Grease star Olivia Newton John announces third cancer battle

Elaine developed a small mole on her cheek, but years later a friend said it looked different. That's why you need to check your moles every month. It's a good idea to take photos too, because you see yourself every day and may miss changes. If you're not sure, show your mum, sister or friend. Also check places like your back, bum, scalp, soles of your feet, and between your fingers.

If several relatives have had skin cancer, you're more likely to get it too, so any mole that looks suspicious should be checked. Elaine is fair-skinned, which also ups the risk, but nobody – whatever their skin type – should use sunbeds, and nobody should get burned. Burned skin is a sign you've damaged your DNA and that's a cancer risk.If you have more than 11 moles on your right arm, or any really big ones (bigger than 6mm across), your risk is increased too. If having lots of moles makes it hard to check them, you could use an app like SkinVision or Miiskin, or even pay for a mole mapping service. They cost about £150 – but if you've spent years using sunbeds, it could be a wise investment.

A healthy mole should be even, so both halves look the same, and the edges should be sharp – not jagged or blurred – and it should be one colour, not bigger than 6mm across and it shouldn't change. If it does, see your GP. Symptoms can take 20 years to develop, and can be caused by being burned from as far back as childhood. If you remember being as red as a lobster on childhood holidays, you need to keep checking your moles.

Sunbeds can give out UV rays stronger than midday tropical sun, so don't think that because it's a nice machine in a shiny salon it's safe or medicalised. Those rays can also damage your eyes, so look out for dark spots or changes in your vision.Melanoma is the third most common cancer in the UK and the earlier you spot it, the easier it is to treat, so make checking your moles a monthly habit.