Skin Cancer

Weighing in at about 3 kilograms, our skin is the largest organ in the human body. It protects the body against the environment, against dehydration, the sun, bacteria, pollution. Like our other organs, the skin can be damaged by stress. For skin, one of the primary stresses comes from ultraviolet (UV) radiation from the sun, which can cause skin cancer.

Skin cancer rates

This year about 76,000 Canadians are expected to develop skin cancer, which is 30 percent more than 10 years ago. Furthermore, according to some estimates, 40 to 50 percent of Americans who live to age 65 will develop skin cancer at least once in their life. Disturbing facts, yes, but fortunately skin cancer is largely preventable and usually curable. Early detection is the key.

People at risk

Some people are more at risk of developing skin cancer than others. Risk factors for skin cancer include:

  • having fair skin, fair hair, and blue, gray, or green eyes
  • spending a lot of time outdoors
  • having had previous sunburns, especially before the age of 18
  • having skin with numerous moles or atypical moles
  • having a close relative with skin cancer

Of course, you cannot change certain risk factors linked to heredity, such as your skin type. However, you do have control over how much you expose yourself to the sun.


Evidence now suggests that UV radiation can damage the DNA of a normal cell, even when the cell is exposed for only a short time. When the DNA is damaged, the cell tries to repair itself. If it can’t, it may become dysfunctional. There is typically a 10 to 30 year lag time between the excessive damage by UV radiation and the clinical appearance of skin cancer.


The skin spots, lesions, or tumours that appear in skin cancer come in a variety of forms, some of which are listed here:

  • A slow growing pearly nodule or round pink lump, possibly surrounded by blood vessels, with an ulceration in its center and pigmentation.
  • A flat or slightly depressed lesion that is hard to the touch, possibly yellowish with poorly defined margins.
  • Slow growing reddish, scaling plaque that may resemble dermatitis or psoriasis; it may be itchy and slow to heal.

Report any suspicious looking lesions to your doctor, especially if you are one of those at risk. Be wary of any spot on your skin – typically (but not necessarily) on the face, head, and neck – that changes size, shape, or colour over a period of 1 month to 2 years.


Do a total body check using a full-length mirror and a hand mirror once a month.

A mole, or nevus, is a small brown, more or less raised spot, resulting from the localized accumulation of pigment cells (melanocytes). Moles may be congenital or may appear any time after birth. They vary in appearance and size, ranging from a few millimeters to an inch or more (several centimeters) in diameter, but they do not change over time. A change in the appearance of a mole, especially congenital and large ones, may be a sign of its transformation into a melanoma. In this case, medical attention should be sought immediately.

Examine all spots or patches with a critical eye using what is now commonly referred to as the ABCDs of skin cancer:

  • “A” is for Asymmetry – one half of a mole that is unlike the other half.
  • “B” is for Border – the border or edges of the mole are irregular, scalloped, or poorly blurred.
  • “C” is for Colour – the spot varies from one area to another, displaying differing shades of brown, or black, sometimes with patches of white, red, or blue.
  • “D” is for Diameter – the spot is larger than 6mm as a rule (the diameter of a pencil eraser) or is growing.

Many doctors recommend that people at risk should have their skin examined every 3 years between the age of 20 and 40 and every year after age 40.


Stay away from tanning machines; there is no such thing as a healthy tan. Reduce exposure to the sun when its rays are strongest: between 10 a.m. and 4 p.m. Ultraviolet rays can penetrate clouds and cause sunburn or damage even on cloudy days. When outdoors, remain in the shade as much as possible, and watch for reflecting surfaces like sand, water or snow.

  • Slip on a shirt…over your skin to protect it from the sun; wear loose-fitting, tightly woven, lightweight clothing.
  • Slop on sunscreen…with SPF (sun protection factor) 15 or higher – that provide good protection against UVA too. Apply it 15 to 20 minutes before you go outside and reapply often, especially after swimming or exercise; protecting skin with sunscreen, especially during childhood, can decrease the risk of non melanoma cancer by 78 percent.
  • Slap on a hat…with a wide brim that covers your head, face, ears, and neck.

In February 2004, Canada adopted World Health Organisation’s updated UV Index for the public forecasting program. Watch for it to help you protect yourself appropriately. Keep in mind that the higher the UV Index number the stronger the sun’s rays, and the greater the need to take precautions. And remember: Eighty percent of your life exposure to sun occurs during the frequent but short trips outside to go to work or run errands.

Types of skin cancer

Basal cell carcinoma does not produce metastases, but it can cause ulcers.

Basal cell carcinoma does not produce metastases, but it can cause ulcers.

Basal Cell Carcinoma (BCC): This is the most common cancer and most common skin cancer, accounting for more than 75 percent of all skin cancers. It grows from the bottom (basal) layer of the epidermis (the outer layer of the skin) and almost always appears on sun-exposed skin, such as the forehead, hands, lips, or tops of the earlobes. Basal cell carcinoma does not produce metastases, but it can cause ulcers. Traditionally associated with older people, basal cell carcinoma is now seen in more young adults than in the past.

Squamous cell carcinoma: This cancer grows from the top layers of skin, and also results from excessive sun exposure as well as pipe and cigar smoking and some petroleum products. It can occur anywhere on the body as small, usually painless (but sometimes bleeding), skin ulcer or irregularity. It is common around the mouth and on the lip. It is sometimes preceded by a precancerous condition known as actinic keratosis, which appears as rough, brown, or red scaly patches.

Melanomas may be raised and rough to varying degrees.

Melanomas may be raised and rough to varying degrees.

Malignant melanoma is the deadliest form of skin cancer, but is also the least common. As with basal cell and squamous cell cancers, it is usually caused by excessive sun exposure. It runs in families and often arises in a pre-existing mole. Having a fair or freckled complexion naturally increase the risk even further.


Your doctor can usually tell by looking at a suspected lump or spot whether skin cancer is a possibility and will take a skin sample if there is any doubt.

Always practice safe sun precautions.

For more information or for support

Canadian Cancer Society