This section is about the two most common types of skin cancer: basal cell carcinoma and squamous cell carcinoma. They are often called non-melanoma skin cancer. Melanoma is a different type of skin cancer. For more information, see the Melanoma section.
The skin is the largest organ of the body. It covers the body, protecting it from injury, regulating its temperature and controlling fluid loss. Skin, like all other body tissues, is made up of cells. Its two main layers are the epidermis and dermis.
This is the outer layer of the skin. It contains three types of cells:
Basal cells multiply constantly and the older cells move upwards into the epidermis. When they flatten out and form a layer they become known as squamous cells. The top layer of your skin is made up of dead skin cells, which eventually fall off. The three main types of skin cancer begin in the cells of the epidermis.
When skin is exposed to the sun, melanocytes make extra melanin to protect the skin from getting burnt. This is what causes skin to tan. Melanocytes are also in non-cancerous (benign) spots on the skin called moles or naevi. Most moles are brown, tan or pink in colour and round in shape.
This is the layer underneath the epidermis. It contains the roots of hairs, sweat glands, blood and lymph vessels, and nerves. Before a skin cancer can spread, it must first move into the dermis.
Skin cancer is the uncontrolled growth of abnormal cells in the skin.
There are other rare skin cancers, such as Merkel cell carcinoma, Kaposi sarcoma or T cell lymphoma of the skin, but these cancers are treated very differently from BCCs and SCCs. Call Cancer Council Helpline 13 11 20 for more details.
Basal cell carcinoma - pearly coloured dry, flat area or lump
Squamous cell carcinoma – red, thickened scaly spot
BCC makes up about 70% of non-melanoma skin cancers.
Often BCCs have no symptoms. They tend to grow slowly and don’t usually spread to other parts of the body. The earlier a BCC is found, the easier it will be to treat.
However, if a BCC is left untreated or grows larger than 5cm, it may grow deeper into the skin and damage nearby tissue. This may make treatment more difficult and increase the chance of the BCC returning.
It is possible to have more than one BCC at the same time; having one increases your risk of getting another.
SCC accounts for about 30% of non-melanoma skin cancers.
SCCs tend to grow quickly over several weeks or months. It is possible for SCCs to spread to other parts of the body if left untreated.
Bowen’s disease (also called squamous cell carcinoma in situ) looks like a red, scaly patch. It is an early form of skin cancer found in the outer layer of the skin (epidermis). If not treated, it can sometimes develop into a SCC.
Border irregularity - an existing spot that has changed in size or shape
|Colour variation – an existing spot that has changed in colour|
Australia has the highest rates of melanoma in the world, with over 12,500 cases diagnosed in 2012. Melanoma is considered the most serious type of skin cancer.
Left untreated, a melanoma may spread deeper into the skin where cancer cells can escape and be carried in lymph vessels or blood vessels to other parts of the body. The earlier melanoma is diagnosed, the better the chance of cure.
Not all spots that appear on your skin are cancerous. However, freckles, moles or sunspots are warning signs that your skin has had too much sun exposure and you may be at a greater risk of developing skin cancer.
|Dysplastic naevus – mole with uneven and irregular colour||Sunspot (solar keratose) – red, flat scaly skin that feels rough|
A mole (naevus) is a normal growth on the skin. Moles develop when the pigment-producing cells of the skin (melanocytes) grow in groups.
Moles are very common. Some people have many moles on their body – this can run in families. Overexposure to the sun, especially in childhood, can also lead to more moles growing on the skin.
Moles that have an irregular shape and an uneven colour are called dysplastic naevi. People with many dysplastic naevi are at greater risk of developing melanoma. If you have these moles, ask your doctor how to check your skin regularly for any changes to find new skin spots. If you notice any changes, see your doctor immediately.
Red, scaly spots on the skin that feel rough are called sunspots (solar keratoses). They usually occur in people aged over 40 on areas of skin frequently exposed to the sun, such as the head, neck, hands, forearms and legs. Rarely, solar keratoses may develop into SCC.
"I have quite a few irregular looking moles on my back and arms, so it gives me peace of mind to get them checked regularly." – Sally
Australia has among the highest rate of skin cancer in the world. About two in three Australians will be diagnosed with some form of skin cancer before the age of 70.
BCC and SCC are the most common types of non-melanoma skin cancer. In Australia, over 750,000 new cases of BCC and SCC are diagnosed and treated each year.
BCC can develop in young people, but is most common in people aged over 40. SCC occurs mostly in people aged over 50.Melanoma can occur in young people, but is more common in people over 40, especially men.
The main cause of skin cancer is exposure to ultraviolet (UV) radiation. The sun produces UV radiation but it can also come from other sources, such as solarium tanning machines. People that use a sunbed before age 35 have nearly a 60% greater risk of melanoma.Most parts of Australia have high levels of UV radiation all year-round. This radiation cannot be seen or felt, but can cause:
Skin cancer is related to two factors: a person’s total lifetime exposure to UV radiation, and the pattern of sun exposure they have had. Research suggests that while skin cells are often damaged in childhood, it may be sun exposure in adulthood that triggers these damaged cells to turn cancerous.
The UV Index shows the intensity of the sun’s UV radiation. An Index of 3 (moderate) or above indicates that UV levels are high enough to cause skin damage and sun protection is needed, for example wearing a hat, applying sunscreen and seeking shade.
The daily SunSmart UV Alert shows sun protection times for over 200 locations in Australia. It also forecasts the maximum UV Index. You can check the Alert on the weather page of most daily newspapers, or by using a free app for smartphones – see SunSmart App for iPhone and Android.
Anyone can develop skin cancer, regardless of their skin colour or general health. However, the risk is higher for people who have:
People with olive or very dark skin naturally have more protection against skin cancer because their skin produces more melanin than fair-skinned people. However, because UV radiation is so strong in Australia, very dark and oliveskinned people still need to protect their skin.
For more information about protecting your skin, visit the SunSmart website. Talk to your GP about your risks for skin cancer and about checking your skin.