Preventing Skin Cancer

What you can do to prevent it

Annually, personnel at most Australian ADF airfields enjoy a considerable number of sunny days, particularly in the summer months. However, during this time, aircraft crewmembers and ground support staff are at risk of developing skin cancer as a result of time spent on airfield line areas and while outdoors during layovers (outdoor recreational activity, etc.), both of which can expose personnel to excessive amounts of ultraviolet (UV) rays.

The major cause of skin cancer is excessive exposure to UV light rays. Sunlight is the major day-to-day source of UV light, and a certain amount is beneficial. (The body produces vitamin D in response to exposure to sunlight.) But overexposure to sunlight, and particularly a severe sunburn, can significantly increase skin cancer risk. Excessive exposure in suntanning parlors should be avoided.

The extent of exposure to UV rays in sunlight is influenced by elevation, latitude, and cloud cover. UV-ray penetration is greater at higher elevations because the thinner atmosphere offers less filtering. The sun's rays are stronger and more direct closer to the equator. Crews flying to destinations with a combination of tropical or desert climate and high altitude should be especially cautious. Cloud cover blocks some UV rays, however, and areas with frequent cloud cover may have a UV-ray level that's 50 percent lower than areas that are generally sunny.

The portion of the electromagnetic energy light spectrum that is visible to humans is between the wavelengths of 380 nanometers (nm) to 760 nm (a nanometer is 1 millionth of a millimeter). At the end of the low-frequency portion of the light spectrum is the UV range (400 nm to 180 nm). The human retina does not detect light rays in this range, and it is defined, therefore, as invisible light. Nevertheless, UV rays are absorbed by human tissues and produce damage to cell genetic structures.

The beginning of the UV spectrum is arbitrarily divided into the UVA range (320 nm to 400 nm) and the UVB range (290 nm to 320 nm), with subsequent wavelengths becoming shorter and shorter. At the extreme low ends of the electromagnetic spectrum are X-rays, which are so short that some of them can pass through human-body tissues without being absorbed.

Skin cancer should not be feared excessively, but symptoms of a developing skin cancer must not be disregarded. Any unusual skin change, especially on the face, neck, shoulders, and arms, should be examined by a medical officer.

The growth of cancer cells in the body leads to the death of normal tissue. Each cell of the body contains a genetic code that tells the cell when to divide and when not to divide. A cancer cell is a formerly normal cell that has lost its genetic code. The marauding cancer cells produce their own death when they bring down the host within whom the cells originated. All types of skin cancer are serious, but the least serious (though not to be ignored) is basal-cell carcinoma, the most common of all types of cancers. The next most serious type of skin cancer is squamous-cell carcinoma, and the most deadly is the type known as melanoma, or malignant melanoma.

No one knows exactly how many skin cancers occur each year. In the United States, the American Academy of Dermatology (AAD) estimates that about 750,000 persons will develop basal-cell carcinoma. Few of these will die of the cancer because of its very slow growth rate and often successful treatment. The AAD estimates that squamous-cell skin cancers claim about 2,300 lives each year and that 6,800 lives are claimed by melanoma.

RISK HIGHER THAN EVER

The risk of melanoma has increased dramatically in recent decades. In the United States, there is a 1-in-87 chance of developing melanoma during one's life, an increase of 1,800 percent since 1930. Melanoma is the most frequent type of cancer among U.S. women aged 25 to 29 and the second most frequent among women aged 30 to 34.

Many other countries, including Australia, Austria, Canada, Germany, Italy, and Scotland have also experienced a rising rate of melanoma, according to the AAD. It has been suggested that depletion of the ozone in the stratosphere, which is a natural filter against UV rays, is responsible for the rise in the incidence of melanoma.

The top layer of the skin, called the epidermis, is thinnest in non-weight-bearing areas, thicker on the soles of the feet, and thickest where repeated pressure causes calluses, e.g., on the palms. Squamous cells are cells close to the surface. Basal cells are deeper beneath the surface.

Pigment is produced near the basal cells, and pigment production increases as the skin absorbs UV rays. As squamous cells multiply, they are pushed toward the skin surface, flattening as they move outward. These cells ultimately die and become the dense, toughened outer skin layer.

The basal layer of the skin contains column-shaped cells that form the supporting foundation for the epidermis. The basal cells in fair-skinned persons are especially susceptible to genetic damage as a result of UV-ray exposure. When a cell's genetic material is changed, the cell may begin to divide in an ungoverned way.

Randomly and rapidly dividing cells are the beginning of basal-cell carcinoma, the most common form of skin cancer. They form a growing cluster that presses on nearby normal cells, disrupts the distribution of nutrients to the normal cells, and leads ultimately to their death. As the basal cells continue to multiply, they outgrow their blood supply, and some begin to die.

BASAL-CELL CARCINOMA -- usually starts as a small growth of cells about 1 millimeter to 2 millimeters across on the surface of the skin that may have a tiny cluster of capillaries at the center. Gradually, the cells in the center die and slough away, and the ring of growing cancer cells slowly becomes larger. The tissue may take on a slight pink color. Various types of superficial (skin-surface) treatment can eradicate the cancerous growth at this stage.

SQUAMOUS-CELL CARCINOMA -- is a slow-growing type of cancer that can spread to other parts of the body if cancerous cells enter the bloodstream. This type of cancer is very dangerous, and it can appear initially as a small cluster of cells that forms a lesion, or sore, that does not heal.

The amount of pigment in an individual's skin is determined by heredity. The pigment protects against solar UV rays, and, accordingly, populations that have lived for many generations near the equator tend to have darker skins than those with a polar ancestry.

MELANOMA CELLS -- contain melanin, a dark brown-to-black pigment. Melanoma cells can stimulate growth in nearby capillaries, thereby bringing nourishment to the cancer cells. This ability to obtain nourishment, along with other attributes involving immunologic factors, leads to very rapidly spreading melanoma cancers.

Avoidance of excessive UV-ray exposure, especially by those who are at higher risk for developing skin cancer, is a primary preventive measure. Individuals with a genetically higher risk include those with very fair skin; those with blond or red hair; those with blue, hazel, or other light-colored eyes; and those whose fathers and mothers have shown a susceptibility to skin cancer.

Protective measures include wearing a broad-brimmed hat during daylight and using a solar-protective cream that has a sun-protection factor (SPF) rating of 15 or higher. The AAD and the U.S.-based Skin Cancer Foundation recommend that sunscreen be reapplied every 2 hours, even on cloudy days, and after swimming or perspiring. It's particularly important to avoid unprotected exposure to sunlight during the most intense period of sunshine, between 10 a.m. and 3 p.m.

WANT TO GET BACK IN SHAPE FAST?

I know, you've been putting it off. you've wanted to join the gym or start walking more... well that didn't happen. You should check out this weight loss book. It helped me lose 30 pounds!