The dangers of 'safe sun'

Are sunbathers really at risk of skin cancer? Or is it more that public health zealots try to turn anything pleasurable into a source of anxiety and fear? Dr Michael Fitzpatrick and Bríd Hehir throw some light on the subject

Health promotion around the link between exposure to sunlight and skin cancer has been gathering momentum over the past decade. In 1995 the Health Education Authority (HEA) launched its 'Sun know-how' campaign, followed up in 1996 with the slogan 'Shift to the shade'. The Australian advice 'slip, slap, slop' - slip on a shirt, slap on a hat, slop on some suncream - has been widely adopted as part of the sun awareness crusade in Britain. Schools have been a particular target as children are advised to play in shaded areas, wear Legionnaire-style hats and long-sleeved shirts. 'Molewatch' teams patrol beaches in seaside resorts, urging holidaymakers to cover up their dangerously exposed skin.

This year's promotion of the Solar UV Index is being spearheaded by the HEA, with posters, a new website, a video for schools and a factsheet, and supported by agencies such as the Imperial Cancer Research Fund and the Cancer Research Campaign (CRC). The idea is that people first classify their skin type (white, doesn't tan; white, tans easily; brown; black) and then calculate the duration of safe exposure according to the Solar UV Index announced in the weather forecast. According to Kate Law, CRC's head of clinical information, 'this is another great opportunity to educate and inform the public, on a daily basis, about how to practise safe sun'.

It is ironic that the sun, long regarded as a source of health and vitality, is now depicted as a mortal danger to the unsuspecting British public. It is even more ironic that the beginning of this year's skin cancer campaign coincided with the first recorded case of vitamin D deficiency in a white infant resulting from the use of high potency sunscreen creams (British Medical Journal (BMJ), 22 May). Three years ago the same journal noted reports that the use of sunscreens might increase the risk of some types of skin cancer (29 June 1996).

Leaving aside doubts about the efficacy or potential dangers of sunscreens, the relationship between sunlight and skin cancer is more complex - and more controversial - than would appear from the characteristically dogmatic pronouncements of the Health Education Authority and other agencies engaged in promoting the scare.

Though public anxieties are focused on malignant melanoma - moles which turn cancerous - in fact these are a relatively rare type of skin cancer, and the one least related to sunlight. Around 90 percent of skin cancers in Britain are either basal-cell or squamous-cell carcinomas: both are highly correlated with sun exposure and are commonest around the head, neck and arms, where the skin is most likely to burn. They characteristically appear in late middle-aged or elderly men (particularly if they are fair-skinned, and have worked outdoors in tropical climates). Fortunately, these cancers tend to grow slowly and are fairly easily treated with surgery or radiotherapy.

Malignant melanomas account for less than 10 percent of skin cancers, around 4000 cases a year in Britain (or about one case every 10 years for the average GP). These commonly arise in areas of the body not much exposed to the sun, such as the back of the legs, soles of the feet, scalp and buttocks. The incidence is similar in Japan, where there is little tradition of sunbathing. Some cases have a family history of melanoma, suggesting a genetic contribution. Malignant melanomas can appear at any age, but are most common in young adults. Though if diagnosed early and treated aggressively, most are curable, some cases are highly malignant and spread early to other parts of the body, resulting in a significant mortality rate (around 1500 deaths a year).

Though it is commonly asserted that there is an 'epidemic' of skin cancer in general and malignant melanoma in particular, this is contentious. According to Newcastle professor of dermatology Sam Shuster, the dramatic increase in the number of 'suspicious' moles removed and sent for microscopic examination over the past decade has been paralleled by a tendency to reclassify benign disease as malignant: 'instead of allowing biopsy detection of early, curable disease, the minimal changes we once accepted as benign from experience of their subsequent behaviour are now being called early malignancy.' (BMJ, 18 July 1992) His conclusion is that 'melanomas are being invented, not found', and that the resulting 'spurious cures' are being 'used to justify an incompetent and frightening screening programme'.

Shuster is critical of health promotion advice to regard moles and other minor skin lesions which change in size or pigmentation, itch or bleed, as potentially malignant (BMJ, 7 September 1996). Though such features are not 'usefully predictive' of melanoma, he complains that 'these common events have been used to frighten thousands of patients to their general practitioner'. The result of what he characterises as 'an ill-conceived propaganda exercise' is that dermatology clinics have been swamped by anxious patients with harmless moles, delaying the treatment of those with malignant conditions.

Surveying the incidence of malignant melanoma in different countries in recent years, and the relationship between the microscopic appearance of the cancer cells and the pattern of disease in individual cases, Professor Jonathan Rees, a colleague of Shuster's in Newcastle, concludes that 'there is after all no robust empirical evidence to defend most health promotion in this area' (BMJ, 20 January 1996). According to another dermatologist, PN Karnauchow, 'the simplistic idea of a sun/melanoma relationship is based more on belief than on science' (Lancet, 30 September 1995).

The grave doubts expressed by eminent medical authorities about every aspect of the link between sunlight and skin cancer appear to have no effect whatsoever on the great 'safe sun' crusade. So why, despite the lack of scientific evidence, has this campaign had such a major social impact?

No doubt there is an element of opportunism among dermatologists (and manufacturers of sunscreens) keen to raise awareness of skin cancer. Shuster and Rees have provoked considerable controversy with their accusation that some of their academic colleagues are 'making a living out of perpetuating the skin cancer scare' (Sunday Times, 24 August 1997).

The disproportionate focus on melanoma clearly reflects the priorities of health promotion activists, who have an instinctive affinity for the drama of a malignant condition that mainly affects young people, irrespective of its rarity and the limited scope for prevention. Though malignant melanoma may be rare, moles are very common and sunbathing very popular: there is therefore enormous scope for the sort of scaremongering that is dignified as health education and public information. The threat to children is always a particularly welcome angle for health promotion activists, for whom encouraging parental guilt is a key strategic device.

The central role of the public health minister at the launch of this year's skin cancer campaign reflects the continuing appeal of health scares for politicians. The previous Tory government went so far as to set targets for reducing the incidence of malignant melanoma in its comprehensive 'Health of the nation' programme: given what we have seen about the artificiality of such figures, meeting such targets would be of dubious value. Nevertheless, for politicians lacking in public prestige, such gestures project an image of concern about health and disease. Initiatives which enhance the professional regulation of individual behaviour are always welcomed by governments - and never more so than by New Labour.

The media play a significant, if subordinate, part in increasing the impact of health scares. The HEA was delighted to announce last month that its Solar UV Index campaign had been 'adopted with great enthusiasm by the BBC, ITV, Sky, national newspapers and all other media'. The enthusiasm of the media executives reflects their recognition of the popular resonance for health stories as well as their readiness to serve the agendas of the professionals and the politicians.

Meanwhile, down on the beaches and in the parks and gardens of the nation, there seems a remarkable readiness to accept the dictates of the safe sun crusaders. Though a hard core of leathery sun worshippers remain committed to their tanning rituals, most people have cut down on their exposure or use more sunscreens. Few parents would now allow a child out in the sun without protection - to do so would be to risk public rebuke if not a report to the NSPCC.

The dangers of what Professor Shuster calls 'disaster dermatology' are considerable. The 'worried well' waste much of their own time and energy as well as burdening GP surgeries and skin clinics. They tend to overprotect their children, with much greater danger to their personal and emotional development than the risk of developing rickets. Meanwhile, the occasional pleasure of sunbathing in Britain is spoiled by anxieties about diseases, if not by 'molewatch' vigilantes in person. By the time you have looked up the day's Solar UV index, factored in your skin type, calculated your exposure time and selected the appropriate Sun Protection Factor sunscreen, it might well have started raining.