What is Cancer
Cancer Types

Skin cancers (non-melanoma)

The skin
The skin is the largest organ in the body. It covers the body, protecting it from injury, regulating its temperature and preventing it from becoming dehydrated. Skin, like all other body tissues, is made up of cells. It has two main layers called the epidermis and the dermis.
 
Epidermis
This is the top, outer layer of the skin. It contains three different kinds of cells:
  • Squamous cells: flat cells that are packed tightly to make up the top layer
  • Basal cells: tall cells that make up the lower layer
  • Melanocytes: cells that produce a dark pigment called melanin, the substance that gives skin its colour
Basal cells multiply constantly and the older cells move upwards in the epidermis. When they flatten out and form a layer they become squamous cells. The top layer of your skin is made up of dead skin cells which eventually fall off.
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.
 
Dermis
This is the layer underneath the epidermis. It contains the roots of hairs, sweat glands, blood and lymph vessels and nerves.
 
What is skin cancer?
Skin cancer is the uncontrolled growth of abnormal cells in the skin.
What types are there?
There are three main types of skin cancer: basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), which are called non-melanoma skin cancers, and melanoma. There are other rare skin cancers, such as those that start in the sweat glands and hair follicles.
Melanoma is not discussed in detail here, refer to our melanoma page.
 
Basal Cell Carcinoma (BCC)
BCC makes up about 70% of non-melanoma skin cancers.
  • It commonly develops on the head, neck and upper body.
  • It may appear as a pearly lump or a scaly or dry area that is pale or bright pink in colour and shiny.
  • BCC may bleed and become inflamed, and dead tissue may slough off (ulcerate). Some BCCs heal, then break down again.
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 BCC is left untreated or grows larger than 5 cm, 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.
 
Squamous Cell Carcinoma (SCC)
SCC accounts for about 30% of non-melanoma skin cancers.
  • SCC usually appears on parts of the body most often exposed to the sun, such as the head, neck, hands, forearms or lower legs.
  • It often appears as a thickened, red, scaly spot and may look like a sore that hasn't healed.
  • It may be tender to touch.
SCCs tend to grow quickly over several weeks or months. It is possible for SCCs to spread to other parts of the body – particularly the lips, ears, scalp or temples – if left untreated.
 
Non-melanoma skin cancers
Bowen's disease looks like a red, scaly patch. It is an early skin cancer found in the outer layer of the skin (epidermis) and is often called squamous cell carcinoma in-situ.

Melanoma
Melanoma is the least common type of skin cancer but it is the most serious.
  • It can often appear as a new spot or an existing spot that changes size, shape or colour.
  • Melanoma often has an irregular edge or surface, and it may be more than one colour such as brown, black, blue, red, white or light grey.
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.

Melanoma Skin Cancers
How common is it ?
According to Globocan (2012), melanoma of the skin affects 0.3% of Malaysians, with a higher incidence in Malaysian males compared to females. 
Data from the Dermatology Clinic, Hospital Kuala Lumpur (2006-2014), showed that basal cell carcinoma is the most common type of skin cancer in Malaysia, accounting for 34.9% of cases. This was followed by cutaneous lymphoma in 25.7% of patients and squamous cell carcinoma in 20.6% of cases.
Causes
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.
 
UV radiation cannot be seen or felt but can cause sunburn, skin and eye damage,
premature ageing of the skin, damage to the skin cells, which leads to skin cancer.
 
Skin cancer is related to two factors: a person’s total lifetime exposure to UV radiation and the pattern of 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
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.
Who is at risk?
Anyone can develop skin cancer, regardless of their skin colour or general health. However, the risk is higher for people who have numerous moles on their body, dysplastic naevi, a personal or family history of melanoma, actively tanned or used solariums or sun beds, fair skin that burns easily, freckles and doesn't tan, experienced short, intense periods of exposure to UV radiation (such as on holidays or during sport), worked outdoors, red or fair hair and blue or green eyes, a weakened immune system, which could be due to taking certain drugs that suppress the immune system.
 
People with olive or very dark skin have more natural protection against skin cancer because their skin produces more melanin than fair-skinned people.
 
What about spots that aren't cancer?
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 greater risk of developing skin cancer.
 
Moles (naevi)
A mole (naevus) is a normal growth on the skin. Moles (naevi) 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 and this can run in families. Overexposure to the sun, especially in childhood, can also lead to more moles growing on the skin.
 
Dysplastic naevi
Moles that have an irregular shape and an uneven colour are called dysplastic naevi. People with many dysplastic naevi are at a higher risk of developing melanoma. If you have these moles, check your skin regularly for any changes and look for new skin spots. If you notice any changes, see your doctor immediately.
 
Sunspots (solar keratoses)
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 exposed to the sun, such as the head, neck, hands, forearms and legs. Rarely, solar keratoses may develop into squamous cell carcinoma.
Information Reviewed By:
Dr Andrew Satchell, Dermatologist, Royal Prince Alfred Hospital and Dubbo Dermatology; Irena Brozek, Research and Development Officer - Sun, Cancer Council NSW; Dr Alvin Chong, Senior Lecturer in Dermatology, Skin and Cancer Foundation Victoria and The University of Melbourne; Trevor Munn, Consumer; Neva Sperling, Consumer; Monica Tucker, Cancer Information Consultant, Cancer Council Helpline; Margaret Whitton, Clinical Nurse Consultant, Department of Dermatology, Royal Prince Alfred Hospital, members of the SunSmart Victoria team and Carole Arbuckle,