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  • What is melanoma?

    Last reviewed October 2012

    Contents

    Melanoma is a type of skin cancer. There are three main types of skin cancer that are named after the cells that are affected: squamous cell carcinoma, basal cell carcinoma and melanoma (which starts from melanocytes).

    Melanoma is the least common skin cancer but it is the most serious because it can grow quickly. If melanoma isn’t treated it may spread to the deeper layer of skin (dermis) where cancer cells can escape to other parts of the body.

    Although melanoma usually arises in the skin, it is also possible for it to form in melanocytes in other parts of the body such as the nervous system, eye and mucous membranes (e.g. lining of the mouth and nasal passages).

    Types of melanoma

    Skin melanomas are called cutaneous melanomas. Cutaneous melanomas are categorised by how thick they are, how far they have spread and the way they look.

    Superficial spreading melanoma

    This is the most common type of melanoma, making up almost 50 per cent of all cases. It starts as a brown or black spot that grows like a spreading stain on the outer layer of the skin (epidermis). This type of melanoma becomes dangerous when it invades the lower layer of the skin (dermis).

    Nodular melanoma

    Makes up about 15 per cent of melanomas. It is usually a raised lump on the surface of the skin that is very dark brownish black or black in colour. However nodular melanoma can sometimes be pink or red or have no pigment at all.

    Lentigo maligna melanoma (LMM)

    This type of melanoma is most common in the elderly population. It makes up about 10 per cent of melanomas.

    LMM begins as a large freckle (a lentigo maligna) in an area of skin that has had a lot of sun exposure, such as the face or upper body. It may grow slowly and superficially over many years until it penetrates more deeply into the skin.

    Acral lentiginous melanoma

    A rare type of melanoma that is most commonly found on the palms of the hands, soles of the feet or under the nails.

    Other types of melanoma

    There are some other rarer types of melanoma that affect the skin, such as desmoplastic or amelanotic melanoma. For more information about these types of melanoma or about melanoma of the nervous system, eye or mucous membranes, talk to your medical team or call the Cancer Council Helpline.

    Signs and symptoms of melanoma

    Melanomas can vary greatly in the way they look. The first sign of a melanoma is usually a change in an existing mole or the appearance of a new spot.

    Size
    The spot may begin to get or keep getting, larger

    Colour
    The mole may appear blotchy with a wide variety of colours such as brown, black, blue, red, white and/or grey

    Shape/border
    An irregular edge (scalloped or notched) or lack of symmetry is a warning sign. That is, if a line was drawn through the middle of the mole, the two sides would not match up. The spot may increase in height or become scaly.

    A mole that itches from time to time or bleeds may indicate a change to melanoma.

    It is normal for new moles to appear and change during childhood and pregnancy. However all adults who have a new mole should get it examined. Even if you have had a mole checked before and it was assessed as benign, keep an eye on it because it could change in the future. Talk to your doctor immediately about any changes.

    Melanoma can occur anywhere on the body. In men it most commonly develops on the back. Women get more melanomas on their legs than men.

    How common is it?

    Australia has the highest rate of melanoma in the world.

    Melanoma of the skin is the second most common cancer in men and the third most common cancer in women. It is the most common type of cancer in adolescents and young adults (19% of all cases) and middle-aged men (25–54 years).

    Who is at risk?

    The following factors may increase a person’s risk of developing melanoma:

    Sensitive skin
    Some people have skin that is more sensitive to UV radiation. This includes people who have pale or fair skin, people who burn easily and don’t tan, and people with light-coloured eyes.

    Having several moles
    Adults with more than 10 moles on their arms and more than 50 on their body should have their skin checked regularly by their GP or a dermatologist (skin specialist).

    Childhood tanning/sunburning
    Excessive sun exposure before the age of 15 greatly increases the chance of getting melanoma in later life because damaged cells have more time to develop into cancer.

    Fair-skinned people who migrate to Australia after the age of 13 have only a third of the risk of melanoma compared to people born in Australia.

    UV exposure
    People who occasionally get heavy sun exposure (e.g. on weekends or on holidays) may be at particular risk, especially if they get sunburnt. People who are frequently exposed to UV rays through regular sun exposure or solarium use are also at risk.

    Age
    Melanoma is most common in people more than 50 years of age.

    Cancer history
    A person who has had melanoma or another type of skin cancer (BCC or SCC) is at an increased risk.

    Family history
    Melanoma is a common disease – many people have a family member who has developed melanoma. For most people this is due to non-inherited factors (such as having a similar amount of sun exposure) or chance. However in a small proportion of people (five to 10 per cent), there may be an inherited faulty gene in their family that contributes to the development of cancer.

    Your family may have an inherited the faulty gene if two or more people on the same side of the family (e.g. mother’s or father’s side) have been diagnosed with melanoma, plus there is an additional risk factor. Another risk factor may be a first degree relative who has had more than one melanoma on different areas of the skin or someone who has been diagnosed with melanoma before the age of 40.

    If you are concerned that you have family risk factors, talk to your doctor about having regular skin checks or ask for a referral to a family cancer clinic. Call Cancer Council Helpline for more information.

    The causes of melanoma

    The main cause of all types of skin cancers is exposure to ultraviolet (UV) radiation from the sun or another source, such as a solarium tanning machine. Each time your unprotected skin is exposed to UV radiation, it changes the structure of the cells and what they do.

    Research shows that people who first use tanning machines (solariums) before age 35 have a 98 per cent higher risk of developing melanoma.

    Exposure to UV radiation permanently damages the skin. This damage adds up over time. The most important years for sun protection are during childhood.

    Sometimes melanoma happens by chance and sun exposure doesn’t seem to play a role.

    Useful websites

    Melanoma Patients Australia: www.melanomapatients.org.au
    Melanoma Institute Australia: www.melanoma.org.au
    Sydney Melanoma Diagnostic Centre: www.melanoma.net.au

    Information reviewed by: : Prof Grant McArthur, Consultant Medical Oncologist, Head of the Translational Research Group and Head of the Molecular Oncology Laboratory, Peter MacCallum Cancer Centre, VIC; Jay Allen, Consumer and Community Coordinator, Melanoma Institute Australia, NSW; Annie Angle, Cancer Council Helpline Nurse, Cancer Council Victoria; Prof Michael P Brown, Director, Cancer Clinical Trials Unit, Senior Medical Oncologist, Royal Adelaide Cancer Centre, SA; Dr Vanessa Estall, Head Radiation Oncologist, Melanoma and Skin Service, Peter MacCallum Cancer Centre, VIC; Clinton Heal, Consumer and CEO and Founder of Melanoma WA; Prof John Thompson, Professor of Melanoma and Surgical Oncology at the University of Sydney and Director, Melanoma Institute Australia, NSW; and members of the SunSmart Victoria team. 

     

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