Sun behavior drives melanoma risk

To counter a dearth of information regarding occupational sun exposure in Europe, researchers examined nearly 1,500 employees of the Austrian Mineral Oil Company (OMV), an international company that produces more than 80 percent of the gasoline used in Austria. The sample included office-based employees, as well as those who work in refineries and at drilling sites.

Robert Strohal, M.D., associate professor of dermatology and head of the department of dermatology and venereology at the Federal University Teaching Hospital of Feldkirch, Austria, says, "We looked at typical skin-related melanoma risk factors dermatologists can see and define, including the number of nevi and the amount of pre-Clark nevi that fulfill one of the ABCD criteria."

Dr. Strohal says that after researchers conducted multivariate analysis involving some 150,000 parameters in total, "in general, the amount of dysplastic nevi was in accordance with the literature - about 5 percent," whether one looked at skin- or activity-related risk factors.

Office vs. outdoor workers

Researchers furthermore compared the impact of skin-related risk factors between office and outdoor workers, as well as those who performed both functions.

"To our astonishment," he says, "we did see more sun-related skin damage in outdoor workers. There were higher numbers in terms of trends, but they didn't reach statistical significance. For example, we found 11.3 percent of outdoor workers showed severe sun-related skin damage, versus 10 percent of office workers."

Analysis of leisure activities, however, revealed substantial and clinically significant differences between office workers and outdoor workers. Specifically, 18 percent of office workers frequently spent leisure time outside, versus 28 percent of outdoor workers.

Conversely, holidays in Europe's sunny southern regions were quite rare among outdoor workers but common among more affluent indoor workers. However, 21 percent of office workers reported using sun creams frequently, compared to just 8 percent of outdoor workers.

Attempting to determine which risk factors mattered most, researchers first found a strong positive correlation between sun-related skin damage and number of nevi (Bauer J et al. Int J Cancer. 2005 Apr 22; [Epub ahead of print].). Among relevant risk factors for melanoma, key factors among workers examined included sun bed use 13 to 20 times yearly and vacationing in the South more than once yearly.

"Sun cream and textile protection didn't seem to help much," Dr. Strohal adds. "Those who most seldom used sunscreen had the lowest melanoma risk rate (2 percent as measured by skin signs.) Among workers who used sunscreen extremely often, 10 percent showed melanoma risk signs on their skin." The study cited in the preceding paragraph reinforces this finding.

Dr. Strohal surmised that perhaps frequent sunscreen users possess a false sense of security and spend extensive amounts of time in the sun. Alternately, respondents who spend inordinate amounts of time in the sun may overstate their sunscreen use when answering researchers' questions.

Researchers also considered public health implications of their findings, perhaps most notably the discovery that 44 percent of respondents had never had their moles checked by a dermatologist. In contrast, 5.7 percent of workers reported regularly visiting dermatologists for this purpose.

Disclosure: Dr. Strohal reports no financial interests relevant to this article.

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