Comment

The evidence from RCTs suggests that vitamin A and beta-carotene are not effective for the prevention of skin cancers. The evidence for the effect of isotretinoin is equivocal and there is no evidence that brewer's yeast tablets have a preventive effect for NMSCs. There is some evidence from one case-control study that long-term use of oral contraceptives may be associated with increased risk of melanoma.

Early detection and diagnosis are generally accepted as the most effective secondary prevention intervention likely to reduce the morbidity and mortality for skin cancer. Melanoma survival rates are linked to early diagnosis and treatment and especially to the thickness of the tumour (Breslow thickness). Patients with thin tumours (less than 1-5 mm) have a 5-year survival rate in excess of 90% compared with a survival rate of 68% for tumours greater than 3 mm in thickness. The major determinant of delay in excising such tumours is delay in seeking advice.33

Self-examination for skin pigmentary characteristics associated with melanoma, for example freckling, may be a useful way to identify individuals at increased risk of developing melanoma. Skin type, the propensity to burn after sun exposure, and tanning ability, alone or with other physical characteristics such as hair colour, has been used as a measure of sun sensitivity in epidemiology studies.34,35

Other interventions for early detection and diagnosis involve primary-care practitioners and dermatology clinics, and an early study revealed the problems with such a policy. The work overload on dermatology clinics in particular was a major outcome of the Cancer Research Campaign's Mole Watcher seven-centre study.36 This has implications for policy planners. A recent population cross-sectional study of 1600 participants aged 25-69 years and stratified by a social deprivation score of wards within one general practice in the UK looked at the feasibility of targeted early detection for melanoma using a postal questionnaire and an invitation to screening by a consultant dermatologist. Participants were randomly selected from a population of 8000. A total of 1227 (77%) returned the questionnaire and 896 (56%) attended the screening clinic. Uptake was lower for men (P<0-001) and skin types 3 and 4 (men only, P<0-001). Twenty per cent of women and 10% of men felt nervous about attending the clinic but only 4% were worried by the

Can early detection, diagnosis and treatment reduce the risk of skin cancer and melanoma?

questionnaire. The level of agreement between self-assessment and the dermatologist's assessments of risk factors was best for hair colour (k 0-67; sensitivity 73%; specificity, 98%). People tended to underreport their level of risk. Over 95% knew about at least one major sign of skin cancer, with 54% reporting incorrect signs of melanoma.37-41

A recent study in Leicestershire, UK, examined the effect of the introduction of a pigmented lesion clinic on the referral interval for patients with melanoma presenting to their general practitioner.42 There was a significant initial reduction in the mean referral interval following the introduction of the clinic from 27-9 days (SEM -6-6) in 1984 to 11-3 (2-3) days in1987 (P<0-01). This was not maintained over the following 7 years and rose to a mean of 20-4 (4-4) days in 1994. This was not significantly better than the 1985/1986 level. The rise was the result of melanomas being referred directly to other clinics. By 1994 only 48% of melanomas were being referred to the pigmented lesion clinics, compared with 70% in 1987, with more than 50% of melanomas being correctly diagnosed by general practitioners.

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Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.

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