The skin is the body’s largest organ. It protects the organs inside your body from injury, infection, heat and ultraviolet light from the sun. The skin helps control your body temperature and gets rid of waste materials through the sweat glands. It also makes vitamin D and stores water and fat.

Roughly 90% of melanoma skin cancers are caused by exposure to ultraviolet radiation (UV rays) emitted from the sun or tanning beds. UV rays penetrate the skin and can damage the DNA below. In response, the body produces melanin that helps to protect the skin from further damage. This is how tanned skin is formed and why tanned skin is not healthy. If the damaged DNA does not repair itself properly, it can lead to skin cancer.


The skin has 2 main layers:

  • the epidermis is the layer at the surface
  • the dermis is below the epidermis

The epidermis is made up of 3 types of cells:

  • Basal cells are continually being made deep in the epidermis. Newly made round basal cells push the older cells toward the surface of the skin to become squamous cells.
  • Squamous cells are old cells. As they move toward the skin’s surface, they become thin and flat.
  • Melanocytes are also found deep in the epidermis, in between the basal cells. Melanocytes are cells that make melanin, which gives colour to your skin.

The dermis contains:

  • nerves
  • blood vessels
  • sweat glands
  • oil glands
  • hair follicles

Common types of skin cancer

The most common types of skin cancer are squamous cell cancer and basal cell cancer. Both are known as non-melanoma skin cancer and they can usually be treated successfully.


Melanoma, which can spread in the body, is a less common but most dangerous form of skin cancer.

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