Article

Prolonged prevention of squamous cell carcinoma of the skin by regular sunscreen use

School of Population Health, University of Queensland, Brisbane, Queensland 4029, Australia.
Cancer Epidemiology Biomarkers & Prevention (Impact Factor: 4.32). 01/2007; 15(12):2546-8. DOI: 10.1158/1055-9965.EPI-06-0352
Source: PubMed

ABSTRACT Half of all cancers in the United States are skin cancers. We have previously shown in a 4.5-year randomized controlled trial in an Australian community that squamous cell carcinomas (SCC) but not basal cell carcinomas (BCC) can be prevented by regular sunscreen application to the head, neck, hands, and forearms. Since cessation of the trial, we have followed participants for a further 8 years to evaluate possible latency of preventive effect on BCCs and SCCs. After prolonged follow-up, BCC tumor rates tended to decrease but not significantly in people formerly randomized to daily sunscreen use compared with those not applying sunscreen daily. By contrast, corresponding SCC tumor rates were significantly decreased by almost 40% during the entire follow-up period (rate ratio, 0.62; 95% confidence interval, 0.38-0.99). Regular application of sunscreen has prolonged preventive effects on SCC but with no clear benefit in reducing BCC.

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    • "Sunscreen use is widely advocated by public health bodies as a means of reducing the risk of skin cancer, especially in sun-sensitive skin types I and II. However, there is no evidence that sunscreens prevent malignant melanoma (MM) [10], some evidence that they may prevent basal cell carcinoma (BCC) [11], but there is good evidence that they prevent squamous cell carcinoma (SCC) [11]. Sunscreens would be expected to offer some protection against SCC because the action spectrum for this lesion, based on mouse data, is quite similar to that for human erythema. "
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    ABSTRACT: The adverse effects of solar ultraviolet radiation on the skin are well documented, especially in fair-skinned people. These can be ameliorated by photoprotection strategies advocated by many public health bodies and typically include sun avoidance, sunscreen use and clothing. The UVB waveband which is the main cause of all adverse effects investigated in the laboratory to date is also the waveband for vitamin D photosynthesis which is the only established benefit of solar exposure. This is especially important because solar UVB is the main source of vitamin D for most people. There is increasing evidence that vitamin D plays a much greater role in human health than was previously thought. This has given rise to concerns that photoprotection, especially sunscreen use, could adversely affect vitamin D status and human health. Furthermore, it is stated that people with heavily pigmented skins often have poor vitamin D status because of photoprotection by melanin. In this paper we review the effect of photoprotection strategies and pigmentation on vitamin D status. Clothing can clearly be very effective at inhibiting vitamin D synthesis. Sunscreens are effective in theory and some limited human studies support this. However, most studies show little or no effect and the most likely reason for this is that sunscreens have not been applied in the manner that was used to determine their labelled index of protection against sunburn. This could change in the future if public health campaigns and the sunscreen industry are successful in encouraging the public to apply sunscreens more liberally and/or use much higher levels of labelled protection. The role of melanin on vitamin D status is not clear and requires further investigation.
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    • "Although complete records of participants' skin cancers were available from 1992, we purposely began observation for this incidence study in 1997 to avoid the unusually close dermatological surveillance participants received during the prevention trial (Valery et al., 2004). Since the completion of the trial, we have investigated the long-term protective effect of sunscreen use against BCC and found no significant change in BCC incidence (Van der Pols et al., 2006b). We furthermore showed that there was no impact of the sunscreen intervention on BCC tumor incidence measures in this follow-up study. "
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    ABSTRACT: A proportion of individuals are affected multiple times by basal cell carcinoma (BCC), but the rate and extent to which this occurs is unknown. We therefore prospectively estimated BCC incidence in a subtropical Australian population, focusing on the rate at which persons develop multiple primary BCCs and the precise anatomic sites of BCC occurrence. Between 1997 and 2006, 663 BCCs were confirmed in 301 of 1,337 participants in the population-based Nambour Skin Cancer Study. The incidence of persons affected multiple times by primary BCC was 705 per 100,000 person years compared to an incidence rate of people singly affected of 935 per 100,000 person years. Among the multiply and singly affected alike, site-specific BCC incidence rates were far highest on facial subsites, followed by upper limbs, trunk, and then lower limbs. We conclude that actual BCC tumor burden is much greater in the population than is apparent from normal incidence rates. Anatomic distribution of BCC is consistent with general levels of sun exposure across body sites.
    Journal of Investigative Dermatology 08/2008; 129(2):323-8. DOI:10.1038/jid.2008.234 · 6.37 Impact Factor
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    ABSTRACT: Despite the billions of health care dollars spent each year on treating skin cancer, there is a dearth of randomized controlled trials (RCTs) that have evaluated skin cancer prevention. RCTs published in the last 3 years that have directly assessed skin cancer prevention as their primary aim suggest that regular use of sunscreen is cost effective, but prolonged use of topical therapies such as tretinoin and 5-fluorouracil may not be. Sirolimus-based immunosuppression for secondary skin cancer prevention in long-term renal transplant recipients appears effective, but benefits may be offset by the adverse effects. Many RCTs using pre-invasive actinic keratoses (AKs) as endpoints are too small and/or too short to provide evidence on skin cancer prevention. Another stumbling block is the difficulty in reproducibly diagnosing and counting AKs in response to preventive agents. Longer term and better surveillance methods are urgently required to improve the quality of evidence from future RCTs.
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