What's a melanoma? And how can I spot one?

Melanomas are small cancers on the skin.

They're usually found in a spot that sees a lot of sun –  footballer Jarryd Roughead got his on his lip.

It's the fourth-most common cancer diagnosed in Australia, according to the Cancer Council.

We're a sunburnt country, full of pale people and are uniquely prone to skin cancer - in fact we have one of the highest incidences in the world.

Two-out-of-three of us will develop a skin cancer by the age of 70.

Luckily, two thirds of those cancers will be basal cell carcinomas, or squamous cell carcinomas which in most case will respond to treatment.

Only 1-2 per cent of all skin cancers are highly dangerous and aggressive melanomas.

What causes it?

The more time you spend in the sun, the higher your chances of developing skin cancer becomes. Photo: Andrew Quilty

UV exposure is the main risk factor.

Every time you suffer sunburn, there is a very slight risk one of your damaged cells could turn cancerous.

The more time you spend in the sun, the higher the risk.

Fair skin, freckles, light eye colour and red hair are all major risk factors as well, as they tend to increase your risk of burning.

What does it look like?

A typical, thin, invasive melanoma.

Generally a melanoma looks like a spot or blemish on your skin, or a mole.

Almost all moles on a person's body are non-cancerous, but it is important to check yourself over regularly so you spot any that might put you at risk.

A cancerous spot might look asymmetric, or like a spot with spreading or irregular edges.

Melanoma spots can have a number of different colours running through them.

A particularly good risk sign is if your mole changes in size or colour.

Can it spread?

Hawthorn footballer Jarryd Roughead has had a recurrence of his cancer. Photo: Getty Images

In most cases, skin cancers are detected and cut out early, before they have time to spread.

Cancers also tend to grow outwards first, rather than downwards.

If the cancer isn't spotted in time, it could have grown deep enough to reach the lymph system or bloodstream.

If that happens, there is a chance the cancer cells can spread throughout your body, growing new tumours on internal organs.

Known as stage-four melanoma, this used to be fatal, with only 25 per cent of people living longer than a year after diagnosis.

How is it treated?

Until five years ago, if surgeons couldn't cut out the melanoma, there weren't many other effective drug options.

Here's where we get to the good news.

Melanoma treatments have been revolutionised in the past five years.

We now have therapies that encourage the bodies' own immune system to attack the cancer, which has proved to be much more effective than surgery or radiotherapy.

How do I check for it?

People in high-risk groups should have annual check-ups. Photo: Craig Sillitoe

If you're in a high-risk group – if you have fair skin, work outside, or have lots of moles – the Cancer Council recommends annual checkups at the dermatologist.

For everyone else, self-checks are important. Here's how to do one:

• Undress completely and stand in good natural light.
• Start by checking your head, neck and scalp, including the insides of the ears.
• Use a hand-held mirror for hard-to-see places.
• Move onto the torso, checking the front, back and sides.
• Check your arms and fingers, including in between the fingers and the beds of your fingernails.
• Check your bum, genitals, legs and toes, including in between your toes and on the soles of your feet.

How do I prevent it?

In all the ways you would protect yourself from sunburn – a hat, glasses, sunblock, a shirt, and making sure to seek shade during the hottest parts of the day.