. This form of skin cancer appears to share an aetiological relationship to sun exposure with melanoma.

The risk of cutaneous melanoma appears to be related to intermittent sun exposure. Examples of intermittent sun exposure are sunbathing activities and outdoor sport activities. Also, a history of sunburn has repeatedly been described as a risk factor for melanoma, which again is associated with intermittent sun exposure.

The incidence of melanoma has doubled in Europe between the 1960s and the 1990s and this is attributed to increased intense sun exposure, which has taken place this century. The incidence of squamous cell and of basal cell cancers has also increased in all European countries. Although much less life threatening than melanoma, these tumours represent 95% of all skin cancers, and their treatment amount to considerable costs for individuals and social security systems.

The advice to the European population must therefore be to moderate sun exposure: to reduce their total life-time exposure, and in particular to avoid extremes of sun exposure and sunburn. All Europeans however are not equally susceptible to skin cancer. The fairest are more susceptible, particularly those with red hair (but not exclusively), freckles and a tendency to burn in the sun.

The strongest phenotypic risk factor for melanoma however is the presence of large numbers of moles or melanocytic naevi, and twin study evidence is strong that the major determinant of naevus number is genetic with an added contribution from sun exposure. These naevi may be normal in appearance but are also usually accompanied by so-called atypical moles: moles which are larger than 5 mm in diameter with variable colour within and an irregular shape. The phenotype is described as atypical mole syndrome (AMS). The AMS is present in something like 2% of the north European population and is associated with an approximately ten times increased risk of melanoma. Advice about sun protection is therefore particularly of importance to this sector of the population. Some patients with the AMS report a family history, and overall a strong (three or more cases) family history is the greatest predictor of risk. These families should avoid the sun and should be referred to dermatologists for counselling.

The best protection from the summer sun is to stay out of it, but the following advice is given in order to allow safer enjoyment of the outdoors. Keeping out of the sun between 11 am and 3 pm is effective as UV exposure is greatest at this time. Therefore, scheduling outdoor activities for other times is important, particularly for children. Using shade is allied to this and clothing remains the second most important measure. Close weave heavy cotton affords good protection although the clothing industry is increasingly developing UV protective clothes with high sun protection properties, which are very valuable particularly where it is difficult to keep out of the sun.

Sunscreens are useful for protection against sunburns of skin sites such as the face and the ears. Sunscreen may protect against squamous cell carcinoma but there is currently inadequate evidence for their preventive effect against basal cell carcinoma and melanoma. However it is extremely important when using sunscreen to avoid prolongation of the duration of sun exposure that may be responsible for an increased risk of melanoma. Additionally, there is evidence that using higher SPF sunscreen prolongs further time spent in the sun. Great care should be taken when choosing to use sunscreen and also in the choice of SPF. In addition, sunbed use is also discouraged, as exposure to these devices resembles the type of sun exposure mostly associated with melanoma occurrence.