Skin Cancer I: Causes

Posted by Chad Melius on Saturday 7 March 2009

Who can get skin cancer?

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Anybody can get skin cancer. Some people are genetically more susceptible, but noone is immune. Ultraviolet radiation from the sun is what causes skin cancer. And you are exposed to sunlight every time you go outdoors.

Lots of people like to lie outside in the sun, in order to get a nice suntan. They may think that all they’re risking is a sunburn, which will go away in a few days time. But this is just wishful thinking – they’re really risking skin cancer, which can lie dormant for years.

Types of ultraviolet radiation

Picture courtesy of Best UV -
Electromagnetic Spectrum

Ultraviolet radiation is not light. It is a type of electromagnetic radiation that has a shorter wavelength than visible radiation ( light ). Just as light has different colors, UV radiation has different types.

  • UVC: This is most dangerous type of UV radiation, but fortunately it is blocked by being absorbed by molecules in the upper layers of the Earth’s atmosphere.
  • UVB: This radiation is what causes tanning, by forming melanin in the outer layers of the skin. For many years, type B UV rays were thought to be the cause of skin cancer. So protective devices like suncream, umbrellas, and clothing were designed to block these rays.
  • UVA: This longer wavelength radiation is now known to do more damage to the skin than type B radiation. It can even pass through glass and light clothing. So protective devices must now be able to block this type of radiation in order to be effective in preventing sun cancer.

Types of skin cancer

Picture courtesy of the National Cancer Institute -
Layers of the Skin

Skin cancers come in three different varieties, which differ in their location and malignancy.

  • Basal cell carcinoma: This is the most common form of skin cancer, and is the least dangerous. It forms in the bottom layer of the skin, and erupts to the surface, often forming a scab and bleeding. Many people erroneously think of it as a sore that doesn’t heal.
  • Squamous cell carcinoma: These relatively uncommon cancers develop in the middle section of the epidermis. If left untreated, they can grow to quite a large size. This type of carcinoma can migrate to other parts of the body, and can be fatal if untreated.
  • Melanoma: This cancer occurs in the outer layer of the skin, in the cells that produce melanin ( the dark pigment that causes suntan ). It is the most aggressive type of skin cancer, the most likely to metastasize ( spread ), and will cause death if untreated. Recent studies have shown that is primarily caused by UV-A radiation.
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Basal Cell Carcinoma

Now that you have a pretty good idea of what causes skin cancer, what can you do to prevent it? In the next chapter we will discuss how to tell if you have it, how to prevent it, and what to do if you get it.

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