Skin cancer

The skin is the largest organ in your body, and it protects you from things like dehydration (too little water in your body), the sun, bacterial infections, and pollution.

But there are limits to your skin's ability to protect you. Ultraviolet (UV) radiation -- also known as UV rays -- damages the DNA of your skin cells, which can cause skin cancer.

Most cases of skin cancer are preventable. You can reduce your risk of getting skin cancer by following these safety tips:

• Cover up. When the UV Index is 3 or higher, protect your skin as much as possible. Wear light-coloured, long-sleeved shirts, pants, and a wide-brimmed hat made from breathable fabric. When you buy sunglasses, make sure they provide protection against both UVA and UVB rays.
• Limit your time in the sun. Keep out of the sun and heat between 11 a.m. and 3 p.m. The UV index in Canada can be 3 or higher during those times. When your shadow is shorter than you, the sun is very strong. Look for places with lots of shade, like a park with big trees, partial roofs, awnings, umbrellas or gazebo tents. Always take an umbrella to the beach.
• Use the UV Index forecast. Tune in to local radio and TV stations or check online for the UV index forecast in your area. When the UV index is 3 or higher, wear protective clothing, sunglasses, and sunscreen, even when it’s cloudy.
• Use sunscreen. Put sunscreen on when the UV index is 3 or higher. Use sunscreen labelled “broad spectrum” and “water resistant” with an SPF of at least 30.
• Drink plenty of cool liquids (especially water) before you feel thirsty. If sunny days are also hot and humid, stay cool and hydrated to avoid heat illness. Dehydration (not having enough fluids in your body) is dangerous, and thirst is not a good indicator of dehydration.
• Avoid using tanning equipment. There is no such thing as a ‘healthy’ tan.  Using tanning equipment damages your skin and increases your risk of developing melanoma, the deadliest form of skin cancer.

Ask your doctor, nurse or pharmacist if any of the medications you are taking could be harmful to you if you are exposed to UV rays. The best way to find skin cancer in its early stages is to examine your skin often. See your doctor right away if you notice any of the following:

• abnormally dark or discoloured patches or spots
• bleeding, crusting or change in the colour, size or shape of a mole

Types of skin cancer

There are three main types of skin cancer:

• basal cell carcinoma
• squamous cell carcinoma
• malignant melanoma.

Most cases of skin cancer in Canada are either basal or squamous cell carcinomas. These skin cancers tend to develop later in life on areas of skin that have been exposed many times to the sun (like the face, neck or hands). Basal and squamous cell carcinomas progress slowly and rarely cause death because they usually do not spread to other parts of the body. These cancers are usually easily removed by surgery. But they are still a concern because they can cause scarring, disfigurement, or loss of function in certain parts of the body.

Malignant melanomas are different. They account for about 5% of all skin cancers, and are the type most likely to be fatal. Unlike other skin cancers, they happen earlier in life and progress rapidly. They may develop on almost any part of the body.

Melanoma is especially hard to stop once it has spread (metastasized) to other parts of the body. But it can be readily treated in its earliest stages. The main factors that predispose an individual to the development of melanoma seem to be recreational exposure to the sun and a history of sunburn.

Causes of skin cancer

One of the main causes of skin cancer is being exposed to UV rays. UV rays are invisible, and are produced by the sun, and tanning equipment.

UV rays cause skin cancer by creating changes in the cells of your skin. In some cases, the UV rays cause direct damage to your cells. Tans and sunburns, for example, are both signs that UV rays have damaged your skin. In other cases, UV rays cause skin cancer indirectly, by weakening the immune system.

Many studies on skin cancer show that people who have suffered many severe sunburns in childhood are at greater risk of developing skin cancer. Family history, some chemical exposures, and immune dysfunction conditions can also create a greater risk of developing skin cancer.

Detection and treatment

Moles, spots, and growths on your skin are usually harmless - but not always. That is why it is important to look at the skin all over your body once a month and have a doctor check you over once a year.

Using a bright light and mirrors, work from top to bottom, and examine your:

• head and face (use a blow-dryer to inspect your scalp)
• hands and nails
• elbows, arms, and underarms
• neck, chest, and torso (trunk)
• genitals and breasts
• back of neck, shoulders, upper arms, back, buttocks, and legs
• feet (including soles, heels, and nails)

Look for these "ABCDE" warning signs:

• Asymmetry. Do the two halves not match if you imagine drawing a line through the mole?
• Borders. Are the edges uneven, scalloped or notched?
• Colours. Are there many shades (brown, red, white, blue or black)?
• Diameter greater than 6mm. Is the mole the size of a pencil eraser or larger?
• Evolution. Has there been a change in size, shape, color, or height? Has a new symptom developed (like bleeding, itching or crusting)?

If you find any of these warning signs, see your health care provider as soon as possible. It is particularly important for you to choose a doctor who specializes in skin cancer and is trained to recognize a melanoma at its earliest stage.

If skin cancer is suspected, your doctor will take a biopsy (sample of tissue) and examine it with a microscope. If skin cancer is confirmed, there are many treatment options. The choice of treatment is based on the type, size, location and depth of the tumor, as well as your age and general state of health.

How the Government of Canada protects you

The Public Health Agency of Canada (PHAC) monitors cancer in Canada. PHAC identifies trends and risk factors for cancer, develops programs to reduce cancer risks, and researches to evaluate risks from the environment and human behaviours. Health Canada also promotes public awareness about sun safety and the harmful effects of UV rays.