Risk Factors for Malignant Melanoma and Preventive Methods

Comment

In this study, we concentrated on UV exposure and various sociodemographic factors that were possibly connected to a higher risk for developing melanoma. We observed that the majority of patients in the melanoma group had achieved a higher level of education than the control group. Most of the melanoma group patients had light-colored eyes and spent more time in direct sunlight at work. Although seaside vacations did not correlate with a higher occurrence of melanoma, it was noted that the melanoma patients used sunscreen much less often than the control group. Major differences among respondents in the melanoma group versus the control group were seen in the reported number of sunburns sustained in childhood and adolescence. More sunburns during these periods seemed to play the most important role in the risk for melanoma. Some of the patient responses to the questionnaire may be biased, as respondents answered the questions by themselves.

Because risk factors for and preventive methods against melanoma are well established, one would assume that general knowledge regarding melanoma is adequate. On the contrary, it has been shown that knowledge about melanoma is insufficient, even among professionals and individuals with higher levels of education. In a study based on a questionnaire administered to plastic surgeons, only 37.5% (27/72) of respondents correctly identified the duration of action of sunscreen to be 3 to 4 hours.⁷ Approximately half of the respondents (37/72) did not know that geographical conditions such as altitude and latitude as well as shade can alter sunscreen efficacy and also were not aware of the protective action of clothing. These results are alarming and indicate that even medical professionals, who should play a main role in improving the health knowledge of the general population, have an unsatisfactory level of education in prevention of melanoma. Another important part of better education of specialists treating skin disorders is good knowledge of dermatoscopy. In fact, the Annual Skin Cancer Conference 2011 in Australia emphasized the importance of dermatoscopy in primary and secondary prevention of skin cancer.⁸ Teaching dermatoscopy should be part of melanoma campaigns for professionals.

Our basic model demonstrated that a higher level of education was connected to a higher occurrence of MM, which may seem surprising, considering that most diseases, along with their incidence, prevalence, and mortality, usually are associated with lower levels of education or lower socioeconomic status. A similar trend also was reported in prior studies, with higher socioeconomic groups showing higher incidences of cutaneous melanoma; colon cancer; brain cancer in men; and breast and ovarian cancer in women. Additionally, patients with higher socioeconomic status have been shown to have a survival advantage.⁹ Individuals with higher socioeconomic status can afford to travel more often for vacation and are more frequently exposed to direct sun. Individuals with higher levels of education also are generally more aware of the importance of disease prevention and therefore go for preventive checkups more often. The detection of melanoma in this socioeconomic group should be higher.

Our biological model demonstrated that respondents with lighter eyes had melanoma almost 3 times more often than individuals with darker eyes. Fitzpatrick skin types I and II also were significantly associated with the development of melanoma (P<.001). These findings are generally confirmed in the literature. In a study of the incidence of melanoma in Spain, statistically significant risk factors included blonde or red hair (P=.002), multiple melanocytic nevi (P=.002), Fitzpatrick skin types I and II (P=.002), and a history of actinic keratosis (P=.021) or nonmelanoma skin cancer (P=.002).¹⁰ A group in Italy also has investigated the main risk factors for melanoma. This study suggested dividing patients into high-risk subgroups to help minimize exposure to UV radiation and diagnose melanoma in its early stage.¹¹

The results from our study confirmed the importance of concentrating melanoma prevention campaign efforts on high-risk patients. Dividing these patients into subgroups (eg, individuals who play outdoor sports, individuals with occupations associated with UV exposure, individuals who use indoor tanning beds, individuals with a family history of melanoma) may be helpful. A case-control study on sun-seeking behavior in the Czech Republic showed that the most alarming risk factors were all-day sun exposure during adolescence, frequent holidays spent in the mountains, and inadequate use of sunscreen in adulthood.¹² We investigated the effects of sunscreen use on the incidence of melanoma in our lifestyle model and discovered that it decreased the risk for melanoma. Respondents who used it always had a much lower risk for developing melanoma than those who never or rarely applied it. Individuals who used sunscreen always and repetitively (ie, more than once per period of sun exposure) did not show a lower risk than those who used it once per period of sun exposure. This finding could mean that patients who are known to get sunburns or who feel a certain discomfort on direct exposure to the sun tend to use sunscreen always and repetitively.

It is important to note that some investigators disagree with the importance of some generally accepted means of prevention, such as the effect of sunscreen products. Due to insufficient evidence, the role of sunscreen use in reducing the risk for skin cancer, especially cutaneous MM, is controversial.¹³ Although we could prove there is a considerable difference in the incidence of melanoma in patients who claimed to use sunscreen always versus those who never use it, we agree that more evidence on this topic is needed. Furthermore, it has been reported that risk for melanoma has increased with rising intermittent sun exposure and indoor tanning bed use.^14,15

Respondents who regularly traveled to seaside regions showed a surprisingly lower incidence of melanoma than respondents who did not spend their vacations in seaside locations. It is possible that individuals who choose not to spend their vacations at the seaside are more prone to sunburns and therefore do not prefer to spend their free time in direct sunlight. Another possible explanation is that individuals who regularly travel to seaside regions actively try to protect themselves from sunlight and sunburns. A higher incidence of melanoma also was observed in respondents who reported sun exposure during work.

In our exposure model, we demonstrated that a history of sunburns is the strongest risk factor for melanoma. Frequent sunburns during childhood and adolescence were strongly associated with the development of MM. This association has been supported in a systematic review on sun exposure during childhood and associated risks.¹⁶

Conclusion

To improve patient knowledge about melanoma prevention, we suggest directing targeted campaigns that address high-risk population groups, such as individuals with red hair and/or light eyes, people with an occupation associated with frequent UV exposure, and individuals with higher levels of education. With regard to younger populations, parents as well as physicians and teachers should be aware that frequent sunburns during childhood and adolescence and use of tanning beds are 2 main risk factors for MM.