The Canadian Cancer Society estimates there will be an estimated 5,000 new melanoma cases and 940 melanoma-related deaths in Canada in 2009. (Krista Niles/Associated Press)Melanoma is the most dangerous type of skin cancer. It often starts out as a coloured mole or spot, but can spread fast to surrounding skin and other organs. Melanomas make up only one or two per cent of all skin cancers, but they are the type most likely to be fatal.

The skin's melanocytes (cells that determine skin colour) produce a pigment called melanin that gives skin its colour and protects it from sun damage. When skin is exposed to the sun, it produces more pigment and darkens. Melanocytes often cluster together and form moles. Most moles are benign, but some become malignant melanomas.

Are there different forms of the disease?

There are four types of melanomas, depending on their location, shape, and whether they grow outward or downward into the skin.

• Superficial, spreading or flat: Grows outwards at first and forms an irregular pattern on the skin, with an uneven colour.
• Nodular: Is lumpy and often a blue-black colour. It may grow faster and spread downwards, into the skin.
• Acral melanomas: Develop on the palms of the hand, soles of the feet or the nailbeds.
• Lentigo maligna: Usually develops on the faces of elderly people.

What causes melanomas?

The biggest contributing factor is the skin's sensitivity to ultraviolet (UV) rays. Melanoma cancer typically starts in areas exposed only occasionally to the sun, such as the back, and the backs of the legs.

Who's at risk?

People who have:

• Lots of moles, particularly atypical moles (irregular shaped, but benign).
• Family history of melanoma in more than one relative.
• Blond or red hair.
• Fair or freckled complexion.
• Had a severe sunburn during childhood.

As well, incidence rates and mortality rates appear to be higher for men.

Are rates rising?

Yes, says Dr. Gang Li, associate professor of dermatology and skin science at the University of British Columbia.

"It's increased quite dramatically in the past few decades," says Li. He says it's unclear why, but he has a couple of theories.

"One thing could be the thinning of the ozone layer, which provides a filter for the UV light," he says. "If the ozone becomes thin, there is more UV light. Another thing is a lot of people like going to the beach and getting a suntan."

Melanoma incidence rates are increasing for both men and women. But the death rates are increasing for men and dropping for women. Li says it is unknown what's behind this pattern.

There will be an estimated 5,000 new melanoma cases and 940 melanoma-related deaths in Canada this year, according to the Canadian Cancer Society.

What's the treatment?

The Canadian Cancer Society recommends reducing sun exposure between 11 a.m. and 4 p.m. and using sunscreen with an SPF 15. (Mary Godleski/Associated Press)Treatment depends on how thick a melanoma is. It could be surgery, biological therapy, chemotherapy or radiation therapy.

One option is to surgically remove part or all of the tumour and the surrounding tissue. If the tumour is large, a skin graft may be needed as well.

However, the decision to have surgery depends on where the tumour is and how close it is to vital organs.

Another treatment is biological therapy. This involves administering special proteins or substances (similar to vaccines) to fight cancer cells or help boost the body's immune system.

Chemotherapy involves using drugs or medications to interfere with the cancer's ability to grow and spread. However, the drugs affect healthy cells too, leading to nausea, vomiting, loss of appetite, fatigue and hair loss. But these symptoms can be controlled. This treatment is rarely used for melanoma, but can be helpful in some cases.

Radiation therapy, which is also rarely used, involves using high energy X-rays to destroy cancer cells. The treatment can damage tissues near the tumour, but this can usually be controlled.

Are you likely to survive if it's caught early?

Yes. About 90 per cent of melanoma can be cured if caught in the early stages.

To catch it, here are some telltale signs to look for:

• Any birthmark or mole that changes in its shape, colour, size or surface.
• Any new growth on your skin — pale, pearly nodules that may grow larger and crusty, or red, scaly, sharply defined patches.
• Any sore that doesn't heal.
• Any patch of skin that bleeds, oozes, swells, itches or becomes red and bumpy.

Does it spread rapidly?

Yes. It spreads faster than the other types of skin cancers. It varies from case to case, but it could spread from the skin to the lungs and other organs within months, says Li.

Can I get it if I use a tanning bed?

Yes. Exposure to UV rays can lead to melanoma, but Li says rays from a tanning bed can be especially harmful. There are three different types of UV rays: A, B and C. UV A — the kind found in a tanning bed — is the most carcinogenic.

How can I reduce the risk of developing melanomas?

The Canadian Cancer Society and the Canadian Dermatology Association recommend that Canadians:

• Reduce sun exposure between 11 a.m. and 4 p.m.
• Stay in the shade whenever possible.
• Put on clothing to cover your arms and legs.
• Wear a wide-brimmed hat.
• Use sunscreen (SPF 15 or higher).
• Keep babies younger than one year out of the direct sun.
• Avoid tanning parlours and sunlamps.