Article

Risk Factors for Malignant Melanoma and Preventive Methods

Cutis. 2014 November;94(5):241-248

UV radiation is an important environmental risk factor for cutaneous melanoma; however, information concerning UV exposure in many populations is lacking. The aim of our study was to investigate risk factors for malignant melanoma (MM), particularly those related to UV exposure behavior in the Czech Republic and Germany. This case-control study included 207 patients who were consecutively diagnosed with MM in 2 dermatology clinics in Prague, Czech Republic, and Munich, Germany. Controls were 235 patients with other dermatologic conditions. All 442 participants completed a questionnaire on sociodemographic data and factors related to UV exposure. The association between risk factors and MM was assessed using multivariate logistic regression. Patients with Fitzpatrick skin types I and II had a higher likelihood of developing melanoma than those with Fitzpatrick skin type III. Frequent sunburns during childhood and adolescence were strongly related to developing melanoma. A higher level of education also was associated with a higher melanoma incidence. Variables related to UV exposure were strongly associated with melanoma in our study population. Prevention campaigns should be implemented to improve awareness of melanoma to reduce exposure to UV radiation among high-risk patient populations.

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Practice Points

Our study revealed the following common risk factors associated with higher melanoma incidence: light eye color (ie, blue, green, gray), Fitzpatrick skin types I and II, frequent sunburns during childhood and adolescence, and higher level of education.
Prevention campaigns should be implemented to improve awareness of melanoma to reduce exposure to UV radiation among high-risk patient populations.

References

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Cutaneous melanoma is a malignant tumor of the skin that develops from melanin-producing pigment cells known as melanocytes. The development of melanoma is a multifactorial process. External factors, genetic predisposition, or both may cause damage to DNA in melanoma cells. Genetic mutations may occur de novo or can be transferred from generation to generation. The most important environmental risk factor is UV radiation, both natural and artificial. Other risk factors include skin type, ethnicity, number of melanocytic nevi, number and severity of sunburns, frequency and duration of UV exposure, geographic location, and level of awareness about malignant melanoma (MM) and its risk factors.¹

Melanoma accounts for only 1% to 2% of all tumors but is known for its rapidly increasing incidence.² White individuals who reside in sunny areas of North America, northern Europe, Australia, and New Zealand seem to be at the highest risk for developing melanoma.³ The global incidence of MM from 2004 to 2008 was 20.8 individuals per 100,000 people.⁴ In Central Europe, 10 to 12 individuals per 100,000 people were diagnosed with melanoma, and 50 to 60 individuals per 100,000 people were diagnosed in Australia. In 2011, the lifetime risk of being diagnosed with melanoma was 1% in Central Europe and 4% in Australia.² The incidence of melanoma is lower in populations with darker skin types (ie, Africans, Asians). In some parts of the world, the overall incidence and/or severity of melanoma has been declining over the last few decades, possibly reflecting improved public awareness.⁵

Cutaneous MM is an aggressive skin cancer that has fatal consequences if diagnosed late. Chances of survival, however, increase dramatically when melanoma is detected early. Collecting and analyzing data about a certain disease leads to a better understanding of the condition and encourages the development of prevention strategies. Epidemiologic research helps to improve patient care by measuring the occurrence of an event and by investigating the relationship between the occurrence of an event and associated factors; in doing so, epidemiologic research directly enables a better understanding of the disease and promotes effective preventive and therapeutic approaches.⁶

Although risk factors for melanoma are well established, current epidemiologic research shows that information on UV exposure and its association with this disease in many parts of the world, including Central Europe, is lacking. The aim of this study was to investigate behavioral and sociodemographic factors associated with the development of MM in the Czech Republic and Germany.

Materials and Methods

This hospital-based, case-control study was conducted in the largest dermatology departments in the Czech Republic (Clinic of Dermatology and Venereology, Third Faculty of Medicine, Charles University, Prague) and Germany (Department of Dermatology and Allergology, Ludwig Maximilian University, Munich). Data from the Czech Republic and Germany were not evaluated separately. These 2 countries were chosen as a representative sample population from Central Europe.

Study Population

The study population included 207 patients (103 men; 104 women) aged 31 to 94 years who were consecutively diagnosed with MM (cases). Patients with acral lentiginous melanoma were excluded from the study due to the generally accepted theory that the condition is not linked to UV exposure. Melanoma diagnosis was based on histopathologic examination. The study population also included 235 randomly selected controls (110 men; 125 women) from the same 2 study centers who had been hospitalized due to other dermatologic diagnoses with no history of any skin cancer. Among patients asked to take part in the study, the participation rates were 83% among cases and 62% among controls.

Assessment

Various sociodemographic factors and factors related to UV exposure were assessed via administration of a structured questionnaire that was completed by all 442 patients.

Four statistical models concerning variables were constructed. The basic model, which was part of all subsequent models, included age, sex, education, and history of skin tumors. Variables included in the biological model were eye color (light vs dark) and Fitzpatrick skin type (I–V). Variables included in the lifestyle model were the use of sunscreen (never and rarely; often; always; always and repetitively), sun exposure during work (yes/no), and seaside vacation (never, rarely, regularly, more than once per year). The variable in the exposure model was the number of sunburns during childhood and adolescence (none, 1–5 times, 6–10 times, ≥11 times).

Sociodemographic characteristics (sex, age, education) and prior incidence of skin tumor were included in each model. Although there were no statistically significant differences in the incidence of melanoma associated with sex and age, those variables were kept in the models to control the impact of other variables by sex and age.

Other variables were added into the model one by one, and the likelihood ratio was tested step-by-step. Only the variables that improved the model fit were kept in the final model. Impact of variables on dependent variables also was tested; variables with no significant impact on dependent variables were left out of the model.

Statistical Analysis

The association between risk factors and MM was assessed using multivariate logistic regression. In total, 4 models were included in the results, which were presented as odds ratios (ORs) and 95% confidence intervals (CIs). A significance level of α=.05 was chosen. The statistical program Stata 11 was used for all analyses.

Results

Descriptive data on the 442 patients surveyed are shown in Table 1. The results of the logistic regression in all studied models are shown in Table 2.