Evidence based Dermatology - part 5 pot

and type, and patient sex, age and site with survival. Cancer 1983; 52 :1330–41. 34. Friedman RJ, Rigel DS, Kopf AW. Early detection of malignant melanoma: the role of the physician examination and self examination of the skin. CA Cancer J Clin 1993; 35 :130–51. 35. MacKie RM, Hole D. Audit of public education campaign to encourage earlier detection of malignant melanoma. BMJ 1992; 304 :1012–15. 36. Melia J, Moss S, Graham-Brown R. et al. The relation between mortality from maliganant melanoma and early detection in the Cancer research Campaign Mole Watcher Study. Br J Cancer 2001; 85 :803–7. 37. Farmer ER, Gonin R, Hanna MP. Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists. Hum Pathol 1996; 27 :528–31. 38. Berwick M, Begg CB, Fine JA. Screening for cutaneous melanoma by skin self-examination. J Natl Cancer Inst 1996; 88 :17–23. 39. Ferrini RL, Perlman M, Hill L. Screening for Skin Cancer. American College of Preventive Medicine: Practice Policy Statement, 1998. Am J Prev Med 1998; 14 :80–2. 40. Asri GD, Clarke WH Jr, Guerry DV et al. (1990) Screening and surveillance of patients at high risk for malignant melanoma result in the detection of earlier disease. J Am Acad Dermatol 1990; 22 :1042–8. 41. Melia J, Harland C, Moss S, Eiser JS, Pendry L. Feasibility of targeted early detection for melanoma: a population-based screening study. Br J Cancer 2000; 82 : 1605–9. 42. Altman JF, Oliveria SA, Christos PJ, Halpern AC. A survey of skin cancer screening in the primary care setting: a comparison with other cancer screenings. Arch Fam Med 2000; 10 :1022–7. 43. Lorentzen HF, Weismann K. Dermatoscopic diagnosis of cutaneous melanoma. Secondary prophylaxis. Ugeskr Laeger 1993; 162 :3312–16. 44. Bafounta ML, Beauchet A, Aegerter P, Saiag P. Is dermoscopy useful for the diagnosis of melanoma? Results of a meta-analysis using techniques adapted to the evaluation of diagnostic tests. Arch Dermatol 2001; 137 :1343–50. 45. MacKie RM, Fleming C, McMahon AD, Jarrett P. The use of dermatoscope to identify early melanoma using the three colour test. Br J Dermatol 2002; 146 :481–4. 46. Girgis A, Sanson-Fisher RW. Skin cancer prevention, early detection, and management: current beliefs and practices of Australian family physicians. Cancer Detect Prev 1996; 20 :16–24. 284 Evidence-based Dermatology Background Historical development and SPF Sunscreens were first used in1928 and became popular with those intentionally trying to gain a suntan. They mainly filter out the wavelengths responsible for sunburn (UVB, 280–315 nm). Following evidence that longer wavelengths of sunlight (UVA, 315–400 nm) are involved in the sunburn reaction and photocarcinogenesis, UVA absorbers have been added to most sunscreens to widen their absorption spectra. There is concordant evidence that sunscreens undoubtedly protect against sunburn, but evidence for a role in the prevention of skin cancers is still somewhat equivocal. 1,2 The concept of a sunscreen effectiveness index (ratio) is attributed to Schulze and Greiter, who proposed the specific term “sun protection factor” (SPF), and the associated method for assessing SPF. 3 SPF activity is the ratio of the least amount of UV energy required to produce erythema (reddening of the skin) on sunscreen- protected skin to the amount of energy to produce the same effect on unprotected skin. Testing and regulation of sunscreens Topical sunscreens applied to the skin act by absorbing and/or scattering incident UV radiation (UVR). The shape of the absorption spectrum is the fundamental attribute of a topical sunscreen. It is expressed as the extinction coefficient: the measure of the degree to which the sunscreen absorbs individual wavelengths across the terrestrial UVR spectrum (290–400 nm). Absorption is the product of the extinction coefficient, the concentration of the active ingredient, and the effective thickness of application on exposed parts of the body. Sunscreens are regulated for specific formulations in most countries. In the EU, Japan, and South Africa they are regulated as 23 Do sunscreens reduce the incidence of skin cancers? Ros Weston 285 Figure 23.1 Patient with sunburn and dysplastic naevus syndrome cosmetics and in other countries (Australia, Canada and New Zealand) as drugs. Testing for toxic effects is mandatory in each country. Control in Europe is by a directive of the European Commission (2000). This mandates that labelling should include a full list of ingredients in decreasing order of concentration, and that this should be displayed on the containers of all cosmetics that include sunscreen formulations. 4–7 Sunscreens are now readily available in most countries during all seasons. In Australia the availability of sunscreens has been maximised through sales tax exemptions and they are now available in workplaces, schools; their use by children is actively promoted. 8–10 Paradoxical findings: problems with use of sunscreen as a primary prevention aim Protecting against sun damage and reducing the risk of sunburn and skin cancers involves behavioural choices. Studies demonstrate that increased use of sunscreens often means a reduction in other photo-protective methods: wearing of hats and protective clothing and the use of shade (see Figure 22.1), thus increasing net sun exposure. Most sunscreens are made to prevent against sunburn and most sunburn, in both children and adults, occurs during intentional exposure to the sun. 11–14 The use of sunscreens, including those with high SPFs, during intentional exposure has been found to have little effect on the occurrence of sunburn. 15–17 This is concordant with the results from surveys of beachgoers which suggest that increased overreliance on sunscreens reduces the use of other protective measures. Individuals seem to balance protective behaviours according to personal motivation and characteristics and the desire for a suntan. 18–24 Intended and actual sun protection from sunscreens There is some evidence that the numerical measure of protection indicated on the product pack is generally higher than that achieved in practice. The photoprotection of sunscreens (the SPF) is measured by photo-testing in vivo at internationally agreed levels of thickness of application 2 mg/cm 2 . To receive the SPF quoted on sunscreen packaging, an individual would need to use 35 ml of sunscreen for total body surface protection. Studies have demonstrated that individuals are more likely to use 0·5–1·5 mg/cm 2 and that most users get, in protective terms, the benefit of between one- quarter and one-half of the product. 25 Individuals get sunburnt because they use too little sunscreen, spread it unevenly, miss parts of the body surface exposed to the sun and because sunscreen is rubbed or washed off. Thus, individuals’ use of a sunscreen makes a difference in how effective sunscreens are in the prevention of sunburn and explains why sunburn still occurs even with higher SPF sunscreens. If individuals want to be supine in the sun for long periods of time (hours) then it is recommended that SPFs of 20–30 or higher are necessary. Sunscreens need to be applied evenly 30 minutes before going out in the sun. They need to be reapplied at regular intervals as much is washed off by swimming and other water sports and by any abrasive action particularly from sand on the beach. 25 Possible drawbacks of sunscreens No published studies have demonstrated toxic effects of sunscreens in humans. Case reports suggest there is an increase in the frequency of photocontact dermatitis among patients who are frequent sunscreen users and who have photodermatoses such as polymorphic light eruption. There is no evidence that sunscreen use affects vitamin D levels. 25 Using sunscreen does not cause adverse effects on reproduction 286 Evidence-based Dermatology or fetal development, although some effects have been seen with high oral doses of sunscreen ingredients in animal models. In some experimental conditions topically applied sunscreen (in the absence of UVR) affects the immune system but most toxicity studies have shown that the active ingredients in sunscreens are safe when applied topically at recommended concentrations. DNA damage has been reported in one study. 25 Search strategies Searches of Medline, PubMed and the Cochrane Library was carried out using “sunscreen” as a key word and searching for appropriate meta- analyses and randomised controlled trials (RCTs). Health education and promotion journals were also searched. This search located the International Agency for Research on Cancer (IARC) meta-analysis of sunscreen use. 25 Outcome measures Ideally, the main outcome measure of studies addressing sunscreen use and cancer risk would be numbers of incident cancers in those using sunscreens compared with those not using sunscreens. However, this is unrealistic because of the long latency period for a skin cancer to develop and the relative rarity of such events. Surrogate outcome measures such as reported protective behaviour are therefore often used in studies. Intermediate outcomes such as incidence of actinic keratoses or reduction in naevi are also used as short-term surrogates for longer term skin cancer risk. All of these surrogate measures have their problems. There are many confounding factors when assessing sunscreen use. Many studies use behaviour (for example, reported use of suncreen or sun avoidance) as the outcome measure. The data may still be unreliable as recall of use is not necessarily accurate and other protective measures are confounding factors. Lack of specificity of outcome measures remains problematic. QUESTIONS Can the use of sunscreen prevent cutaneous melanoma? Efficacy There are no reported RCTs or cohort studies on the use of sunscreens and the risk for cutaneous melanoma. There are a total of 15 case-control studies 26–40 (see Table 23.1). In attempting to assess the evidence from these it is important to note that these studies use very different populations and different cultural groups. This analysis does not compare like with like: each uses a different study design, has different terms of reference and uses different methods for data collection. The term sunscreen is variously described and does not refer to one category. Sun lotion, sun-tanning oil and sun protection factor are used throughout these studies. This makes it particularly difficult to assess the reported results unless these terms were clearly defined to study participants, or confounding factors accounted for, as part of the data analysis process. Overall, however, these studies showed on overall low prevalence of sunscreen use (see Table 23.1) Klepp and Magnus (1979) 26 , Graham et al. (1985) 27 and Herzfeld et al. (1985) 28 reported an increased risk between sunscreen use and melanoma with Graham et al. reporting an increased risk particularly in males. Beitner et al. (1990) 29 reported increased risk for those who used sunscreens “often” or “very often”. This study controlled for age, sex and hair colouring. Elwood and Gallagher (1999) 30 assessed the relationship between phenotype, history of sun- tanning and sunburn, exposure to sunlight and the risk for melanoma in four western provinces of Canada. Analysis of a subset of cases of 287 Do sunscreens reduce the incidence of skin cancers? 288 Evidence-based Dermatology Table 23.1 Case-control studies of sunscreen use and risk for cutaneous melanoma Population Type of cases/ No. cases/ Exposure RR a (95% CI) Comments Reference place/date controls controls Norway 1974–75 USA 1974–80 USA 1977–79 Sweden 1978–83 Canada 1979–81 Australia 1980–81 USA 1981–86 Denmark 1982–85 Australia 1987–94 78 cases 131 controls 404 cases 521 controls 324 male trunk melan- oma cases 415 controls 523 cases 505 controls 369 trunk and lower limb melanomas 369 controls 507 cases 507 controls 452 cases 930 controls 474 cases 926 controls 50 cases 156 controls Sometimes, often or almost always use sun lotion/oil Used sunscreen Used suntan lotion Always used “suntan lotion” Often used sun protection agents Used sunscreen almost always Used sunscreens ≤ 10 years Always used sunscreens Always used sunscreens Always used sunscreens M 2·8 b (1·2–6·7) F 1·0 b (0·42–2·5) T 2·3 b (1·3–4·1) M 2·2 b (1·2–4·1) M 1·7 (1·1–2·7) F “no added risk” 2·6 b (1·4–4·7) Not significant after control for “tendency to sunburn and water sports” 1·8 b (1·2–2·7) 1·1 (0·75–1·6) 1·1 (0·71–1·6) All cutaneous melanoma 0·62 b (0·49–0·83) Superficial spreading melanoma (SSM) 0·43 (CI not available) 1·1 b (0·8–1·5) 2·2 (0·4–12) on holidays Elevated risks among males only. Sunscreens not differentiated from “sun lotions”. Elevated risks among males only “Suntan lotions” and “sunscreens” not differentiated in questionnaire Highest risk in those using sun- screen “only for first few hours” RR,1·62 (1·04–2·52) Study involved only women aged 25–59 at diagnosis. CI estimated. RR for SSM adjusted for host factors and sun exposure Klepp and Magnus (1979) 26 Graham et al . (1985) 27 Herzfeld et al . 28 (1993) Beitner et al . 29 (1990) Elwood and Gallagher 30 (1999) Holman et al . 31 (1986) Holly et al . 32 (1995) Osterlind et al . (1997) 33 Whiteman et al. (1997) 34 Hospital cases Other cancer controls Hospital cases Other cancer controls Population cases and controls Hospital cases Population controls Population cases and controls Population cases and controls Population cases and controls Population cases and controls Population cases Controls from same (Continued) melanoma on intermittently exposed sites (trunk and lower limbs) and controls provided information about the use of sunscreens on these sites during outdoor activity. Risk for those reporting sunscreen “almost always used” was very similar to that of those using sunscreen “sometimes”. Those using sunscreen only in first few hours had increased risk after adjustment for hair, eye and skin colouring and propensity to burn. Holman et al , (1986) 31 found that those who had used sunscreens for less than 10 years did not have a reduced risk for cutaneous melanoma: risk was not reduced for those who had used sunscreens for 10–15 years. Frequency of use did not appear to be related to risk. This study did find a positive relationship between the use of sunscreen and the risk for cutaneous melanoma but in the absence of control for pigmentary traits and sun sensitivity. Sunscreens 289 Do sunscreens reduce the incidence of skin cancers? Table 23.1 ( Continued ) Population Type of cases/ No. cases/ Exposure RR a (95% CI) Comments Reference place/date controls controls Sweden 1988–90 Spain 1989–93 Spain 1990–94 Europe 1991–92 Austria 1993–94 Sweden 1995–97 All children < 15 400 cases 640 controls 105 cases 138 controls 116 cases 235 controls 418 controls 438 controls 193 cases 319 controls 571 cases 913 controls Almost always used sunscreens Always used sunscreens Used sunscreen Ever use psora- len sunscreens Ever use sunscreen Often used sunscreen Always used sunscreen Used sunscreens to spend more time sunbathing 0·7 (0·1–6·0) at school Trunk 1·4 (0·6–3·2) Other sites 2·0 (1·1–3·7) 0·2 (0·04–0·79) 0·48 (0·34–0·71) 2·3 (1·3–4·0) 1·5 (1·1–2·1) M 1·8 (1·1–2·7) F 1·3 (0·87–2·0) 3·5 (1·8–6·6) 1·8 (1·1–2·9) 8·7 (1·0–76) No information on duration of use Inadequate description of measurement of sunscreen use Highest risk for sun-sensitive subjects using sunscreens to tan: RR, 3·7 (1·0–7·6) Westerdahl et al . (1995) 35 Rodenas et al . (1996) 36 Espinoza- Arranz et al. (1991) 37 Autier et al. (1995, 1997b) 38 Wolf et al . (1998) 39 Westerdahl et al. (2000) 40 school Population cases and controls Hospital cases Hospital visitors Hospital cases and controls Hospital cases Neighbourhood controls Hospital cases and controls Population cases and controls a Relative risk estimates adjusted for phenotype and sun-related factors where possible b Crude relative risk ratio only available were not available in Australia when the subjects in this study were younger and therefore they were unable to use them at a time when they may have given protection. Holly et al. (1995) 32 found that women who reported “almost always” using sunscreens had a lower risk for cutaneous melanoma than those who reported that they “never” used sunscreens. After controlling for superficial spread of melanoma, sun sensitivity and sunburn history before the age of 12 years the risk for women "almost always" using was lower than for those “never" using. The authors concluded that sunscreen use was strongly protective against melanoma. This study showed that the highest level of risk was for women with the least exposure after controlling for sun sensitivity. Osterlind et al. (1988) 33 found that compared to those who "never" used sunscreens, a small non- significant increase in risk was seen for those who had used them for less than 10 years, or for those using for more than 10 years. Frequency of use was not associated with the risk of melanoma among those “always using” against those who "hardly ever used" or “never used". Effective sunscreens were not available to the study group in their youth. Whiteman et al. (1997) 34 found, after controlling for tanning ability, freckling and number of naevi, those who had "always" used sunscreens while on holiday had a non-significant elevated risk for cutaneous melanoma compared to those not using sunscreens. The use of sunscreens at school was associated with a non-significant reduced risk. The RRs have very wide confidence intervals in this study (only 11 "always" used on holiday and only two reported sunscreen use at school). Westerdahl et al. (1995) 35 found, after controlling for history of sunburn; history of sunbathing; number of raised naevi; freckling and hair colour, those "almost always" using sunscreen had similar risk estimates to those "never" using in both men and women. Risk for use before age 15, at age 15–19 and at age 19 years reported elevated odds ratios at each stage similar to those of people "always using" sunscreens. Risk for melanomas of the trunk were similar to that found for melanomas of the extremities, and head and neck, after adjustment for sunburns, frequent sunbathing, freckling and naevi. Rodenas et al. (1996) 36 reported that the use of sunscreen appeared to protect against melanoma and that risk was strongly associated to the sensitivity of the skin to the sun (relative risk of 2·0) for those who always burned. This study failed to give a description of how sunscreen use was measured. Espinoza-Arranz et al . (1999) found similar results. 37 Autier et al. (1995 and 1997) 38 found that those who had "never" used psoralen-containing sunscreens had an increased risk for cutaneous melanoma after controlling for age, sex, hair colouring, and number of weeks spent in sunny climes each year. An elevated risk was found particularly among those who reported no history of sunburn. Use of psoralen-containing sunscreens, however, was not common. Those “ever” using these sunscreens (psoralen) also had increased risk after adjustment for some factors compared to those “never” using. Increased risk was reported for those using sunscreens and those having light or dark hair. Sensitive and sun-insensitive participants showed an increased risk with the use of sunscreens. The authors concluded that use of sunscreen tended to be associated with higher risk for cutaneous melanoma among sunbathers. Highest risk was for those using sunscreen and who had no history of sunburn after age 14 years. The use of clothing, rather than sunscreen, appeared protective. It was the use of sunscreen, particularly in UVA as well as UVB light, that was found to associated with increased risk. 290 Evidence-based Dermatology Wolf et al. (1998) 39 reported "often used" sunscreen had a significant higher risk for melanoma compared to “never used” (study controlled for skin colouring, sunbathing and history of sunburn). The authors concluded that use of sunscreen did not prevent melanoma. Westerdahl et al. (2000) 40 reported a significantly increased risk for melanoma for regular use (always used) of sunscreen after adjustment for hair colour, history of sunburns, frequency and duration of sunbathing. Risk was significantly increased among those using sunscreens with an SPF less than 10 compared with those who did not use sunscreens and for those with no history of sunburn when they used sunscreens. The risk was even higher for those using sunscreen to increase sunbathing time (deliberate exposure). In an analysis of subsites, risk was significantly increased only for melanoma of the trunk. The following studies could be assessed as supporting a positive association between sunscreen use and risk of cutaneous melanoma but this tentative conclusion should be viewed cautiously. 26–29,38–40 Confounding factors such as: sunscreen use, sun exposure, sun sensitivity, a history of sun-related neoplasia and sun-protective behaviour such as the use of protective clothing, staying indoors or seeking shade were problematic in these studies. There was idiosyncratic reporting of these confounding factors casting doubt on the significance of the results. Three studies 30,31,33 reported no increased risk for use of sunscreen and cutaneous melanoma with non-significant increase being reported in one study. 34 Three studies reported sunscreen as protective against cutaneous melanoma. 34,36 Studies that have assessed naevus count as an indicator of melanoma risk One study using naevi count as an intermediate endpoint showed that the median number of new naevi in Caucasian children was reduced in the sunscreen users. Sunscreen was more effective in preventing naevi in children who freckled than in those who did not. 41 Difference in exposure time was not a significant variable. One cohort study 42 showed increasing naevi development with sunscreen use. Further analysis showed that this was because children who used sunscreen had longer cumulative exposure time but no data were available to support this conclusion. The cross-sectional study 43 reported that the use of summer sunscreen reduced the number of sunburns but was not associated with annual sun exposure or with naevi number or density. This study was criticised for not reporting all data. Studies using naevus count as an outcome do not provide any conclusive evidence about the relationship between the use of sunscreen and reduced naevi and thus reduced risk for cutaneous melanoma. In all studies the confounding variables and lack of reported data were problematic. A consistent finding of all these studies was the link between cumulative exposure and risk. Comment on sunscreen use and melanoma risk Some studies demonstrate a positive association between sunscreen use and risk for cutaneous melanoma whereas others do not. Many confounding factors prevented any firm conclusions as to the possible protective or harmful effect on the use of sunscreens. The most likely reason for an apparently increased risk is that individuals who use sunscreen stay in the sun longer because they falsely believe that sunscreen protects them. This needs further research, particularly to clarify knowledge and attitudes to suntanning, sunscreen use and knowledge of skin cancer. It would seem that individuals intent on gaining a suntan use sunscreens to give themselves more time in the 291 Do sunscreens reduce the incidence of skin cancers? sun without sunburn. Reducing their risk of cancer is a secondary motive. Risk is also related to phenotype and history of sun exposure and sunburn. There is equivocal evidence about the use of sunscreen and the use of other photo- protective measures. Further research is needed to assess these factors in long-term randomised studies with specific target groups. Such research needs to include a formative stage that seeks to explore knowledge and attitude to sunscreen use and other photo-protective measures. This information will enable specific outcome objectives to be developed for each aspect of the study, thus reducing confounding factors. There is a need for an agreed definition of “sunscreen use” and specific definition and description of such use: how, when and what SPF is used in specific situations. Can the use of sunscreen reduce the risk of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)? The Nambour Skin Cancer Prevention Trial (a randomised study exploring risk of both SCC and BCC) demonstrated that sunscreen use could be significant in reducing the risk of SCC. 44 This was a complex trial including 1850 residents aged 20–69. They were invited to use a daily application of SPF 16 sunscreen and use 30 mg of beta-carotene supplement in the prevention of skin cancer; 1647 attended baseline assessment that included a cancer risk factor assessment and a full skin examination by a dermatologist. Any detected skin cancers were removed at the start of the study. Out of these 1647 residents, 1621 agreed to take part in the study. They were randomised to one of four study groups, sunscreen and beta-carotene; sunscreen and placebo; no sunscreen and beta-carotene; and no sunscreen and placebo. The participants attended a clinic every 3 months to receive new sunscreen and beta-carotene. The weight of the sunscreen returned to these clinics every three months was recorded. A random subgroup of sunscreen users kept a 7-day diary on three occasions to record their frequency of sunscreen application and sun exposure. Dermatologist examinations were given at these visits and any cancers removed and recorded. No protective effect for prevention of SCC was found in the beta-carotene group. Sunscreen use was analysed for all groups, regardless of beta- carotene use as no interaction was seen between the two interventions (sunscreen and beta- carotene). A total of 28 new SCCs were detected in the group given sunscreen and 46 in those not given sunscreen (RR, 0·61; 95% CI 0·50–1·6) a statistically significant difference. The authors concluded that sunscreen use could be of significant benefit in protecting against SCC. No placebo sunscreen was used and the results need to be interpreted with caution because the comparison group was not ideal, reducing the power of the study to detect an effect of daily sunscreen use. Green et al. (1999) 45 subsequently reported that solar exposure of those given sunscreen did not differ from those not given sunscreen. The prevalence of sunburn was lower for those receiving sunscreen to those not receiving it (tested on a random sample of participants wearing photosensitive badges). The findings suggest that the reduction of incidence of SCC seen in the group using sunscreens was probably due to the attenuation [sic thinning] of the UVR by the sunscreen rather than in behaviour change (reducing time in the sun). Higher factor sunscreen use, especially for older people, may not result in them spending longer time in the sun. A cohort study by Grodestein et al. (1995) 46 reported that sunscreens used over a 2-year period by women who spent 8 or more hours per week in the sun was not protective by comparison with no use of such agents (RR 1·1; 95% CI 0·83–1·7). Timing of exposure to UVR was a significant risk factor for SCC in a case-control study by Pogoda 292 Evidence-based Dermatology and Preston-Martin (1996). 47 There is little evidence that sunscreen use protects against BCC. Some patients may have been advised to use sunscreens following diagnosis, which may have confounded results. Following diagnosis of SCC, use of sunscreen was examined retrospectively in three age groups: 8–14, 15–19 and 20–24 years. Those in the 8–14 group who had used sunscreens seemed to have a slightly reduced risk of SCC (RR 0·61; 95% CI 0·82–4·4) not statistically significant. Those using sunscreen in the 15–19 age group had a relative risk of 1·9 (95% CI 0·82–4·4) and those in the 20–24 group had a risk of 0·99 (95% CI 0·44–2·2). No strong protective effect of sunscreens was found. One cohort, Hunter et al. (1990) 48 and one case- control study by Kricker et al. (1995) 49 reported increased risks for BCC in sunscreen users. No significant association between sunscreen use and cancer risk was observed in one cohort and one case-control study of SCC 50 , one of SCC and BCC of the skin or one case-control study of SCC of the vermilion border of the lip. 47 Confounding of sun sensitivity and exposure were present in these studies, as in previously described studies. Kricker et al. 49 found that subjects who had used sunscreens for at least half the time spent in the sun 1–9 years prior to diagnosis had a higher relative risk for BCC than those who had never used sunscreens or had used them less than half the time (RR 1·8; 95% CI 1·1–2·9). This risk persisted after adjustment for age, sex, ability to tan and site of lesion. No change in RR was found for those who had used sunscreens more than half the time in the 1–9 years, prior to diagnosis (RR 1·1; 95% CI 0·69–1·7) in comparison to those who had not used sunscreens or who had used them for half the time. Few subjects had access to sunscreens 11–30 years before diagnosis. Studies that have used intermediate end points such as incidence of solar keratoses as markers for basal and SCCs risk Actinic (solar) keratoses are a risk factor for BCC and a precursor lesion for SCC. They are related to solar exposure and phenotype. The rate of development for SCC is low and many regress spontaneously, especially when exposure to UVR is reduced. These lesions have therefore been used as an intermediate endpoint in studies on the use of sunscreens in the prevention of SCC. 47,51 The Maryborough Trial in Australia 51 assessed whether the daily use of sunscreen had any effect in reducing the development of actinic keratoses in those already having these. This was a short-term study using a placebo and included body site examination and diaries to record the time of day patients applied sunscreen. Those using placebo had greater mean increase in the number of keratoses during the study (1·0 ± 0·3 SE) than those given sunscreen (0·6 ± 0·3; RR 1·5; 95% CI 0·81–2·2). Fewer new keratoses were found in the sunscreen group (1·6 versus 2·3 lesions per subject; RR 0·62; 95% CI 0·54–0·71). After controlling for sex and sun sensitivity, the likely remission of keratoses (those with keratoses at the start of study) was greater for the sunscreen group (25% versus 18% initial lesions regressing: RR 1·5, 95% CI 1·3–1·8. 51 Comment on sunscreen use and BCC and SCC There is no conclusive evidence that sunscreen protects against either SCC or BCC and there is some limited evidence to suggest that risk may increase with sunscreen use. However, these non-randomised studies had confounding variables that make it difficult to be conclusive about such evidence. Although the Maryborough acitinic keratoses trial 51 was a short-term trial, the confounding 293 Do sunscreens reduce the incidence of skin cancers? [...]... Eleven out of sixteen targeted interventions were successful in increasing knowledge and behaviour52 ,54 ,56 ,59 ,61–64 and six were successful in increasing solar potection, either the use of shade, staying out of the sun or the use of clothing52 59 ,62,64,68,73 and increased sunscreen use .52 ,54 ,56 58 ,62,64, 65, 66–69 The duration and intensity of the intervention affected the success of the intervention Successful... safety in the sun- An information handout Oncol Nursing Forum 1989;16:424–7 299 Evidence- based Dermatology 71 Reding DJ, Fischer V, Gunderson P, Lapper K Skin cancer prevention: A peer education model Wisconsin Med J 19 95; 94:77–81 72 Friedman LC, Webb JA, Bruse S, Weinberg AD, Cooper HP Skin cancer prevention and early detection intentions and behaviour Am J Prev Med 19 95; 11 :59 – 65 73 Grant-Peterson J,... sunscreen 57 Robinson JK, Rademarker AW Sun protection by families at application and beta-carotene supplementation in the beach Arch Pediatr Adolescent Med 19 95; 152 :466–70 prevention of basal cell and squamous cell carcinomas of 58 Robinson JK, Rademaker AW Skin cancer risk and sun Lancet protection learning by helpers of patients with non- 45 Green A, Williams G, Neale R, Battistutta D Beta- 59 Lombard... interventions combined with sunscreen use .52 –79 Sunscreen use is only one of many outcome measures in these multistrategic interventions targeted at specific groups or to communities in general but was reported separately Seven studies54 ,55 ,60,61,68,71,72 were conducted in schools; four at beaches52 ,57 ,63,69; two at pools52, 75 and three in other recreational settings.62, 65, 67; There were two studies in the... This study therefore seems to have confirmed the relapse-free survival and overall survival benefits of high-dose interferon reported earlier.46 307 Evidence- based Dermatology Low-dose interferon To date, two clinical trials have used low-dose subcutaneous interferon (3 MU three times weekly) in patients presenting with lesions greater than 1 5 mm in depth but with negative lymph nodes In the first... mainly used information giving to raise awareness of primary and secondary prevention of skin cancer .56 ,58 ,60 294 More complex community interventions used incentives for beach guards, booklets52 ,56 ,61, primary and secondary prevention information and education,66,73–76,79 and in schools .54 ,55 ,67,71,73 Twenty-two studies, quasirandomised and longitudinal studies reported on at least one outcome measure... Negrier S et al Sunscreen use and correlates with the absorption spectrum of the sunscreen duration of sun exposure: A double blind randomised trial J Invest Dermatol 19 95: 1 05; 3 45 51 J Natl Cancer Inst 1999;91:1304–9 297 Evidence- based Dermatology 17 McCarthy EM, Ethridge KP, Wagner JF Jr Beach holiday 31 Holman CDJ, Armstrong BK, Heenan PJ Relationship of sunburn: The sunscreen paradox and gender differences... epidermis have no metastatic potential Those that are less than 1 mm in depth have a very good prognosis, with 5- year survival rates of approximately 95% Tumours deeper than 4 mm are associated with survival rates of about 50 % The involvement of regional lymph nodes with metastases at presentation further reduces survival rates to 25 50 %.7 Incidence The incidence of cutaneous MM, particularly thin curable... margins are based on three RCTs and have included patients with lesions of Breslow thickness up to 5 mm The World Health Organization Melanoma Group randomised 612 patients with melanomas less than 2 mm in depth to surgical excision with 303 Evidence- based Dermatology either 1 cm or 3 cm margins. 15 The mean follow up period was 90 months and there was no difference in overall or disease-free survival... over 5 years were 79 5% and 83·7%, respectively The Swedish Melanoma Study Group randomised 769 patients with lesions of 0·8–2 mm in depth to either 2 cm or 5 cm margins, and have recently reported their long-term results with a median follow up period of 11 years.17 The estimated relative hazard ratios for overall survival and relapse-free survival were 0·96 ( 95% confidence intervals (CI) 0· 75 1· 25) . melan- oma cases 4 15 controls 52 3 cases 50 5 controls 369 trunk and lower limb melanomas 369 controls 50 7 cases 50 7 controls 452 cases 930 controls 474 cases 926 controls 50 cases 156 controls Sometimes, often. separately. Seven studies 54 ,55 ,60,61,68,71,72 were conducted in schools; four at beaches 52 ,57 ,63,69 ; two at pools 52 , 75 and three in other recreational settings. 62, 65, 67 ; There were two studies. was a significant risk factor for SCC in a case-control study by Pogoda 292 Evidence- based Dermatology and Preston-Martin (1996). 47 There is little evidence that sunscreen use protects against BCC.