Skin cancer

Skin cancer is the uncontrolled growth of abnormal cells in the skin.

Learn more about:

• The skin
• Types of skin cancer
• The signs of skin cancer
• The signs of non-cancerous skin spots
• Other skin spots
• What causes skin cancer?
• Who is at risk?
• How common is skin cancer?
• How to spot a skin cancer?
• How to check your skin

The skin

The skin is the largest organ of the body. It acts as a barrier to protect the body from injury, control body temperature and prevent loss of body fluids. The two main layers of the skin are the epidermis and dermis. Below these is a layer of fatty tissue.

The layers of the skin

Epidermis

This is the top, outer layer of the skin. It is made up of several cell types:

Dermis

This layer of the skin sits below the epidermis. The dermis contains the roots of hairs (follicles), sweat glands, blood vessels, lymph vessels and nerves. All of these are held in place by collagen and elastin, the proteins that give skin its strength and elasticity.

Types of skin cancer

The three main types of skin cancer are basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma. BCC and SCC are also called non-melanoma skin cancer or keratinocyte cancers. Learn more about the signs to look for.

Rare types of non-melanoma skin cancer include Merkel cell carcinoma and angiosarcoma. They are treated differently from BCC and SCC. Call Cancer Council 13 11 20 to find out more about rarer skin cancers.

Basal cell carcinoma (BCC)

This starts in the basal cells of the epidermis. It makes up about 70% of non-melanoma skin cancers.

BCC grows slowly over months or years and rarely spreads to other parts of the body. The earlier a BCC is diagnosed, the easier it is to treat. If left untreated, it can grow deeper into the skin and damage nearby tissue, making treatment more difficult.

Having one BCC increases the risk of getting another. It is possible to have more than one BCC at the same time on different parts of the body.

Squamous cell carcinoma (SCC)

This starts in the squamous cells of the epidermis. It makes up about 30% of non-melanoma skin cancers.

SCC tends to grow quickly over several weeks or months. If left untreated, SCC can spread to other parts of the body. This is known as invasive SCC. SCC on the lips and ears is more likely to spread.

Melanoma

This starts in the melanocyte cells of the skin. It makes up 1–2% of all skin cancers.

Although melanoma is a less common type of skin cancer, it is considered the most serious because it grows quickly and is more likely to spread to other parts of the body, such as the lymph nodes, lungs, liver, brain and bones, especially if not found early. The earlier melanoma is found, the more successful treatment is likely to be.

For more on this, see Melanoma.

What causes skin cancer

The main cause of all types of skin cancer is overexposure to UV radiation. Over 95% of skin cancers are caused by UV exposure. When unprotected skin is exposed to UV radiation, the structure and behaviour of the cells can change.

UV radiation is produced by the sun, but it can also come from artificial sources, such as the lights used in solariums (sun beds). Solariums are now banned in Australia for commercial use because research shows that people who use solariums have a high risk of developing skin cancer.

Most parts of Australia have high levels of UV radiation all year round. UV radiation cannot be seen or felt and it is not related to temperature. It can cause:

• sunburn
• premature skin ageing
• damage to skin cells, which can lead to skin cancer.

Find out how to protect yourself from the sun and prevent skin cancer from occurring.

Who is at risk?

Anyone can develop skin cancer, but it’s more common in older people. The risk is also higher in people who have:

• fair or freckled skin, especially if it burns easily and doesn’t tan
• red or fair hair and light-coloured eyes (blue or green)
• had short, intense periods of exposure to UV radiation, e.g. on weekends or holidays or when playing sport, especially if it caused sunburn
• actively tanned or used solariums
• worked outdoors
• a weakened immune system, which could be caused by taking certain medicines after an organ transplant (immunosuppressants) or by ongoing blood conditions such as chronic leukaemia
• lots of moles on their body or moles with an irregular shape and uneven colour (dysplastic naevi)
• a previous skin cancer or a family history of skin cancer
• certain skin conditions such as sunspots.

People with olive or very dark skin have more protection against UV radiation because their skin produces more melanin than fair skin does. However, they can still develop skin cancer.

How common is skin cancer?

Australia has one of the highest rates of skin cancer in the world. Skin cancer is the most common cancer diagnosed in Australia. About two in three Australians will be diagnosed with some form of skin cancer before the age of 70.

Almost 980,000 new cases of BCC and SCC are treated each year. BCC can develop in young people, but it is more common in people over 40. SCC occurs mostly in people over 50.

More than 13,000 people are diagnosed with melanoma in Australia every year. Australia and New Zealand have the highest rates of melanoma in the world.