When Andrea Lancaster moved to Sarasota four years ago from Providence, R.I., a rash of red swatches erupted on her legs. Two years later, the rash had spread so far that she was embarrassed to be seen in shorts, she made an appointment with a dermatologist.

Dr. Anne McBride of Intercoastal Medical Group examined the patches, pronounced them harmless, then glanced at a small mole on her back and asked, "How long have you had this?"

Lancaster answered that it had been a few years. "It was always in the back of my mind," she says now, but she'd paid it little attention until she heard the concern in her doctor's voice.

"I don't want to scare you," she recalls McBride saying, "but we've got to get this looked at." Within minutes, the doctor had sliced off the suspicious mole, and a week later, Lancaster got the news: malignant melanoma. To this day, the slim, 34-year-old media coordinator isn't sure whether she heard it in the doctor's office or on the telephone. "I can remember her saying it," she says. "I just can't tell you when or where."

A battery of chest X-rays and blood tests followed; amazingly, the cancer hadn't spread to her lungs or lymph nodes. Lancaster was immediately referred to a plastic surgeon, who carved out the cancer under local anesthesia while she lay awake on her stomach. "It was a small mole," Lancaster emphasizes. "That's why I didn't worry about it."

But that misconception could have cost Lancaster her life. "People think that melanomas are big, lumpy, bleeding masses. Often they're just a flat, freckle-shaped thing. More than half the people I diagnose don't even know they have one."

Melanoma is a deadly form of skin cancer that the National Cancer Institute says will strike nearly 54,000 Americans this year and kill some 8,000. In men, it occurs more frequently in the area between the shoulders and hips, the head and neck. Women see it more often on the lower legs.

And here's an eye opener: Sarasota dermatologist Dr. David Sax says that if you were alive in 1935, your chance of developing melanoma was one out of 1,000. By the year 2000, that number jumped to one in 75. He says the American Cancer Society predicts that by 2010, it will be one in 50. "Is it because we're picking it up quicker?" asks Sax. "Or is it because we're simply spending more time in the sun?"

The truth is, no one's sure. "It's not as straightforward as you think," says McBride. "There's a lot of debate about whether one is predisposed to melanoma versus whether it's caused only by sun exposure."

Risk factors include having more than 50 moles and being fair-skinned with blue eyes. Melanoma is rare in dark-skinned races (it generally occurs under their nails or on the palms or soles of their feet). There is sketchy evidence that a previous history of more common skin cancers like basal or squamous cell carcinoma may increases your risk, and melanoma rates are higher in areas that experience year-round ultraviolet radiation from sunlight.

There may also be a genetic link; about 10 percent of all melanoma patients have a family history. Two of Lancaster's brothers have had pre-cancerous lesions, and one grandmother was diagnosed with melanoma on her neck several years ago.

Lancaster hardly fits the physical prototype. Half-Italian and half-Irish with dark hair and deep brown eyes, she seldom went to tanning beds, but as a teen-ager in Massachusetts she lived for the scarce weekends of sun and remembers numerous hard burns on her back. "Now I think back on those days and cringe." (Another risk factor is having at least one blistering sunburn during childhood.)

"Statistically, [Lancaster] is at a higher risk for another melanoma," says McBride, a fair, red-headed woman who had a basal cell carcinoma removed herself when she was only 28. "I've seen many patients develop two or more melanomas. But once you get it, you can still go out into the sun. If you're using sunscreen properly, I'd rather people go ahead and remain physically active."

Still, Lancaster hasn't been to the beach in a bathing suit since her diagnosis two years ago, and she uses sunscreen on her face every day, regardless of where she'll be. "I won't even allow my back to go into the sun," she says.

McBride acknowledges that she sees more melanoma cases here than in her previous practice in Pittsburgh. "One of the advantages to living in Florida is that because of our older demographics, dermatologists and general practitioners are more attuned to looking for it."

But she and Sax both know that no one can tell for sure just by looking at a mole whether it's cancerous. The only way to make a definite diagnosis is to have a pathologist examine the mole and surrounding tissue. Depending on the extent of the cancer, treatment can range from surgery to radiation and chemotherapy. If a large area of tissue must be removed, a plastic surgeon may be called in to perform a skin graft.

"The cure rate is nearly 100 percent if caught early," says Sax. If not, it can spread to other organs, like the liver, lung or brain. When it spreads, it is called metastatic melanoma, and there is significantly less hope for cure.

Lancaster was lucky. "My doctor told me that if I'd waited six more months, it would have been fatal," she remembers. "As soon as I start to think about, 'What if?' I go blank. My mind just won't go there."

Her bout with the disease has left her with a three-inch scar above her right hip and a lifetime of annual chest X-rays. She sees her dermatologist every six months for a head-to-toe examination must also see an ophthalmologist on a regular basis, because her skin cancer puts her at raised risk for melanoma of the eye.

"With melanoma, you're never released," says McBride. This distinguishes it from other cancers, which are considered cured after five years. "It can and does come back, sometimes many years later."

Prevention includes regular dermatological visits, protective clothing and being vigilant about sunscreens; although Sax cautions that lotions can't provide total protection. "I'm not a big fan of people sitting on the beach all day just because they wear sunscreen. A sunscreen is just that, a screen," says Sax. "They're tested for efficacy at twice the concentration used by the average sunbather. So unless you're slathering on an SPF 15, you're really only getting an effective protection of a 7 or 8."

Sax says the average patient with no history or significant number of moles should see a dermatologist for a thorough full-body examination by the mid-20s. Until then, parents should be alert to moles on their children that change out of proportion to their age. Says Sax, "I've taken melanomas off 16- and 17-year-olds."

It frustrates McBride that schools in Florida have no programs that emphasize the dangers of the disease: "I don't see people changing their behavior. It's still too typical that teenagers get a lot of sun exposure."

It bothers Lancaster, too, whenever she goes to visit her nieces up in Massachusetts. "At first they were terribly concerned about me," she says. "But just this Christmas, they said, 'See you later, we're going to the tanning salon.' I couldn't believe it. Didn't anything that happened to me register with them at all?"

REMEMBER YOUR ABC'S-AND D'S

"Not every change in a mole is sinister," says Sarasota dermatologist Dr. David Sax. "Moles can change by themselves, and they often regress with age." But be alert to any mole that develops scales, begins to itch, or becomes hard and leathery. Here are the other warning signs.

Asymmetry: irregular shape.

Border: ragged, notched or blurred outlines.

Color: uneven shades of black, brown, tan, white, gray, red, pink or blue.

Diameter: change in size to larger than 1/4 inch.

If there's a family history of melanoma, Sax advises genetic testing to determine if you're at higher risk.

THERE GOES THE SUN

Doctors and skin care specialists all agree that the most important way to prevent skin cancer is to protect yourself from the sun. "A tan is an antiquated ideal of beauty," says Tara Raven, a licensed aesthetician with le Parasol Skin Care (351-6131). In addition to her favorite lotion, Skinceuticals Sunscreen in 20 SPF, she recommends daily use of topical vitamin C for the face, hands and arms. "It helps the skin to produce collagen and elastin," she says, and that can help maintain skin cells' normal function.

At Capriccio (924-5969), manager Rita Niro carries Pevonia Botanica moisturizers with sunscreens that are formulated especially for the face; they include variations for dry, oily and sensitive skin.

And clients at Neoderm (951-0388) can choose from more than a dozen sunscreens that range in SPF from 15 to 65. Clinical aesthetician Sandra Day advises people to tailor their sun protection to their lifestyle. "What you'd wear to go to work everyday is not what you'd wear to go boating," she says. Her personal favorite is Z-Silc, an emollient that contains micronized zinc oxide to combat both UVB and UVA rays, but her most popular product is Ti-Silc. Not only does it deliver a powerhouse 45 SPF, it's also flesh-tinted and contains an antioxidant.

TO REDUCE YOUR RISK

Avoid exposure to the sun from 10 a.m. to 4 p.m., or at least wear long sleeves, pants and a wide-brimmed hat. Solumbra carries a line of SPF30-rated protective, lightweight clothing that is medically recommended. You can view their products at www.solumbra.com.

Invest in sun-protective coatings for car and home windows.

Wear a sunscreen of SPF 30 or higher.

Wear sunglasses with lenses that have UV-absorbing lenses that block at least 99 percent of UVA and UVB rays. (Melanoma also affects the eyes.)

INSPECT YOURSELF

According to the National Cancer Institute, the best time to check your skin is after a shower or bath, in a well-lit room with a full-length and a hand-held mirror. Here's what to look for:

Any new mole that looks abnormal.

Any change in the size, shape, color or texture of an existing mole.

Any sore that doesn't heal.

Check every inch of your body, including the genital area and scalp (don't be squeamish here-your life could depend on it). Start with the front and back of your body, then each side. Move on to your fingernails, palms, forearms and upper arms. Finally, check the soles of your feet, the spaces between your toes and your toenails.

Sarasota dermatologist David Sax often refers patients to a professional medical photographer who will photograph their body, then store the images in a software program that can be used to map any changes to moles.