What is skin cancer?

There are 2 main types of skin cancer: Non melanoma skin cancer and melanoma skin cancer. 

Non melanoma skin cancer includes:

  • basal cell skin cancer - this is also called basal cell carcinoma (BCC)
  • squamous cell skin cancer - this is also called squamous cell carcinoma (SCC)
  • some other rare types

This section is about non melanoma skin cancer. 

Non melanoma skin cancers tend to develop most often on skin that's exposed to the sun. There is a high cure rate for these cancers. Most people only have minor surgery and don't need further treatment.

It is important that you check your skin regularly.

The skin and what it does

The skin does several jobs including:

  • protecting the inside of the body from damage
  • helping to keep our body temperature more or less the same
  • getting rid of some body waste products through sweat
  • making vitamin D (this helps form and maintain our bones)
Diagram showing the structure of the skin

The skin is made up of 2 main layers: the epidermis on the outside and the dermis beneath.

The thickness of the epidermis and the dermis varies depending on the part of the body the skin is covering. For example, the skin on the sole of your foot is quite thick, about 5mm. The skin on your eyelid is much thinner, only about 0.5mm.

The cells of the skin

Sun damage is the cause of most skin cancers. The cells in the epidermis are most at risk of sun damage.

The most common type of cells found in the epidermis are called keratinocytes. Basal cells are a type of keratinocyte found at the bottom of the epidermis. The basal layer is where all normal skin cells come from, and where basal cell skin cancer develops. This is also called basal cell carcinoma (BCC).

BCC is the most common type of skin cancer. It mostly develops in areas of skin exposed to the sun such as the head, face, ears and neck. 

The top 2 layers of the skin are made up of cells that have died and pushed up from the basal layer. They're filled with keratin made from keratinocytes. It's a tough waxy substance that helps to make the skin strong to protect the body.

Squamous cell skin cancer also develops from keratinocytes in the epidermis. This is also called squamous cell carcinoma (SCC). These cancers develop in the cell layer just above the basal layer.

Melanoma skin cancer starts in the skin cells called melanocytes. These are cells in the deeper layers of the epidermis. Melanocytes make melanin. This is the brown substance (pigment) that makes skin look darker. The melanocytes produce melanin when the skin is exposed to the sun. 

Diagram showing the types of cells in the epidermis

Skin cancers can grow slowly and it can take some years before a cancer is noticed. But sometimes a skin cancer can grow very quickly, within a few months.

Contact your GP if you have an area of skin such as a spot, sore, ulcer or lesion that you are worried about or has not healed after 4 weeks.

Who gets it?

Most skin cancers are caused by exposure to the sun. This may be long term exposure, or short periods of intense sun exposure and burning. There are several factors that affect your risk from sun exposure including:

  • how much time you spend outdoors
  • your natural skin colour

Sun exposure can also be in the form of sunbeds (artificial UV radiation). People who use sunbeds are also at risk of developing skin cancer.

Age is also a factor. The older you are, the more likely you are to get non melanoma skin cancer. 

How common is it?

Around 156,000 cases of non melanoma skin cancer are diagnosed in the UK each year. The number could be higher as we know that they are under reported. This makes it the most common type of cancer by far. Because non melanoma skin cancers are easy to treat and cure, they're often left out of national cancer statistics.

Related links