Skin cancer prevention : behaviours related to sun exposure and early detection

Abstract

Skin cancer is an emerging public health problem in Sweden. Even though the most important risk factor for the development of skin cancer - sun exposure - is known, the incidence of skin cancer is still increasing. Every year approximately 30,000 people in Sweden are diagnosed with skin cancer and approximately 400 die of this condition. In addition to the deaths and suffering caused by skin cancer, its treatment incurs considerable health costs.

The aim of this thesis was to examine factors relevant to sun-related behaviours and early detection of malignant skin lesions. The preventive effects of two information strategies on sun-related behaviours and early detection of malignant melanoma were also studied.

Three samples were studied with questionnaires, these were: 52 female nurses attending a postgraduate course in research methodology at the Karolinska Institutet, 2,615 adolescents (13, 15 and 17 year of age) randomly selected from the population in Sweden, and 1,743 adults (18-37 year of age) randomly selected from the population in Stockholm County. The first sample completed the questionnaires in connection to lectures, whereas the other two responded to mailed questionnaires. Further, 90 patients recruited from the Karolinska hospital and 30 randomly selected persons from Stockholm County (18 to 79 year of age) participated in an interview study.

The results showed that the questionnaires commonly used to measure sun-related behaviours had sufficient reliability. The studies confirm previous findings that adolescents and adults in Sweden spend a lot of time in the sun, frequently with the intention of becoming tanned, and frequently become sunburnt. The studies also highlighted variables associated with sun-related behaviour. Knowledge about skin cancer was not associated with decreased sunbathing or increased sun protection behaviour among adolescents. In fact, high knowledge was positively related to frequent sunbathing. Positive attitudes towards sunbathing and having a tan were strongly related to exposure to solar radiation. Being around people who frequently sunbathe was related to intentional tanning and vacation to sunny resorts. To perceive sun exposure as risky increased the likelihood of intending to decrease sunbathing and undertake sun protection behaviour. Perceived control over the risks with sun exposure was associated with sun protection behaviour among women.

An individual ultraviolet (UV) radiation intensity indicator and information about the UV index (a measure of the intensity of solar radiation) did not affect sun-related behaviour more than general written information about sun protection. Health care providers seem to play an important role in early detection of malignant melanoma, as more than 1/3 of the melanoma patients interviewed said that their melanoma was detected at a visit to a physician for another reason. The ABCD criteria (a description of the characteristics of early melanoma) seem to increase laymen's ability to make adequate judgements of skin lesions and could be used in secondary preventive interventions.

The results of the present thesis contribute to the understanding of factors relevant to sun-related behaviours. Taking these factors into account when planning skin cancer prevention activities may improve the effectiveness of these efforts.