Risk Factors | Cancer Prevention Institute of Canada

The most significant preventable risk factor for developing skin cancer is exposure to the sun’s UV radiation. Most significantly, about 90% of malignant melanomas can be attributed to UV exposure.[1] UV radiation has been called

the most prominent and ubiquitous physical carcinogen in the natural environment.[2] This creates an obvious target for preventive healthcare, namely, reduced UV exposure.

Both Canada and the US have review processes and guidelines institutionalized in public bodies whose mandate included clinical and public health responses to UV exposure reduction. In Canada, there is the Canadian Task Force on Preventive Health Care (formerly the Canadian Task Force on the Periodic Health Examination) which disseminates a guide focusing mainly on clinical preventive health care; the counterpart in the US is the Preventive Services Task Force, on which the Canadian work is highly dependent. In terms of population health, the US also has the parallel Task Force on Community Preventive Services (TFCPS). This Task Force has conducted major reviews of smoking prevention and physical activity intervention which figured prominently in earlier sections of this report. Skin cancer prevention is another area which has been recently completed by the group.[3]

The TFCPS organized the topic of skin cancer prevention into three groups, all of which focused on the major risk factor of UV exposure: setting-specific, target-population-specific, and community-wide interventions. As most of the target groups get well handled under the settings (e.g., school-aged children under schools), only one required special treatment, i.e., the parents or other caregivers of children.[4] The organization categories used by other researchers will be adapted and standardized to follow the pattern of preceding sections of this report.

From the point of view of the TFCPS, there appears to be much more research needed.[5] The Task Force only identified two intervention categories with sufficient evidence to warrant a positive recommendation: education and policy approaches in primary schools and recreation / tourism settings. The effects in these two cases were small-to-moderate, but as they occurred in populations rather than individuals, the public health benefit could still be substantial. Summaries of the Task Force results[6] and those of Canadian and other systematic reviews follow. The relevant Cochrane review is still at the protocol stage.[7]

Community-based Interventions

Community programs involve combinations of individual-directed strategies in multiple settings, media campaigns, and sometimes environmental and policy changes. The campaign is usually conducted in a circumscribed geographical area and lasts, by definition, for at least a year.[8] The TFCPS assessed the 8 qualifying studies as having overall limitations in design and execution, and therefore could not draw a positive conclusion for this type of intervention. One randomized study that did show a positive effect involved 10 towns in New Hampshire; the proportion of children using some sun-protection increased significantly in the intervention towns (from 78 to 87%), compared with a decline in the control towns.[9] Office-based counselling by physicians was one of the components in this campaign, and parents reported that they received more information about sun protection from such professionals in the intervention towns (though the focus was again more on sunscreen use rather than other strategies).[10] An earlier US review was more positive about overall community-wide results, though, as with any large-scale intervention, it could not rule out “the possibility that improvements in sun protection reflect secular society-wide trends or response bias prompted by exposure to the program.”[11] Another challenge is identifying the precise strategies in a multi-component intervention that most contributed to any positive results.

Mass Media Campaigns

Mass media campaigns typically have used public service announcements and multimedia information kiosks, sometimes supported by “small media” such as brochures, newsletters and video. A unique public intervention regarding sun protection is the UV index (UVI) reported or broadcast in the media; the UVI presents a warning about the strength of the sun’s rays on a particular day, along with advice on “taking cover.”

Only 3 studies qualified in the TFCPS review of mass media interventions, too few to establish a pattern of effectiveness.[12] The one assessment of the UVI demonstrated a high level of awareness of the index in the population of 58 towns where such information was broadcast; among the aware group, 38% said they had changed their sun protection practices.[13] A Swedish trial offered more equivocal evidence for interventions involving UV information from the UVI or a personal radiation indicator device; though some sun-related beliefs and behaviours changed, sunbathing and sunburn did not decrease more than in a group offered general written information.[14]

A brief review identified 2 additional UK studies, but derived the same conclusion, namely, that response to mass media campaigns alone is at best mixed.[15]

Recreation / Tourism Settings

Beaches and other outdoor recreation sites offer important platforms for sun protection initiatives.[16]

Interventions, which are aimed at adults and children, have included educational brochures; sun-safety training of lifeguards, aquatic instructors and outdoor recreation staff; lessons and interactive activities; increasing shaded areas; provision of sunscreen; and / or point-of-purchase prompts. The outcome examined by the TFCPS was improvement in sun-protective “covering up”; the 11 studies (only 5 were high quality) did point to a modest 11.2% median relative increase in such behaviour by adults (but only provided equivocal evidence for children).[17]

One of the best results was obtained with a multi-component intervention involving education and tailored assessment reports; sun protection behaviours among people recruited at beaches occurred at double the rate of the control group at 24 month follow-up.[18] One reason for the general success of these programs is the fact that they tended to be more rigorously planned and intensive interventions when compared with those in other settings.[19] The potential impact of expanding such efforts in many outdoor settings (e.g., zoos, sporting events) is large.

Workplace-based Interventions

Single and multi-component interventions have been used with workers to increase sun protective intentions or behaviours among workers. As with the school settings, the multiple component approach makes it difficult to isolate the effects attributable to a specific approach. Typical interventions have included some combination of:

The TFCPS reviewed 8 studies which again were not considered to provide sufficient evidence to draw a conclusion about effectiveness. The main recommendation was to pursue more research, and especially to look for interventions with strong results that could be incorporated into the workplace with minimal disruption to its main functions.[20]

School-based Interventions

Child Care Centres

Educational and policy approaches in child care centres are designed to decrease sunburns or increase sun-protective knowledge, attitudes, intentions and behaviours. Intervention components have included curriculum for classroom and take-home activities, brochures for parents, staff education, and a working session to develop plans and policies. The latter included some combination of increasing sunscreen use, promoting sun-protective clothing, avoidance of peak sun hours, and increasing provision of shade and / or encouraging playing in shade. Only two studies qualified in the TFCPS review, which did not provide sufficient data for the Task Force to make a recommendation.[21]

Primary Schools

The intervention aims with younger grade-school children are similar to those described for child care centres. The components include some combination of:

The TFCPS identified 20 studies, but only found 6 of them to be of the highest quality. The median relative increase in sun-protective behaviour was 25%. Only one study looked at decreasing sunburns as a proxy for decreased sun exposure. There was inconsistent evidence about the impact of interventions aimed at avoiding peak sunlight times.[22] An earlier US review of skin cancer prevention for children was positive about the impact of school curricula to change sun-safety behaviours, though a multi-unit approach was required. Changes as a result of short presentations were highly variable, very small or nonexistent.[23] A study published in 2004 further reinforces the value of curricular interventions, e.g., three times more children in the intervention group used long-sleeve shirts and hats.[24]

Secondary School / College

Educational policy and approaches have been aimed at decreasing sunburns and increasing sun-protective knowledge, attitudes and behaviours among adolescents and young adults. Interventions include classroom teaching, home activities, internet-based material, small media (e.g., brochures, fact sheets, sunscreen samples, class credit and / or cash incentives). Although the TFCPS found 13 studies, they were not considered substantial enough or of sufficient quality to warrant a conclusion on effectiveness.[25] A modest review of UK interventions included one study which did not contradict this conclusion.[26]

Home-based Interventions

Interventions oriented to parents or other caregivers are aimed at changing their behaviour, though the ultimate goal is to change the level of protection enjoyed by the children under their care. Single or multi-component approaches have included one or more of the following:

The TFCPS did not find sufficient evidence among 9 qualifying studies to recommend this intervention category as effective in improving sun-protective attitudes or behaviours. A recent result of interest is the positive correlation between a parent’s sun-safe practices and those of their adolescent children.[27],[28] Efforts to improve parental modeling, as occurred in one UK study,[29] might produce downstream effects with children. Apart from their example and persuasion, parents also “often control the environment and organizational policies that promote or hinder protection for children.”[30]

Clinical Interventions and Management

There are two categories of interventions relevant to healthcare settings, namely, the counselling and other services provided to patients and the attempts to improve the effectiveness of providers such as physicians and pharmacists.

The TFCPS looked at the education of healthcare providers through teaching sessions, internet, video and role-modeling. Although 11 studies were identified, they were lacking in one significant regard, i.e., in not measuring the improvements in knowledge and sun-protective behaviour among clients rather than providers.[31] Continued attention to improving clinical effectiveness is advisable as physicians are reported to be the top desired source for sun protection information.[32] An important result from a Canadian study noted a high correlation between sun protective behaviours and having received physician advice.[33]

Counselling

As for the interventions actually used by healthcare providers, the most notable one is counselling. According to a somewhat outdated report by the Canadian Task Force on Preventive Health Care, there are few data on the effectiveness of counselling patients to protect themselves from sunlight. [34] Most studies of counselling have examined intermediate outcomes such as knowledge and attitudes rather than changes in sun-protective behaviour. An exception is a before/after study which evaluated counselling at the time of skin cancer removal; increased use of protective measures and reduced deliberate tanning were observed on 2-6 year follow-up, but it is not clear how much the effect could be attributed to the surgery itself.[35]

The conclusion of the Canadian Task Force was that there was insufficient evidence to recommend for or against counselling, but that it was still prudent to counsel, especially those patients with established risk factors for skin cancer (e.g., light-coloured skin). This recommendation, consistent with the advice of major healthcare organizations, was based on the low risk and cost of such counselling and the potentially large health benefits. The counselling should focus on sun avoidance and protective clothing. [36] The parallel US work in this area includes newer studies, but with substantially the same conclusions.[37] The latter report does offer additional data on two important and controversial topics, namely, sunscreens and tanning salons. Although it also fits under other categories, it is convenient to cover sunscreens at this point, whereas tanning devices will be briefly outlined in the section below which deals with regulations.

Sunscreens

The evidence only supports the modest effectiveness of sunscreen for preventing squamous cell carcinoma and its precursor, solar keratoses.[38],[39],[40] There is insufficient evidence for a positive effect on basal cell carcinoma or melanoma, and even some evidence that relying on sunscreen could increase the risk of contracting these conditions.[41],[42],[43] Recently, the International Agency for Research on Cancer of the World Health Organization concurred with these cautions concerning dependence on sunscreen.[44] These results have not fully penetrated into clinical practice; one survey of paediatricians showed that 60% usually or always counsel about skin protection, but that their advice normally focuses on using sunscreen.[45] Likewise, the general public is still confident in sunscreens; a recent study showed that parents typically used sunscreen to protect their children at the beach rather than sun avoidance or protective clothing.[46]

There has been research on other topical and systemic agents to protect against solar damage. The most promising to date has been a polyphenolic extract from green tea.[47] Retinoids, synthetic derivatives of Vitamin A taken orally by prescription, have been found to be chemoprotective against skin cancer,[48] as have lipid-lowering agents for heart disease.[49]

Regulatory and Economic Interventions

Artificial Tanning Devices / Beds

About a third of 19 case-control studies[50] reviewed found a positive association between the use of artificial tanning devices and melanoma risk, but most did not adjust for confounders such as recreational sun exposure. Of the 9 studies which examined duration, frequency or timing of tanning device exposure, 4 found a positive association with melanoma risk. The strongest link was with a high lamp exposure and / or an experience of burning.

The evidence for precisely how to regulate warnings (or counsel) in reference to artificial tanning devices remains somewhat equivocal. There is new data suggesting that the supposedly safer long-wavelength UV-A rays that are the staple of tanning devices can also damage the skin, and especially increase the risk of non-melanoma skin cancers.[51] This only increases the need to confirm the science and clarify the policy as soon as possible.

Potential Harms of Skin Protection

There are limited data about the potential harms of counselling or of specific sun-safety behaviours. Sunscreen use can lead to a “false sense of security.”[52] One RCT with young adults found that those using a sunscreen with a high sun protection factor (SPF) stayed longer in the sun than those using sunscreen with a lower SPF.[53] A similar issue exists around “fake tan” products which some people mistakenly believe are protective against sunburns. Recent studies of this phenomenon have been conducted in Australia, the country with the highest skin cancer rates in the world.[54],[55]

Other unproven concerns of sun-safety measures focus on reduced vitamin D with sunscreen use and lower levels of physical activity and mental health with sun avoidance strategies.[56]

These cautions necessitate the careful development of any policy related to sunscreens or other sun-protective strategies.

Social Normalization

Since so many public prevention strategies to reduce solar UV exposure have been ineffective, there has been a suggestion that the best way forward is to influence social norms. The parallel is with the public stigma that is now firmly attached to smoking in more and more populations and settings. The proposal in the case of UV exposure is to decrease “the present utility of a suntan.”[57] Society needs to counteract the immediate benefits associated with a tan, especially in light of how distant in the future the health costs of UV radiation will normally be felt. For children and teens, the social norm needs to become fair skin and protective clothing.

The ever-influential arena of popular movies may become the best influencer at this point; the image of pale-skinned film stars may be more effective than sunscreen in reducing harmful UV exposure

. Public policies need to reinforce any momentum towards a normative shift in society, e.g., planting shade trees, planning events at times when sunlight is at low intensity, and requiring better design and ultraviolet protection factor labelling in summer clothing.[58] One of the most significant impacts could be made in school settings were the norm to become the use of sun-protective clothing and /or sunscreen at all outdoor play times.[59],[60] So far, studies of such policy and environmental changes have been limited.[61]

[1] BC Ministry of Health Services, Preventive Health Programs. Available at

http://www.healthservices.gov.bc.ca/prevent/sunsmart.html (accessed November 2004).

[2] de Gruijl FR. Skin cancer and solar UV radiation European Journal of Cancer 1999; 35(14): 2003-9.

[3] Saraiya M, Glanz K, Briss P et al. On reducing exposure to ultraviolet light. Preventing skin cancer: findings of the Task Force on Community Preventive Services Morbidity & Mortality Weekly Report. Recommendations & Reports 2003; 52(RR-15): 1-12.

[4] Saraiya M, Glanz K, Briss P et al. On reducing exposure to ultraviolet light. Preventing skin cancer: findings of the Task Force on Community Preventive Services Morbidity & Mortality Weekly Report. Recommendations & Reports 2003; 52(RR-15): 1-12.

[5] More Research is Needed to Determine Effectiveness of Many Program Approaches to Improve Sun-Protective Behaviors. The Community Guide. Available at http://www.thecommunityguide.org /cancer/skin/default.htm (accessed November 2004).

[6] This report will be dependent on the results from the TFCPS provided on The Community Guide website as the full published paper was yet not available. The citation for the peer-reviewed version is Saraiya M, Glanz K, Briss PA et al. Interventions to prevent skin cancer by reducing ultraviolet radiation: a systematic review American Journal of Preventive Medicine 2004; 27(5): 422-66.

[7] Naldi L, Buzzetti R, Cecchi C et al. Educational programmes for skin cancer prevention Cochrane Skin Group Cochrane Database of Systematic Reviews, 2003.

[8] The Community Guide. Available at http://www.thecommunityguide.org/cancer/skin/default.htm (accessed November 2004).

[9] Dietrich AJ, Olson AL, Sox CH et al. Persistent increase in children's sun protection in a randomized controlled community trial Preventive Medicine 2000; 31(5): 569-74.

[10] Dietrich AJ, Olson AL, Sox CH et al. Persistent increase in children's sun protection in a randomized controlled community trial Preventive Medicine 2000; 31: 569-74.

[11] Buller DB, Borland R. Skin cancer prevention for children: a critical review Health Education & Behavior 1999; 26(3): 317-43.

[12] The Community Guide. Available at http://www.thecommunityguide.org/cancer/skin/default.htm (accessed November 2004).

[13] Geller AC, Hufford D, Miller DR et al. Evaluation of the Ultraviolet Index: media reactions and public response Journal of the American Academy of Dermatology 1997; 37(6): 935-41.

[14] . Branstrom R, Ullen H, Brandberg Y. A randomised population-based intervention to examine the effects of the ultraviolet index on tanning behaviour European Journal of Cancer 2003; 39(7): 968-74.

[15] Melia J, Pendry L, Eiser JR et al. Evaluation of primary prevention initiatives for skin cancer: a review from a UK perspective British Journal of Dermatology 2000; 143(4): 701-8.

[16] Weinstock MA, Rossi JS, Redding CA et al. Sun protection behaviors and stages of change for the primary prevention of skin cancers among beachgoers in southeastern New England Annals of Behavioral Medicine 2000; 22(4): 286-93.

[17] Saraiya M, Glanz K, Briss P et al. On reducing exposure to ultraviolet light. Preventing skin cancer: findings of the Task Force on Community Preventive Services Morbidity & Mortality Weekly Report. Recommendations & Reports 2003; 52(RR-15): 1-12.

[18] Weinstock MA, Rossi JS, Redding CA et al. Randomized controlled community trial of the efficacy of a multicomponent stage-matched intervention to increase sun protection among beachgoers Preventive Medicine 2002; 35(6): 584-92.

[19] By comparison, low intensity interventions are not recommended; e.g., merely offering leaflets on sun protection through travel agents and tour operators has had no effect. Dey P, Collins S, Will S et al. Randomised controlled trial assessing effectiveness of health education leaflets in reducing incidence of sunburn British Medical Journal 1995; 311: 1062-3.

[20] The Community Guide. Available at http://www.thecommunityguide.org/cancer/skin/default.htm (accessed November 2004).

[21] The Community Guide. Available at http://www.thecommunityguide.org/cancer/skin/default.htm (accessed November 2004).

[22] Saraiya M, Glanz K, Briss P et al. On reducing exposure to ultraviolet light. Preventing skin cancer: findings of the Task Force on Community Preventive Services Morbidity & Mortality Weekly Report. Recommendations & Reports 2003; 52(RR-15): 1-12.

[23] Buller DB, Borland R. Skin cancer prevention for children: a critical review Health Education & Behavior 1999; 26(3): 317-43.

[24] Stankeviciute V, Zaborskis A, Petrauskiene A et al. Skin cancer prevention: children's health education on protection from sun exposure and assessment of its efficiency Medicina 2004; 40(4): 386-93.

[25] The Community Guide. Available at http://www.thecommunityguide.org/cancer/skin/default.htm (accessed November 2004).

[26] Melia J, Pendry L, Eiser JR et al. Evaluation of primary prevention initiatives for skin cancer: a review from a UK perspective British Journal of Dermatology 2000; 143(4): 701-8.

[27] Cokkinides VE, Weinstock MA, Cardinez CJ et al. Sun-safe practices in U.S. youth and their parents: role of caregiver on youth sunscreen use American Journal of Preventive Medicine 2004; 26(2): 147-51.

[28] O'Riordan DL, Geller AC, Brooks DR et al. Sunburn reduction through parental role modeling and sunscreen vigilance Journal of Pediatrics 2003; 142(1): 67-72.

[29] Fleming C, Newell J, Turner S et al. A study of the impact of Sun Awareness Week 1995 British Journal of Dermatology 1997; 136: 719-24.

[30] Buller DB, Borland R. Skin cancer prevention for children: a critical review Health Education & Behavior 1999; 26(3): 317-43.

[31] The Community Guide. Available at http://www.thecommunityguide.org/cancer/skin/default.htm (accessed November 2004).

[32] Weinstein JM, Yarnold PR, Hornung RL. Parental knowledge and practice of primary skin cancer prevention: gaps and solutions Pediatric Dermatology 2001; 18(6): 473-7.

[33] Boggild AK, From L. Barriers to sun safety in a Canadian outpatient population Journal of Cutaneous Medicine & Surgery 2003; 7(4): 292-9.

[34] Feightner JW. Prevention of Skin Cancer. 1994. Available at http://www.hc-sc.gc.ca/hppb/healthcare/pdf/clinical_preventive/s10c70e.pdf (accessed November 2004).

[35] Robinson JK. Compensation strategies in sun protection behaviors by a population with nonmelanoma skin cancer Preventive Medicine 1992; 21: 754-65.

[36] Feightner JW. Prevention of Skin Cancer. 1994. Available at http://www.hc-sc.gc.ca/hppb/healthcare/pdf/clinical_preventive/s10c70e.pdf (accessed November 2004).

[37] US Preventive Services Task Force. Counseling to Prevent Skin Cancer, 2003. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5215a2.htm (accessed November 2004).

[38] A small lump on the skin which is caused by a lot of exposure to sun over the years.

[39] Green A, Williams G, Neale R et al. Daily sunscreen application and beta-carotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial The Lancet 1999; 354: 723-9.

[40] Thompson SC, Jolley D, Marks R. Reduction of solar keratoses by regular sunscreen use New England Journal of Medicine 1993; 329: 1147-51. Note: a keratosis is a skin condition marked by an overgrowth of layers of horny skin which can manifest as pink/reddish scaly lesions; can be a pre-cancerous marker.

[41] Westerdahl J, Olsson H, Masback A et al. Is the use of sunscreens a risk factor for malignant melanoma? Melanoma Research 1995; 5: 59-65.

[42] Huncharek M, Kupelnick B. Use of topical sunscreens and the risk of malignant melanoma: a meta-analysis of 9067 patients from 11 case-control studies American Journal of Public Health 2002; 92: 1173-7.

[43] Autier P, Dore JF, Luther H. The case of sunscreens revisited Archives of Dermatology 1998; 134: 509-10.

[44] International Agency for Research on Cancer (IARC). Handbooks of Cancer Prevention: Sunscreens. Vol. 5. Lyon, France: IARC Press, 2001.

[45] Easton A, Price J, Boehm K et al. Sun protection counseling by pediatricians Archives of Pediatrics & Adolescent Medicine 1997; 151: 1133-8.

[46] Boyett T, Davy L, Weathers L et al. Sun protection of children at the beach Journal of the American Board of Family Practice 2002; 15(2): 112-7.

[47] Scarlett WL. Ultraviolet radiation: sun exposure, tanning beds, and vitamin D levels. what you need to know and how to decrease the risk of skin cancer Journal of the American Osteopathic Association. 2003; 103(8): 371-5.

[48] Reilly P, DiGiovanna JJ. Retinoid chemoprevention in high-risk skin cancer patients Dermatology Nursing 2004; 16(2): 117-20, 123-6.

[49] Dellavalle R, McNealy K, Graber M et al. Lipid-lowering agents for preventing melanoma. Cochrane Skin Group Cochrane Database of Systematic Reviews, 2003.

[50] Swerdlow AJ, Weinstock MA. Do tanning lamps cause melanoma? An epidemiologic assessment Journal of the American Academy of Dermatology 1998; 38: 89-98.

[51] Autier P, Dore JF. Influence of sun exposures during childhood and during adulthood on melanoma risk. EPIMEL and EORTC Melanoma Cooperative Group. European Organisation for Research and Treatment of Cancer International Journal of Cancer 1998; 77(4): 533-7.

[52] US Preventive Services Task Force. Counseling to Prevent Skin Cancer. 2003. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5215a2.htm (accessed November 2004).

[53] Autier P, Dore JF, Negrier S et al. Sunscreen use and duration of sun exposure: a double-blind, randomized trial Journal of the National Cancer Institute 1999; 91: 1304-9.

[54] Girgis A, Tzelepis F, Paul CL et al. Australians' use of fake tanning lotions: another piece of the puzzle Australian & New Zealand Journal of Public Health 2003; 27(5): 529-32.

[55] Beckmann KR, Kirke BA, McCaul KA et al. Use of fake tanning lotions in the South Australia population Medical Journal of Australia 2001; 174: 75-8.

[56] US Preventive Services Task Force. Counseling to Prevent Skin Cancer 2003. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5215a2.htm (accessed November 2004).

[57] Feldman SR, Dempsey JR, Grummer S et al. Implications of a utility model for ultraviolet exposure behavior Journal of the American Academy of Dermatology 2001; 45(5): 718-22.

[58] Gambichler T, Rotterdam S, Altmeyer P et al. Protection against ultraviolet radiation by commercial summer clothing: need for standardised testing and labelling BMC Dermatology 2001; 1(1): 6.

[59] Feldman SR, Dempsey JR, Grummer S et al. Implications of a utility model for ultraviolet exposure behavior Journal of the American Academy of Dermatology 2001; 45(5): 718-22.

[60] Guidelines for School Programs to Prevent Skin Cancer Morbidity & Mortality Weekly Report 2002; 51(RR-4): 1-18.

[61] Buller DB, Borland R. Skin cancer prevention for children: a critical review Health Education & Behavior 1999; 26(3): 317-43.

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