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Melanoma: can the sun be protective?

Melanoma: Can the sun be protective?

It's that season when sunbathers by the droves seek to soak up some rays, largely ignoring dermatologists' strenuous warnings against intentionally baking up a tan. The concern is over melanoma -- a virulent skin cancer whose incidence appears to have practically doubled since 1980 (SN: 12/17/88, p. 396). Though understanding of melanoma's cause is cloudy at best, sun exposure appears to play a role in the development of at least some of these deadly skin cancers -- which annually claim about 6,000 U.S. lives. However, one new study appears to challenge the blanket prescription that everybody cover up. It suggests those who bronze easily may actually derive some melanoma protection from a moderate tan.

Neil Dubin and colleagues at New York University Medical Center surveyed the sun-exposure history of 289 melanoma patients and 527 adults with noncancerous skin problems. Their data show that those who worked "mostly outdoors" had nearly twice the melanoma risk as those who worked "mostly indoors." However, "partly outdoor" work appeared "somewhat protective" of melanoma risk among those who tan easily. The same was not true for those having a poor ability to tan. Partly outdoor work increased their melanoma risk by 50 percent, and mostly outdoor work more than tripled their risk, when compared with those who worked indoors. Similarly, among the easy tanners, a mix of indoor and outdoor recreation appeared to offer some protection against melanoma. Among the hard-to-tan crowd, mixing indoor and outdoor recreation was no more protective than playing indoors only.

Overall, the chronic and intermittent sun-exposure data suggest "that moderate sun exposure may actually protect against melanoma" in those who tan easily, the authors write in the newly released May ENVIRONMENTAL HEALTH PERSPECTIVES. For poor tanners, however, the more sun they got, the higher their risk of melanoma. But age also proved important. Cumulative sun exposure was linked to melanoma risk -- but only in those over age 60. Meanwhile, those aged 20 to 40 who had ever gotten a blistering burn faced a melanoma risk 5.6 times that of those who never had. Older individuals, however, faced no increased risk from any blistering sunburns.

In general, these findings are "typical" of several major studies, notes Boston University dermatologist/oncologist Howard K. Koh. However, he believes, it's still too early to know whether the newly identified apparent protective effect from tanning is real. Even if it is, he notes, the magnitude of protection reported -- 20 percent -- is quite small.
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Title Annotation:Biomedicine
Publication:Science News
Date:Jul 8, 1989
Previous Article:Expert system homes in on forest foes.
Next Article:Leg moles? Get out the sunblocker.

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