How to avoid getting skin cancer

Originally published in The Ottawa Citizen May 7, 2002
Original Title: Irradiate My Soul and Thanks for the Tan

With the summer months approaching, the ozone hole growing and the tan enthusiasts ready to hit the beach, it is important to know how skin valiantly tries to protect itself. Alas, people subject their dermis (skin) to multitudes of insults and injuries. Cuts, bruises, scrapes and mild burns heal well and cause no lasting damage. Ultraviolet radiation (UV) is less forgiving.

Skin will tan to create a protective shield in response to UV exposure. The darker the tan, the less UV will be able to penetrate through the skin. There are three UV wavelengths, UVA I, UVA II and UVB. The latter two wavelengths are the major cause of sunburn. UVB is more damaging to skin because of its deeper skin penetration. UV damages or mutates the skin’s DNA, causes pigment changes, wrinkling and loss of skin elasticity. Skin pigment cells (melanocytes) can mutate and become cancerous.

Even though the tan may fade over the winter, the UV effect upon the skin is permanent. The damage is cumulative. Repeat sunburns and regular exposure to tanning beds among other factors continues the cycle of DNA damage. Skin will prematurely age becoming leathery and lose its suppleness.

The most serious skin cancer is malignant melanoma. It accounts for 75% of all deaths due to skin cancer. It is responsible for one to two percent of all cancer deaths in North America. In 1960, the lifetime risk of developing melanoma was one in 1500. By 2000, the risk stood at one in 70. The incidence of melanoma has doubled in the past decade mostly in people between 20 to 45 years of age. It ranks seventh in cancer incidence for females and sixth for males. Death rates are increasing by two percent per year. Survival rate are improving as well.

The greatest risk factors for melanoma are a history of a changing mole, a family history of melanoma and a personal history of having melanoma.

Since 80% of lifetime sun exposure occurs before age 18, a person’s skin type plays a role in their skin cancer risk. People with very dark or black skin rarely experience sunburn. There are four sun-reactive skin types for people with white skin.

People with Type I skin never tan and always sunburn. Those with Type II tan less than average, have difficulty tanning and usually burn. Both types tend to be found in people with pale skin, red or blond hair, blue eyes, freckles and who are of Celtic ancestry. Some people with dark brown hair and blue/green eyes are included in this category. The majority of people have Type III skin. Their skin tans about average and only sometimes does it mildly burn. Indeed, this group also is most likely to have a history of deliberately prolonged or repeated sun exposure in order to obtain a cosmetic tan.

Type IV skin rarely burns and is generally seen in people with dark swarthy skin. It easily tans and is the least likely to become cancerous.

Early detection and consistent use of sunscreens is the best means of preventing skin cancer. If you are concerned about the appearance of a mole on your skin the following ‘ABCDE’ criteria for melanoma risk may be helpful:

  • Asymmetry: If the mole is divided in half by an imaginary line, both halves should appear identical for a non-cancerous (benign) mole.
    Borders: The benign mole is usually round having sharp well-defined margins. A ragged or uneven border is not normal.
  • Colour: A mole having a homogenous brown colour is normal. Multishaded moles or those that have a combination of colours such as blue, purple, red or black are suspicious for cancerous change.
  • Diameter: Moles greater than 6 millimetres (~3/8 inch) in diameter, about the size of a pencil eraser, are suggestive of melanoma.
  • Enlargement: A recent increase in the size of the mole warrants further investigation.

Any abnormal finding should be seen by your doctor. Some of the signs of non-melanoma skin cancers include: Red, flaky, itchy irritated patches, ulcers that do not heal in two weeks, areas of skin that keep cracking and bleeding or become rough, red and bumpy. Check your skin at six-month intervals. Skin cancers grow slowly. Many people in Canada have a childhood history of many sunburns while swimming or doing outside sports or chores. They particularly need to be careful about further exposure.

Sunblock, protective clothing, caps, hats and UV-blocking sunglasses are the mainstays of prevention. Choose a UVA and B sunblock that has a sun-protection-factor (SPF) of at least 15. Using sunblock can lead people to get more exposure because of a false sense of protection. The best protection is to not spend too much time outdoors when the summertime sun is highest and hottest (between 10 AM and 4 PM). Using an awning for a children’s play area or an area where you sit outside and read adds an additional layer of protection to your hat and clothing. UV comes through the clouds so a cloudy day offers little protection.

Reduce your exposure to pesticides and herbicides containing organic arsenic. These compounds increase the risk of skin cancer. Tanning booths, claims to the contrary, irradiate the body with skin-damaging UV to stimulate the tanning process.

The goal is to avoid UV radiation exposure and sunburn. No one wants skin that looks better on alligators or Komodo Dragons.

© Dr. Barry Dworkin 2002

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