TORONTO -- It could appear on your scalp. Or the sole of your foot. Under a fingernail. Or on a stretch of your back that is virtually impossible to see without a three-way mirror.

Skin cancers can show up anywhere. And while we all should be keeping an eye out for moles on our skin that are changing colour or size, there are a lot of other people who can help detect skin cancer as well.

Your hairdresser or barber sees far more of your scalp than you ever will. A massage therapist gets a great view of a client's back. A podiatrist can see the undersides of feet or the cracks between toes.

Any person who provides a health-related service -- they are often called allied medical professionals -- or even a beauty-based one can play a role in early detection of skin cancer, suggests Dr. Richard Langley, president-elect of the Canadian Dermatology Association.

"Skin cancer can occur on any cutaneous surface ... from the feet up to the scalp. So when you think about it, you can see that there is a broad group of medical, allied medical and non-medical (professionals) that could provide a benefit to patients by screening in these areas," says Langley, who is a professor of dermatology and director of dermatology research at Dalhousie University in Halifax.

"So hairdressers. Chiropractors. Massage therapists. Respiratory therapists. Estheticians. Podiatrists. Orthotics (fitters). All of these groups are examining the skin and are able to see and identify a lesion that may be of concern."

Some already consider informal skin cancer screening as part of their job.

Melanie Dowell, a registered massage therapist from Tantallon, near Halifax, remembers spotting a lesion she didn't like the look of on the back of a new client a few years ago. It was dark, with jagged edges.

"The red flag went up for me," says Dowell, whose training program at Northumberland College in Halifax included a section on differentiating cancerous from non-cancerous moles and lesions.

She asked the woman about it. The client said she'd had the mole examined by her doctor and he'd assured her it was fine. But when the woman came back for a second massage, Dowell urged her to go back and get the mole rechecked.

The woman didn't book a third appointment. "I figured I probably annoyed her or something and she went off somewhere else," Dowell says.

Months later, she got a thank-you letter from the woman, who had followed Dowell's advice. The mole was diagnosed as melanoma, the most dangerous type of skin cancer. The letter said the surgeon who removed the lesion told the woman she was lucky she had sought care when she did.

The letter came with a small present. "She gave me an angel ornament and said I was her angel and I saved her life," Dowell says.

Danielle Love, a registered massage therapist from Halifax, makes a point of scanning her clients' skin. She is also a graduate of the Northumberland College program. If she sees something she thinks bears looking into, she'll suggest clients see their doctor.

Several years ago she noticed something different on one of her long-time clients and made the recommendation. The client's doctor dismissed the concern, but the woman persisted and got a referral to a dermatologist. In this case, too, the lesion was cancerous.

"They got it in time. And she was so thankful," Love says.

There are three major types of skin cancer: basal cell carcinoma, squamous cell cancer and melanoma. Basal cell cancers are the most common; they rarely spread. Squamous cell cancers can occasionally spread to other parts of the body.

Melanoma is the least common of the three types of skin cancer and is the most dangerous. While curable if found early, its prognosis is poor if found later in the disease.

The Canadian Cancer Society estimates that this year, 5,800 Canadians will be diagnosed with melanoma, and 970 will die from the disease.

According to the Canadian Dermatology Association, one in 74 Canadian men will develop melanoma in their lifetime; for women, the rate is one in 90.

Langley says skin cancer lends itself well to being spotted at home or in the offices of massage therapists, podiatrists or the like.

Where internal cancers may require scans or sophisticated tests to diagnose, anyone who makes a point of learning what skin cancer looks like can play a role in detecting it.

Dermatologists have developed a useful mnemonic to remind people what to look for when they are assessing a mole as a possible melanoma. They say you should remember your ABCDEs.

These moles can be asymmetrical (A), have an irregular border (B), have different colours (C) within the one mole, can increase in diameter (D) and evolve (E) in shape, colour, size or symptoms. In terms of symptoms, they can itch, be tender to the touch or bleed.

"What we know from research is that over 50 per cent of the most serious form of skin cancer, melanoma, has been recognized by patients," he says.

"With the Internet and a more educated population, I have had patients come in and say that they're concerned that a lesion on their back may be a melanoma. And in fact they've been right."

Langley has also had indirect referrals from hairdressers and massage therapists, and welcomes their help.

"We actually rely and we encourage people to become educated to do that," he says.

"There's no question that anyone out there who has an interest can make a diagnosis of skin cancer or at least recognize that there is a lesion that needs to be assessed."