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Applying a screen with an SPF of 15, for example, wards off reddening of the skin 15 times longer than would be the case without any protection. That would seem long enough, and some dermatologists have suggested that using higher SPFs is unnecessary. But Dr. Kays Kaidbey, a dermatologist at the University of Pennsylvania, has found that microscopic changes occur in the skin even when sunburn has been prevented. Writing in the Journal of the American Academy of Dermatology, Kaidbey reported that screens with SPFs of 30 are more effective than those with 15 ratings in preventing those changes.
Despite the growing publicity about skin cancer and sunscreens, untold numbers of Americans have either missed or are ignoring the message and are still exposing themselves needlessly to the sun. A glaring example: the San Francisco Bay Guardian, a weekly newspaper that annually publishes a list of Northern California nude beaches, proudly revealed last month that its listing had grown from 21 beaches in 1976 to 69 this year. Other Americans continue to sunbathe wearing next to nothing. "Our society has placed an enormous value on being tan, equating it with health, youth, beauty and success," says Dr. Susan Blumenthal, chief of the National Institute of Mental Health's behavioral medicine program. "It will take at least a couple more years before we see a drastic change in societal attitudes about tanning."
Probably longer. Tanning parlors are still much in vogue in the U.S., and many owners boast that their lamps generate mainly long-wave ultraviolet-A rays rather than the shorter-wave UVB rays that are known to cause sunburn and basal- and squamous-cell carcinomas. But Dr. John DiGiovanna, a National Cancer Institute dermatologist, insists that UVA, which penetrates deeper into the skin than UVB, causes cancer. Its role, he says, "simply hasn't been as widely recognized as UVB's because its intensity in solar radiation is much less than UVB's." He asks, "Who knows what will happen in these tanning booths? People have never been exposed to such high doses of UVA before." Dr. Laurence David, a Hermosa Beach, Calif., dermatologist, is more vehement. "Tanning parlors are carcinogenic," he charges. "We've got to get this George Hamilton look out of our minds." That may be difficult. "Young people are continuing to use tanning parlors," says an East Coast dermatologist. "They are simply guaranteeing my future income."
Dermatologists are busy enough today, excising keratoses and skin tumors by surgery, freezing them, burning them out with an electric needle or bombarding them with radiation or laser beams. Once a skin tumor has metastasized, however, modern medicine is still largely stymied. When a malignant melanoma has reached that stage, for example, the victim's survival rate drops to below 10%. "The best way to treat skin cancer is to remove the tumors before they * spread," says Steven Rosenberg, chief of surgery at the National Cancer Institute. Conventional cancer treatments -- surgery, chemotherapy and radiation -- are largely ineffective against advanced melanoma, he says. But Rosenberg has had some success with a fourth, still unconventional treatment. He calls it "biological therapy," a strategy for spurring the body's immune system to attack and destroy the malignant cells.