The 5 ‘silent' cancer signs you might miss on your nails – plus the ‘diamond gap test' & other deadly hand clues

The Sun

27-06-2025

IF you love a bit of sun, you might know to check your skin for worrying moles, blemishes and marks.
But did you know that the deadly skin cancer, melanoma, can develop in obscure places? On or around your nails. Here's how to spot the lesser-known signs.
With the Met Office predicting temperatures could hit 30C in places this weekend, it's not just new or evolving moles you need to look out for, but warning signs in your fingernails and toenails too.
Dr Magnus Lynch, consultant dermatologist, tells Sun Health: "Changes in your fingernails can be an early warning sign of cancer.
"This is because nails reflect what's going on inside the body, including how it's using oxygen and nutrients, and fighting disease."
Melanoma is the fifth most common cancer in the UK, and rates are steadily rising, according to Cancer Research UK.
It's usually caused by UV light from the sun, which can damage the DNA in skin cells and trigger abnormal growth.
And though it's rare for skin cancer - including melanoma - to develop under and around your fingernails and toenails, it does happen.
It tends to be more common in people of colour, and if you're older, according to the American Academy of Dermatology Association (AAD).
You could also be at risk if you have a family history of melanoma or you've injured your nails in the past.
There are five signs to watch out for on and around your nails that could indicate you have melanoma.
Dr Leyla Hannbeck, chief executive of the Association of Independent Multiple Pharmacies, adds: "While not all these symptoms mean cancer, it's important to get them checked out, as early detection is crucial."
1. A dark streak
This may look like a brown or black band on your nail, the AAD said.
It's most likely to show up on the thumb or big toe of your dominant hand or foot. However, the discolouration could develop on any one of your nails.
A woman recently took to TikTok to recount how a 'cool' nail streak she'd had for 10 years - which looked like a brown line painted across her nail - turned out to be a sign of subungual melanoma.
People who have melanoma under their nail may wrongly believe they just have bruising, or not even notice a change at all. Aside from a line, it can also look like irregular pigmentation under the nail.
Maria Sylvia revealed that her own dark streak grew from the nailbed, where a cancerous mole sat.
2. Your nail lifting from your fingers or toes
You might think you've just stubbed your toe, but a nail peeling or lifting off from the skin might be the sign of something more sinister, according to the AAD.
It explained: "When this happens, your nail starts to separate from the nail bed.
"The white free edge at the top of your nail will start to look longer as the nail lifts."
3. Your nail splitting
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Your nail splitting down the middle is yet another possible sign of melanoma.
This is because the cancer can weaken the nail plate, causing it to crack or split, according to the Cleveland Clinic.
4. A bump or nodule under your nails
Pay attention if you notice something bumpy under your nail.
You might also see a band of colour on your nail.
It could be wide and irregular or dark and narrow, the American Academy of Dermatology explains.
5. Thick nail
A thickened bit under your nail could be a warning sign of a rare genetic condition that raises the risk of several cancers, a study published last year found.
The disorder, called BAP1 tumour predisposition syndrome, affects a gene that normally helps stop cells from growing out of control and turning cancerous.
It also plays a key role in fixing damaged DNA.
People with the condition face a higher risk of tumours in the skin - like melanoma - eyes, kidneys, and the lining of the chest and abdomen.
What to do if your nails look dodgy
Nail melanoma is often diagnosed at a more advanced stage than melanoma on the skin, according to the AAD.
It advised you to see a dermatologist if you notice changes to your nails.
"The good news is that when found early, melanoma - even on the nails - is highly treatable," the AAD said.
So it's useful to know what to look for and to regularly check your nails.
Laura Harker, a screening nurse at The MOLE Clinic, advised to also keep an eye on other less obvious areas, such as your hairline, behind the ears, the soles of your feet and your arms.
There are two main types of skin cancer.
Non-melanoma skin cancers are diagnosed a combined 147,000 times a year in the UK, while melanoma, the most serious type of skin cancer, is diagnosed 17,500 times a year.
According to Cancer Research UK, one in 35 men and one in 41 women in the UK will now be diagnosed with melanoma skin cancer in their lifetime.
GP Dr Philippa Kaye told Sun Health: 'It's important to know your body and become familiar with your moles and skin and what they look like, so you will recognise if something changes,'
'See a doctor if you notice a mole is changing, which can be in colour, size, appearance but also in sensation - so if a mole is bleeding, crusty or becomes sore or itchy.'
Your GP will likely use the ABCDE mnemonic to help tell if a mole is cancerous or not, and you can use it at home too.
Get a loved one to help you check your WHOLE body - including the bits you can't see - and don't forget to return the favour!
Asymmetrical – melanomas usually have two very different halves and are an irregular shape
Border – melanomas usually have a notched or ragged border
Colours – melanomas will usually be a mix of two or more colours
Diameter – most melanomas are usually larger than 6mm in diameter
Enlargement or elevation – a mole that changes size over time is more likely to be a melanoma
What your hands can reveal about your health
Your hands can tell you a lot about the state of your health.
From what a weak handshake means for your ticker, to how the length of your fingers may indicate a cancer risk, they are able to reveal quite a bit.
GP Dr Sarah Garsed says: 'We often start with the hands for examinations when patients come to us.
"We can tell huge amounts from them, so any change to your hands that is prolonged, we recommend you get it checked by your GP.'
Here we look at everything you should be on the lookout for:
1. Enlarged fingertips
Sudden growth in your fingertips could be a reason to seek advice on your respiratory health.
Dr Garsed says: 'This symptom is basically an increase in the tissue around the ends of the fingers.
'This is not something you should ignore as it can be a sign that you have low oxygen in your blood.
'Low oxygen in the blood is always a red flag as it can indicate early signs of lung disease and is something that can be checked with a simple blood test by your GP.'
2. Weak grip
A weak handshake has long had associations with nervousness or being a bit of a wimp – but it could signal something much more significant.
In fact, a feeble grip has been linked to a shorter life expectancy and a higher risk of cognative decline and dementia.
A nationwide study published in the British Medical Journal found that those who develop a weak hold in midlife have a 20 per cent higher risk of death from heart and respiratory diseases and cancer.
3. Long index fingers
The length of your fingers can give indications about your health – especially if you are male.
A study by the International Journal of Medical Sciences found that if an index finger is much longer than the ring finger, it can be a sign of coronary artery disease.
However, men whose index fingers are the same length or longer than their ring fingers are 33 per cent less likely to be diagnosed with prostate cancer, according to a 2010 study published in the British Journal of Cancer.
4. Red, white or blue fingers
Fingers that turn white, red or blue can suggest poor circulation.
Often a change in temperature from hot to cold, or exposure to long periods of chilly temperatures, causes the colour change, but extreme stress or trauma can also bring it on.
Dr Garsed says: 'Regular bouts of extreme colour change in the fingers show your circulation is not functioning correctly and is usually a sign of Raynaud's disease.
'A lack of adequate blood supply is what causes the fingers to go white or blue, while a sudden return of circulation of blood to the area is what causes redness and swelling."
5. Little red rash
Small red bumps or blisters on your hands or wrists can point towards a food allergy.
Sensitivity to nickel – traces of which are found in foods including beans and legumes, chocolate, peanuts, soy, oatmeal and granola – is a common allergy. If you experience any persistent rashes on your hands, it could be a sign.
Dr Garsed says: 'You can easily find out if you do have the allergy by simply cutting out foods with nickel in them and seeing if your rash disappears.'
6. Finger clubbing
You might think signs of lung cancer - one of the most common and serious types of the disease - would only show up in your breathing.
But a less common sign of the disease can affect your fingers - and a simple test you can perform at home could reveal if you are at risk of lung cancer.
All you need to do is take the 'diamond gap' finger test, also known as the Schamroth window test.
This involves placing your nails together to see if there's a diamond-shaped space between your cuticles.
If there isn't a space, this is a sign of what's called finger clubbing, when the tips of your fingers become rounded and bulbous.
According to the Roy Castle Lung Cancer Foundation, about 35 per cent of people who have non-small cell lung cancer have finger clubbing and 4 per cent of those with small cell lung cancer.
Non-small cell is the most common form of the disease and makes up about 85 per cent of cases, NHS guidance said. Small cell is the less common variety which spreads faster.
Finger clubbing happens in stages and can take years to develop, according to Cancer Research UK. It usually affect the fingers on both your hands, but you might see it on your toes too.