Sun Exposure And Skin Cancer Research Paper

1. Skin Cancer: Incidence And Causation

The two major classes of skin cancer are malignant melanoma (MM) and nonmelanoma skin cancers (NSC; subtypes: basal cell carcinoma, squamous cell carcinoma). In many countries, skin cancer is the cancer with the most rapidly increasing incidence rate. In the United States, the incidence rates of skin cancer are 12.0 per 100,000 Caucasians for MM (mortality rates: men 3.3 per 100,000 people/year, women 1.7) and 236.6 per 100,000 Caucasians for NSC (mortality rates: men 0.7, women 0.3) (Marks 1995). Incidence rates for people with darker skin are much lower.

The development of skin cancer depends on constitutional and environmental factors (for an overview, see Marks 1995). The major constitutional factors are skin color, skin reaction to strong sunlight, and, additionally for MM, large numbers of moles, freckles, and family history of MM. The major environmental risk factor for skin cancer is sun exposure. Cumulative sun exposure is related to the development of NSC. For MM, the role of sun exposure is less clear. Increased risk of MM seems to be related to severe sunburns, in particular in childhood, and intermittent recreational sun exposure.

2. Predictors Of Sun Exposure

Sun exposure not only accompanies many working and recreational outdoor activities, it is also seeked intentionally (for an overview of studies on psychosocial factors of sun exposure, see Arthey and Clarke 1995, Eid and Schwenkmezger 1997). The major motivational predictor for unprotected sun exposure is the desire for a suntan. Level of suntan is related to the perception of other people as being healthy and attractive in a curvilinear manner, with a medium tan considered the healthiest and most attractive skin color. Therefore, getting a suntan helps people to make a good impression on others. The belief that a suntan improves one’s physical appearance is the strongest predictor of suntanning. Voluntary sun exposure is related to thinking more about one’s physical appearance, to a higher fear of negative evaluations by others, and to a higher body self-consciousness and body self-esteem. In addition to these variables of personal appearance, suntanning is related to a positive attitude toward risk taking in general and to having friends who sunbathe and use sunbeds.

3. Predictors Of Sun Protection Behavior

The harmful effects of UVR on the skin can be prevented by sun protection behavior. The four most important protection behaviors are: (a) Avoiding direct sunlight, particularly during the peak hours of daylight (10 am to 4 pm), (b) seeking shade, (c) wearing a hat, (d) wearing skin-covering clothing, and (e) using sunscreen with a sun protection factor of at least 15. Even in high-risk countries such as Australia, the prevalence rates of these protective behaviors are rather low indicating that about half of the population are inadequately protected on sunny days (e.g., Lower et al. 1998). Voluntary sun exposure and the use of sun protection are two largely independent and only weakly correlated behaviors. Moreover, the predictors for sun protection behavior differ from the predictors for sun exposure. In contrast to sun exposure, appearance-oriented variables are less important for predicting sun protection behavior. The major predictors for sun protection behavior are perceived threat of skin cancer, the benefits and barriers of different sun protection behaviors, social factors, and knowledge about skin cancer (Eid and Schwenkmezger 1997, Hill et al. 1984).

Perceived threat of skin cancer depends on the perceived severity of and the vulnerability to skin cancer. People who rate skin cancer as a severe disease and who think that they are more vulnerable to skin cancer are more likely to use sun protection. Furthermore, individuals with a sensitive and fair skin, both which are more prone to skin cancer, use sun protection more often. This risk perception is strongly related to gender. Women have stronger vulnerability and severity beliefs. Moreover, women use sunscreen more often and apply sunscreen with a higher sun protection factor than men.

The actual display of specific sun protection behaviors depends on (a) the belief that these behaviors are effective in preventing skin damage, sunburns, and skin cancer, and (b) the specific barriers of each behavior (Hill et al. 1984). Specific barriers to the application of sunscreen is the belief that sunscreen is greasy and sticky and the fact that sunscreen has to be applied repeatedly. An additional barrier for men is the belief that sunscreen makes men appear seemingly sissy and looks unattractive. Barriers against wearing hats are the beliefs that hats are inconvenient to wear as well as causes problems with hairstyle. Additionally, for men, wearing a hat is associated negatively with the beliefs that wearing a hat causes baldness and a sweaty head, is inconvenient on windy days, and gets in the way when playing sports. The major barriers against wearing shirts are the discomfort from heat and the feeling of being overdressed. Therefore, a goal of skin cancer prevention programs must be the removal of these specific barriers against sun protection behavior. Because these barriers partly depend on temporary fashion influences, the present-day barriers of specific sun protection behaviors have to be examined before a prevention campaign is planned.

Social factors also have an important influence on sun protection. Use of sun protection is correlated with peers’ sun protection behavior, parental influence, and parental sun protection behavior. Furthermore, people who know a person suffering from skin cancer use sun protection more often. Finally, knowledge about the risks of sun exposure has been proven a significant predictor for sun protection in many studies. In particular, people with more knowledge about skin cancer use sunscreen with a higher sun protection factor.

4. Skin Cancer Prevention

With respect to the target groups considered, sun exposure and sun protection modification programs can be grouped into three classes: (a) programs using mass media, (b) community intervention programs, and (c) educational programs (for an overview of these programs, see Eid and Schwenkmezger 1997, Loescher et al. 1995, Morris and Elwood 1996, Rossi et al. 1995).

4.1 Mass Media Programs

Typical mass media programs use informational pamphlets, comic books, newspaper reports, TV and radio advertisements, or videotapes to carry their messages. These mass media campaigns are either often not evaluated, or the evaluations are published in reports that are not accessible to the public, or the evaluations suffer from methodological problems (e.g., missing control group). However, there are some studies evaluating single videotapes or informational pamphlets by an experimental or control-group design (for an overview see Eid and Schwenkmezger 1997, Morris and Elwood 1996). According to these studies, videotapes and informational pamphlets can increase knowledge about, perceived severity of, and vulnerability to skin cancer, as well as increase individual sun protection intentions. Studies focusing on long-term effects on behavior, however, are missing. Furthermore, these studies show that an emotional prevention video imparting knowledge by employing a person with skin cancer might be more appropriate than a more unemotional presentation of facts. Moreover, educational texts focusing on the negative effects of sun exposure for physical appearance (wrinkles, skin aging) might be more appropriate than texts on the negative health-related consequences. This, however, might only be true for people with a low appearance orientation, whereas appearance-based messages can result in boomerang effects for high appearance oriented people. Finally, the manner in which a health message is framed is important. Detweiler et al. (1999) demonstrated that messages on sun protection behavior are more effective when they highlight potential positive effects of the displayed sun protection behavior (gain-framed messages) than when they focus on the negative effects of the omitted behavior (loss-framed messages).

4.2 Community Intervention Programs

Mass media are often a component of community intervention programs, but community intervention programs can implement several other methods as well. Community-based programs can make use of local peculiarities (e.g., the daily UVR rate in a community) and can focus on local places of risk behavior, for example, swimming pools and beaches. Based on principles of learning theory, Lombard et al. (1991) designed an intervention program with pool lifeguards as models for sun protection behaviors and daily feedback posters of the sun protection behavior displayed the day before. This program was effective with respect to two sun protection behaviors (staying in the shade, wearing shirts) but not other ones. Rossi et al. (1995) describe several new techniques such as special mirrors (sun scanner) and photographs (sun damage instant photography) that have been used in intervention programs on beaches to show the effects of sun damage and photoaging in a more dramatic fashion.

4.3 Educational Programs

Because of the cumulative risk of sun exposure and the risks of sunburn in childhood, intervention programs are particularly important for children and adolescents. Educational programs have been developed for students of different ages from preschool to high school. In general, these programs are effective in enhancing knowledge about skin cancer and the awareness of the risks of unprotected sun exposure. Changing attitudes toward sun protection, however, have only been found after participation in programs consisting of more than one session. With respect to changes in behavioral intentions the results are inconsistent. Significant changes in intentions have been found in only a few studies and not consistently across the intentions to different behaviors. Changes in observed behavior, however, have not been analyzed. The failure of educational programs in changing behavioral intentions might be due to the fact that these programs have focused more on motivational than on behavioral factors. Multimethod educational programs including components on the implementation of behavioral routines that are very important for developing health behavior in childhood are desiderata for future research.

5. Future Directions

Sun exposure and skin cancer prevention are relatively new fields of research. Future research will profit from the use of multimethod assessment strategies of behavior that does not only assess self-reported behavioral intentions but also uses observational and physical measures of behavior (e.g., spectrophotometers for measuring the melanin skin content). Furthermore, research on new components of intervention programs is needed. For example, future programs could consist of behavior change methods in addition to attitude change methods as well as strategies for weakening the association between suntan and attractivity.

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