Interventions to prevent skin cancer by reducing exposure to ultraviolet radiation: A systematic review
Introduction
Skin cancer is the most common type of cancer in the United States.1 Estimates for 2004 indicate that more than 1 million people will be diagnosed as having the two most common types of skin cancer—basal cell carcinoma and squamous cell carcinoma—and approximately 2300 deaths from both cancers combined are predicted. Both basal cell and squamous cell carcinoma respond well to treatment. However, melanoma, the third most common type of skin cancer, is much more likely to be fatal. Diagnoses of melanoma are anticipated in approximately 55,000 people and will account for 7900 deaths, more than three quarters of all skin cancer fatalities.2
In the United States, although the incidence of most cancers has been declining, melanoma incidence has been on the rise.3 Since 1973, the annual incidence rate for melanoma (new cases diagnosed per 100,000 people) has more than doubled, from 6.8 per 100,000 in that year to 17.4 cases per 100,000 in 1999.4 The increase is likely a result of several factors, including increased exposure to ultraviolet (UV) radiation and, possibly, earlier detection of melanoma.5 From 1973 to 1999, the number of melanoma deaths also rose: Annual deaths per 100,000 people from melanoma increased by about 40% during this period, from 1.9 to 2.7 per 100,000 people. During the past 10 years, however, melanoma mortality rates have remained relatively stable among women, but less so among men.3, 6, 7 (Mortality rates for white males by economic area are presented in Figure 1.)
Section snippets
Excessive exposure to UV radiation
High levels of exposure to UV radiation increase the risk of all three major forms of skin cancer, and approximately 65% to 90% of melanomas are caused by UV exposure.8 Studies have shown that the damage caused by UV radiation, particularly damage to DNA, plays a central role in the development of melanoma.9 Risk of melanoma and other skin cancers can therefore be reduced by limiting exposure to sunlight, which is the primary source of UV radiation. (Sunlamps and tanning beds are other
Skin color and ethnicity
Although anyone can get skin cancer, people with certain characteristics are particularly at risk. Whites are 80 times more likely to develop basal cell and squamous cell carcinoma than African Americans,28 and 20 times more likely to develop melanoma.29 Hispanics appear to be at lower risk of melanoma than non-Hispanic whites: a study conducted in Los Angeles found Hispanic incidence rates to be 2 to 3 per 100,000, whereas the rate for non-Hispanic whites is 11 per 100,000.30 According to the
Environmental factors affecting UV radiation
Environmental factors that increase the amount of UV exposure include proximity to the equator; higher altitude; lower levels of cloud coverage (which can allow up to 80% of UV rays to penetrate the atmosphere); the presence of materials that reflect the sun, such as pavement, water, snow, and sand; exposure to the sun around midday; and spending time outside in the spring or summer.30, 40 Ozone depletion could potentially increase levels of solar radiation at the Earth's surface.30, 41
Sun-protective behaviors
Behaviors that reduce skin cancer risk include limiting or minimizing exposure to the sun during peak hours (10 a.m. to 4 p.m.) because UV rays are more intense around midday, wearing protective clothing, or using appropriate sunscreen protection.
Scientific knowledge about sunscreen has undergone some recent evolution. Although sunscreen is thought to be an important adjunct to other types of UV protection, it should not be counted on to provide UV protection by itself. Sunscreen clearly
Prevalence of sun-protective behaviors
In 1992, a total of 53% of U.S. adults were “very likely” to protect themselves from the sun by practicing at least one protective behavior (sunscreen, wearing clothing, or seeking shade).54 Less than one third of white adults used sunscreen (32%), sought shade (30%), or wore protective clothing (28%). Among African Americans, 28% wore sun-protective clothing and 45% sought shade, but only 9% used sunscreen.55 The sun-protective behaviors of both whites and African Americans were more common
The Guide to Community Preventive Services
The systematic reviews in this report represent the work of the independent, nonfederal Task Force on Community Preventive Services (the Task Force). The Task Force is developing the Guide to Community Preventive Services (the Community Guide) with the support of the U.S. Department of Health and Human Services in collaboration with public and private partners. The Centers for Disease Control and Prevention (CDC) provides staff support to the Task Force for development of the Community Guide. A
Healthy People 2010 goals and objectives for preventing skin cancer
The interventions reviewed in this article may be useful in reaching the objectives set in Healthy People 201060:
- 1
Increase to 75% the proportion of people who use at least one of the following protective measures that may reduce the risk of skin cancer: avoid the sun between 10 a.m. and 4 p.m., wear sun-protective clothing when exposed to the sun, use sunscreen with a sun-protection factor (SPF) of ≥15, and avoid artificial sources of ultraviolet light.
- 2
Reduce melanoma deaths to <2.5 per 100,000
International Agency for Research on Cancer
In 2001, the International Agency for Research on Cancer (IARC), an independent organization supported by the World Health Organization, convened a work group to address sunscreen use. The work group made the following recommendations:50
- •
Protect the skin from solar damage by wearing tightly woven protective clothing that adequately covers the arms, trunk, and legs, and a hat that provides adequate shade to the entire head; seeking shade whenever possible; and avoiding outdoor activities during
Methods for conducting the review
The general methods used to conduct systematic reviews for the Community Guide have been described in detail elsewhere.63, 64 The specific methods for conducting this review, including selection of interventions and outcomes and the search strategy for interventions to increase sun-protective behaviors, are presented in Appendix A. The conceptual approach to the review, critical both for describing the methods and for understanding the results of the review, is described below.
Educational and policy interventions in child care centers
Interventions in child care settings involve efforts to promote sun-protective behaviors among children aged <5 years who attend programs in these settings. These interventions include at least one of the following: (1) provision of information directly or indirectly to the children (through instruction or small media education); (2) additional activities to influence children's behavior (modeling, demonstration, or role playing); (3) activities intended to change the knowledge, attitudes, or
Mass media campaigns alone
Mass media campaigns can promote sun-protective behaviors in a community. They provide information through mass media (e.g., television, radio, newspapers, magazines, and billboards), and can also include small media (e.g., brochures, flyers, newsletters, informational letters, and posters). Mass media has been widely used in public health programs to address behavioral risk factors, and is a recognized vehicle for reaching wide audiences, particularly for the purpose of raising awareness and
General research issues
Although the effectiveness of two recommended interventions (i.e., interventions in primary schools for improving children's covering-up behaviors and interventions in recreational or tourism setting for improving adult covering-up behaviors) for reducing the risk of skin cancer has been established, important general research issues remain, some of which have been identified in previous literature.22, 65, 239, 240, 241, 242 The most important and surprising conclusion is that, despite all the
Theory, conceptual models, and evidence for planning interventions
Like other types of health promotion efforts, skin cancer prevention programs are most likely to succeed when they are based on a clear understanding of the targeted health behaviors and their environmental context. Theories about why people do or do not engage in sun-protective behaviors, and data about a given target audience (e.g., about a particular population's barriers to and facilitators of sun protection) are often helpful in guiding the search for promising and suitable interventions.
Research needs and work in progress
The field of behavior change for skin cancer prevention has progressed significantly in the past decade, but important areas for further advancement exist. As outlined above, these include design, measurement, better description of interventions, development of a better understanding of how environmental and policy interventions work, and studies in multiethnic populations. The use of new communication technology and international collaborations can make significant contributions in these
Summary: Findings of the Task Force on Community Preventive Services
The Task Force recommends two interventions to improve sun-avoidance or covering-up behaviors: educational and policy interventions in primary schools, and programs for adults in outdoor recreational or tourism settings. These Task Force recommendations represent tested interventions that promote decreased UV exposure at the community level. They can be used for planning interventions to promote UV protection or to evaluate existing programs. The other interventions that were reviewed, but for
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Notes: Affiliation reflects author's location while this research was being conducted. Names and affiliations of Task Force on Community Preventive Services members are listed at www.thecommunityguide.org.