Melanoma skin cancer
Melanoma is a type of skin cancer. It develops in the skin cells called melanocytes and usually occurs on parts of the body that have been overexposed to the sun.
Rarely, melanomas can also start inside the eye or in a part of the skin or body that has never been exposed to the sun, such as mucous membranes (e.g. sinuses, digestive tract, genitals), the soles of the feet or palms of the hands, and under the nails.
Learn more about:
- Types of skin cancer
- The skin
- Who gets melanoma
- The main types of melanoma
- What causes melanoma
- Why is sun protection important?
- Having a family history of melanoma
Types of skin cancer
Melanoma is not the only type of skin cancer. Other types of skin cancer include basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). These are known as non-melanoma skin cancers or keratinocyte cancers, and they are far more common than melanoma.
However, melanoma is considered the most serious form of skin cancer because it is more likely to spread to other parts of the body, especially if not found early. The earlier melanoma is found, the more successful treatment is likely to be.
This information is about melanoma. For information about non-melanoma skin cancers (basal cell or squamous cell carcinomas), see Skin cancer.
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 the dermis. Below these is a layer of fatty tissue.
The epidermis is the top, outer layer of the skin. It contains three main kinds of cells:
These flat cells are packed tightly together to make up the top layer of skin and form the thickest layer of the epidermis. These cells eventually die and become the surface of the skin. Over time, the body sheds these dead skin cells.
These block-like cells make up the lower layer of the epidermis and multiply constantly. As they age, they move up within the epidermis and flatten out to form squamous cells.
These cells sit between the basal cells and produce a dark pigment called melanin, the substance that gives skin its colour. When skin is exposed to ultraviolet (UV) radiation, melanocytes make extra melanin to try 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.
The dermis is the layer of skin that sits below the epidermis. It is made up of fibrous tissue and contains hair roots (follicles), sweat glands, blood vessels, lymph vessels and nerves.
Layers of the skin
Who gets melanoma?
Australia and New Zealand have the highest rates of melanoma in the world. Every year, about 16,000 people are diagnosed with melanoma in Australia.
Melanoma is the second most common cancer in men and the third most common cancer in women (excluding non-melanoma skin cancers).
What are the main types of melanoma?
Melanoma of the skin is known as cutaneous melanoma. The main subtypes of cutaneous melanoma are:
Superficial spreading melanoma
|How common?||Makes up 55–60% of all melanomas.|
|Who gets it?||Most common type of melanoma in people under 40, but can occur at any age.|
|What does it look like?||Can start as a new brown or black spot that grows on the skin, or as an existing spot, freckle or mole that changes size, colour or shape.|
|Where is it found?||Can develop on any part of the body but especially the trunk.|
|How does it grow?||Often grows slowly and becomes more dangerous when it invades the lower layer of the skin (dermis).|
|How common?||Makes up about 10–15% of melanomas.|
|Who gets it?||Most commonly found in people over 65.|
|What does it look like?||Usually appears as a round, raised lump (nodule) on the skin that is pink, red, brown or black and feels firm to touch; may develop a crusty surface that bleeds easily.|
|Where is it found?||Usually found on sun-damaged skin on the head and neck.|
|How does it grow?||Fast-growing form of melanoma, spreading quickly into the lower layer of the skin (dermis).|
Lentigo maligna melanoma
|How common?||Makes up about 10–15% of melanomas.|
|Who gets it?||Most people with this subtype are over 40.|
|What does it look like?||Begins as a large coloured spot (lentigo maligna).|
|Where is it found?||Mostly found on sun-damaged skin on the face, ears, neck or head.|
|How does it grow?||May grow slowly and superficially over many years before it grows deeper into the skin.|
Acral lentiginous melanoma
|How common?||Makes up about 1–2% of all cases.|
|Who gets it?||Mostly affects people over 40.|
|What does it look like?||Often appears as a colourless or lightly coloured
area, may be mistaken for a stain, bruise or unusual wart; in the nails, can look like a long streak of pigment.
|Where is it found?||Most commonly found on the palms of the hands or on the soles of the feet, or under the fingernails or toenails.|
|How does it grow?||Tends to grow slowly until it invades the lower layer of the skin (dermis).|
|How common?||Makes up about 1–2% of all cases.|
|Who gets it?||Mostly affects people over 60.|
|What does it look like?||Starts as a firm, growing lump, often the same colour as your skin; may be mistaken for a scar and can be difficult to diagnose.|
|Where is it found?||Mostly found on sun-damaged skin on the head or neck.|
|How does it grow?||Tends to be slower to spread than other subtypes, but often diagnosed later.|
Other types of melanoma
Some rarer types of melanoma start in other parts of the body. Mucosal melanoma can start in the tissues in the mouth, anus, urethra, vagina or nasal passages. Ocular melanoma can start inside the eye. Melanoma can also start in the central nervous system.
Call Cancer Council 13 11 20 for information about rarer types of melanoma.
For an overview of what to expect at every stage of your cancer care, visit Cancer Pathways – Melanoma. This is a short guide to what is recommended, from diagnosis to treatment and beyond.
What causes melanoma?
The main cause of all types of skin cancer is overexposure to ultraviolet (UV) radiation.
UV radiation most often comes from the sun, but it can also come from artificial sources such as solariums (also known as tanning beds or sun lamps). Solariums are now banned for commercial use in Australia because research shows that people who use solariums have a much greater risk of developing melanoma.
Anyone can develop melanoma. The risk is higher in people who have:
- unprotected exposure to UV radiation, particularly a pattern of short, intense periods of sun exposure and sunburn, such as on weekends and holidays
- lots of moles (naevi) – more than 10 moles above the elbow on the arms and more than 50 on the body, especially if the moles have an irregular shape and uneven colour (dysplastic naevi)
- pale, fair or freckled skin, especially if it burns easily and doesn’t tan
- light-coloured eyes (blue or green), and fair or red hair
- a previous melanoma or other type of skin cancer
- a strong family history of melanoma
- a weakened immune system from using immunosuppressive medicines for a long time (e.g. for rheumatoid arthritis or another autoimmune disease or after an organ transplant).
Why is sun protection important?
When your unprotected skin is exposed to the sun or other UV radiation, the structure and behaviour of the cells can change. This can permanently damage the skin, and the damage adds up over time.
Being exposed to too much UV radiation as a child increases the risk of skin cancer later in life, although sun protection will help prevent melanoma at any age.
Learn more about protecting your skin from overexposure to the sun and sun damage.
Family history of melanoma
Sometimes melanoma runs in families. Often, this is because family members have a similar skin type or a similar pattern of sun exposure in childhood.
Only 1–2% of melanomas in Australia involve an inherited faulty gene. Some of these genes have been identified.
If two or more close relatives (parent, sibling or child) have been diagnosed with melanoma, they may have an inherited faulty gene. This is especially the case if they are diagnosed with more than one melanoma on different areas of the skin, or if they are diagnosed with melanoma before the age of 40.
People with a strong family history of melanoma should protect and monitor their skin themselves, and have a professional skin check by a doctor every year from their early 20s. New moles or skin spots after this age should be investigated.
If you are concerned about your family risk factors, talk to your doctor about having regular skin checks or ask for a referral to a family cancer clinic. Visit the Centre for Genetics Education to find a family cancer clinic near you.
To find out more, call Cancer Council 13 11 20.
A/Prof Robyn Saw, Surgical Oncologist, Melanoma Institute Australia, The University of Sydney and Royal Prince Alfred Hospital, NSW; Craig Brewer, Consumer; Prof Bryan Burmeister, Radiation Oncologist, GenesisCare Fraser Coast and Hervey Bay Hospital, QLD; Tamara Dawson, Consumer, Melanoma & Skin Cancer Advocacy Network; Prof Georgina Long, Co-Medical Director, Melanoma Institute Australia, and Chair, Melanoma Medical Oncology and Translational Research, Melanoma Institute Australia, The University of Sydney and Royal North Shore Hospital, NSW; A/Prof Alexander Menzies, Medical Oncologist, Melanoma Institute Australia, The University of Sydney, Royal North Shore and Mater Hospitals, NSW; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; Paige Preston, Chair, Cancer Council’s National Skin Cancer Committee, Cancer Council Australia; Prof H Peter Soyer, Chair in Dermatology and Director, Dermatology Research Centre, The University of Queensland Diamantina Institute, and Director, Dermatology Department, Princess Alexandra Hospital, QLD; Julie Teraci, Clinical Nurse Consultant and Coordinator, WA Kirkbride Melanoma Advisory Service, WA.
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