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Skin Cancer

Prevent and diagnose it early


Skin Cancer

Learn how to prevent skin cancer, and recognize the signs of melanoma, squamous cell carcinoma, and basal cell carcinoma.

The first Monday in May is “Melanoma Monday.” Most of us don’t think much about skin cancer, though it’s common. What seems like a harmless small growth has the potential to spread, and the effects can be devastating. Skin cancer is preventable, and unlike many cancers you may be able to recognize the first signs.

Risk factors

Before we discuss the most common types, here are some general risk factors that predispose people to skin cancer.


UV radiation in sunlight is the number one risk factor. The more lifetime sun exposure you have, the higher the risk.

Severe sunburns

If you have even one severe, blistering sunburn, it increases your risk. The most damaging sunburns happen in childhood, but adult burns are still risky. Even if your skin tans easily, tanning increases lifetime sun exposure and risk.

Tanning booths

Artificial UV radiation is very damaging, particularly to younger people. Tanning booths produce stronger radiation than sunlight, and if used before age 35 the risk of skin cancer may be increased up to 75 percent. The World Health Organization has classified tanning beds as carcinogenic to humans, and the Canadian Cancer Society recommends that no person under 18 should use indoor tanning equipment.

The provinces of Ontario, Quebec, BC, Manitoba, PEI, Nova Scotia, New Brunswick, and Newfoundland and Labrador have passed legislation restricting the use of tanning equipment by young people.

Being fair-skinned

If you have light skin that burns easily or freckles, you are more vulnerable to developing skin cancer. Fair skin has less melanin pigment, which protects against UV radiation. People with blue or green eyes, or red or blond hair, are also more at risk.

Exposure to radiation

If you have had radiation therapy for cancer, you have a greater likelihood of developing non-melanoma cancer in the area that was treated, even many years later.

The three most common types of skin cancer


Melanoma is a cancer of the melanocytes, the cells that give our skin its pigmentation. It can occur on any skin surface; in men it is often on the head or neck, or between the shoulders and hips, and in women it is often on the lower legs or between the shoulders and hips.

The darker your skin, the less likely you’ll get melanoma. When melanoma does occur in dark-skinned people, it shows up in more unusual places, such as under the toenails, on the palms, or the soles of the feet.

Melanoma is the most dangerous of all skin cancers and spreads aggressively. Once it has spread beyond the skin, the potential for a cure drops dramatically.

Melanomas often develop out of existing moles, and if you have more than 50 “common” moles on your body, you are at increased risk and should have a doctor check your skin annually.

The first sign of melanoma is often a change in the shape, size, colour, or texture of an existing mole. Please see the accompanying sidebar on the “ABCDE” approach to diagnosing melanoma.

Squamous cell carcinoma

This skin cancer is the most strongly linked to lifetime sun exposure and childhood overexposure. It can occur in both light- and dark-skinned people and most commonly is found in fair-skinned people in sun-exposed areas such as the head, face, ears, neck, and backs of hands. In dark-skinned people it is more likely to occur in areas less exposed to the sun such as the legs and feet.

As fair-skinned people age, they often develop flat, scaly brown or red patches on sun-exposed areas such as their face and backs of hands. These growths, called actinic keratoses, can develop into squamous cell skin cancers and need to be watched closely.

Signs of a squamous cell cancer include a new hard spot or lump on your skin, often with a rough, scaly, or crusty surface. It can also appear as a sore that won’t heal.

Basal cell carcinoma

Basal cell skin cancer is the most common skin cancer in fair-skinned people. It occurs primarily in sun-exposed areas, most commonly the face, but also on the scalp, ears, hands, shoulders, and the back. It is the least dangerous skin cancer, as it rarely spreads to other parts of the body and usually only causes local damage as it grows.

This cancer often appears like a shiny, smooth lump or nodule. It may crust, itch, bleed, and fail to heal.

Get to know your skin well so you will notice anything new. Do a regular skin self-exam of your entire body using a mirror. Whenever you see changes to an existing lesion or find a new one that’s acting differently or doesn’t heal, show it to your doctor.

The ABCDEs of melanoma warning signs

Letter Characteristic Change
A asymmetry the shape of one half of a mole no longer matches the other half
B border irregularity ragged or blurred edges; pigment spreading into surrounding skin
C colour is uneven new shades of black, brown, tan, or other colours
D diameter the size of the mole increases; some melanomas are very small but most are larger than the head of a pencil eraser
E evolving the mole has changed in weeks or months

Any time you have a mole that is changing, or a new mole that looks unusual or is growing quickly, show it to your medical doctor.

How to protect yourself from skin cancer

  • Avoid being outdoors during the middle of the day when the sun’s rays are strongest (10 am to 4 pm).
  • Remember that the sun’s rays are reflected by sand, water, snow, ice, and pavement, and can penetrate clouds and windows. Protect yourself with proper clothing and sunscreen.
  • Wear long pants and sleeves and clothes made from tightly woven fabrics when in the sun; UV rays can go through light clothing.
  • Wear a wide-brimmed hat that shades your face, neck, and ears; ball caps and visors only partially protect.
  • Use good quality broad spectrum sunscreens that filter UVA and UVB rays, with an SPF of at least 15, but 30 is recommended. Sunscreens with an SPF significantly above 30 don’t provide significantly more protection, despite claims. Apply to exposed skin 30 minutes before going out and reapply every two hours or sooner if you have been swimming or sweating.
  • Avoid chemicals in sunscreen such as oxybenzone, which is found in 80 percent of sunscreens. It penetrates the skin and can cause allergic reactions and hormonal disruption.

Choose a sunscreen that uses minerals to filter UV rays, such as zinc oxide and titanium oxide. Natural and organic sunscreens contain less harmful chemicals than conventional sunscreen products. For more information on how to choose a safe sunscreen, and a detailed analysis of many popular brands, check out the Environmental Working Group’s annual guide to sunscreens at



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