LOTIONS MAY NOT BLOCK CANCER.

Byline: David R. Baker Daily News Staff Writer

The sunblock that people wear as a shield against Southern California's relentlessly sunny days might not help prevent the deadly skin cancer melanoma, according to a controversial presentation Tuesday.

Speaking at a meeting of the American Association for the Advancement of Science in Philadelphia, a researcher with one of the country's top cancer centers said she found no connection between the use of sunscreen lotions and the incidence of melanoma.

And she questioned the conventional wisdom that sunburn can cause melanoma, which struck about 40,000 people nationwide last year and killed about 7,300 of them.

Those findings were greeted with skepticism by Los Angeles dermatologists and fair-skinned people, trained since childhood to smear on sunscreen or face the painful, blistering consequences.

``If you ask any good dermatologist, or even a bad dermatologist, how they're going to protect their skin going outside - they're going to use sunscreen,'' said Dr. Dan Gross, clinical professor of dermatology at the University of California, Los Angeles.

Researcher Marianne Berwick of the Memorial Sloan-Kettering Cancer Center in New York said people still should use sunscreens because they can stem some damage caused by the sun. But their ability to ward off the onset of skin cancer, she said, has not been proved.

``They do a terrific job of preventing sunburn. They may prevent photo-aging,'' Berwick said. ``But we don't know whether they can help prevent melanoma.''

People who wear sunscreen but still contract cancer could be lulled into a false sense of security by the lotion, Berwick said. Believing themselves protected, they stay in the sun too long and don't get the sunburn that would otherwise warn them to seek out shade, she said.

``People shouldn't use sunscreens in place of common sense,'' Berwick said.

That point, at least, drew unanimous agreement from dermatologists.

``Obviously, if you put on sunscreen, sit out in the desert and bake for a few hours, it isn't going to help you,'' said UCLA dermatologist and plastic surgeon Vincent Hung.

The question isn't merely academic.

Melanoma struck about 40,000 people nationwide last year. Between 1973 and 1993, the death rate for melanoma increased 48 percent among American men, according to the federal Centers for Disease Control and Prevention in Atlanta.

The latest figures available from California's Department of Health Services show 887 new cases reported in Los Angeles during 1994, up from 809 cases the year before.

For some Los Angeles residents, sunscreen is part of their regular routine - and will be, regardless of Berwick's findings.

Kindergarten teacher Marcella Peters of Northridge uses it when in-line skating. But she said Tuesday that she never thought sunscreen could prevent cancer by itself.

``A lotion alone won't protect you,'' Peters said. ``You need a hat as well.''

Sherman Oaks resident Julie Tice said she will continue to use the lotions when heading outside.

``But I'll be staying out of the sun more because of this study,'' she said Tuesday, as her dogs dragged her around Lake Balboa.

Despite the disagreement about sunscreens' effectiveness, several of Berwick's key findings are consistent with what doctors had long believed about skin cancer.

The risk of contracting melanoma was about six times greater for people with light skin, hair and eyes than it was for people with darker features, Berwick found. Similarly, people with many moles had six times the risk as people with few or no moles.

Berwick also found that people who regularly spent time in the sun faced less risk than those with just sporadic exposure to sunlight. Frequent exposure, she said, literally thickened the skin and strengthened the body's defenses against sun damage.

TIPS TO AVOID MELANOMA

Despite new questions about the effectiveness of sunscreen, the Centers for Disease Contro`l and Prevention recommend these steps for avoiding skin cancer:

Reduce direct exposure to the sun, especially between 10 a.m. and 4 p.m.

When outdoors, wear a broad-brim hat, long-sleeve shirt, long pants and sunglasses.

Use sunscreen lotion with a sun protection factor of at least 15.

Avoid artificial sources of ultraviolet light, such as tanning beds and sunlamps.

Refer to the daily UV Index in your local weather forecast when planning outdoor activities. A UV Index level of 5 is considered moderate.

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Box: Tips to avoid melanoma (see text)