by Rajeev Gupta, Community Pharmacist

Skin cancer is the most common form of cancer to affect Canadians. The incidence has more than doubled in the past 15 years. With the thinning of the ozone layer in recent years, more of the sun’s ultraviolet (UV) radiation is able to reach the earth’s surface. UVA and UVB are significant groups of radiation that can cause sunburns that may eventually increase the risk of skin cancer.

Factors that Increase the Risk for Skin Cancer:

• Overexposure and prolonged exposure to the sun’s UV rays. Damage caused to the skin is cumulative and depends on lifetime sun exposure.
• Use of tanning beds and sunlamps.
• Having several blistering sunburns during childhood or adolescence.
• People with light-coloured skin, eyes, and hair or a freckled complexion.
• Working outdoors (e.g., fishing, farming) or workplace exposure to x-rays, petroleum products, or arsenic may increase the risk of non-melanoma type skin cancers.
• Having many or atypical moles on the skin or a first-degree relative with a history of melanoma increases the risk for melanoma skin cancer.
• A history of immune system problems.

The outermost layer of the skin, the epidermis, is covered with squamous cells. The base of the epidermis has basal cells, which contain pigment-producing cells called melanocytes. The pigment, melanin, gives the skin a brown colour when tanning and is actually a sign that the skin has been damaged by the sun’s rays. When overexposed to UV rays, the skin cells may start to divide without control and eventually form a cancerous growth.

Three Main Types of Skin Cancer:

Malignant melanoma accounts for about 7 percent of all skin cancer and is more common among younger people. It originates from the malanocytes and can appear in areas not routinely exposed to the sun. Malignant melanoma can spread to other parts of the body, so it is the most deadly type of skin cancer.

Melanomas often appear as dark growths in the pigmented cells of moles, typically on the upper and lower extremities, trunk, or head and neck. To help identify melanomas at an early stage it is important to watch for new moles or changes to an existing one. The acronym ABCD is helpful in detecting characteristics of melanoma: Asymmetry–one half of the mole looks different from the other; Border irregularity–ragged edges, mottled appearance; Colour–new colour, may turn shades of black, brown, red or white; and Diameter–size enlarges slowly or quickly to a diameter greater than about 6mm.

Squamous cell skin cancer develops in the upper layer of the skin and accounts for about 20 percent of skin cancer. Some identifying features are:

• Appears as a red raised scaly bump that may bleed to become a crusted sore.
• Usually located on sun-exposed parts of the body such as the face, neck, rim of ears, hands.
• More common in middle age and elderly people.
• May be life-threatening since the lesions can grow in size and spread to other parts of the body.

Basal cell skin cancer develops in the basal (bottom layer) cells of the skin and accounts for about 75 percent of skin cancers. It is the most common form of skin cancer and is identified as:

• A slow-growing, flesh-coloured, red or black round growth that does not heal. It can develop into an ulcerating sore.
• Most often appears on the face, trunk, and upper back of fair-skinned sun-exposed people.
• Rarely spreads but can invade healthy tissue and cause disfigurement.

After a physical examination for the signs of skin cancer, a physician will usually do a skin biopsy to confirm the diagnosis. This involves removing a sample of cells or tissue from the growth and checking for the presence of cancerous cells. If skin cancer is detected, treatment is selected based on factors such as the type of cancer, size and extent of spread to other parts of the body (called “stage of cancer”), location, and growth patterns.

If detected and completely removed at an early stage, basal and squamous cell skin cancer can have cure rates exceeding 90 percent. Melanoma lesions that are at an early stage are usually surgically removed. However, if the melanoma has grown downwards into the skin and spread to organs such as the liver, lungs, and brain, chemotherapy and radiotherapy may be used as additional therapies.

Reducing the Risk of Skin Cancer:

The most effective method for reducing the risk of developing skin cancer is to limit exposure to UV radiation. Some recommendations include:

• Reduce sun exposure between 10:00 am and 4:00 pm, and try to stay in the shade.
• During outdoor activities, wear sunglasses with UV protection, wide-brimmed hats, and clothing to cover arms and legs.
• Apply sunscreen with UVA and UVB protection with a minimum SPF of 15. Try to apply sunscreen 15 to 30 minutes before going out, and reapply after swimming or sweating.
• Remember, reflected UV rays from surfaces such as sand, water, and snow are as dangerous as those received directly from the sun.
• Tanning parlours and sunlamps are also a source of harmful UV rays that increase the risk of skin cancer, so they should be avoided. No tan is a safe tan.

Regular self-examination of the skin can allow for early detection of skin cancer. A good time is after a bath, before dressing, in a brightly lit room. While in front of a full-length mirror and using a hand-held mirror, check the entire body (scalp, under breasts for women, genitalia, underarms, spaces between toes, and so on).

In particular, consult your physician if you notice:

• A mole or birthmark that appears to be changed in shape, size, or colour.
• A new growth on your skin.
• A sore that is not healing.
• A mole that bleeds or oozes.
• A mole that itches or becomes swollen or bumpy.

Skin cancer is the most common form of cancer to affect Canadians. It is also the most preventable. Community pharmacists are frontline health care professionals who may be able to help you understand and prevent skin cancer.

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