How easy ‘diamond gap’ test can reveal if you’re at risk of deadly lung cancer

YOU may think signs of lung cancer—one of the most common and serious types of the disease—show up only in your breathing.

Although people experience symptoms such as a persistent cough or shortness of breath, these usually do not appear until the cancer is in a later stage.

The Diamond Gap fingernail test can indicate if you suffer from finger strikes


The Diamond Gap fingernail test can indicate if you suffer from finger strikes
Finger smacks will cause the nails to curve more than usual - the change may be gradual


Finger smacks will cause the nails to curve more than usual – the change may be gradualPhoto credit: Kennedy News and Media
They could be a sign of a disease like lung cancer


They could be a sign of a disease like lung cancerPhoto credit: Kennedy News and Media

But a less common sign of the disease can affect your fingers — and a simple test you can do at home could reveal if you’re at risk for lung cancer.

All you have to do is take the diamond gap finger test, also known as the Schamroth window test.

To do this, you need to bring your nails together to see if there is a diamond-shaped space between your cuticles.

If there is no space, this is a sign of what is known as finger clubbing, when the fingertips become rounded and bulbous.

According to the Roy Castle Lung Cancer Foundation, finger punches affect about 35 percent of people with non-small cell lung cancer and 4 percent of people with small cell lung cancer.

Non-small cell cells are the most common form of the disease, accounting for around 85 per cent of cases, NHS guidelines say. Small Cell is the less common variety that spreads faster.

According to Cancer Research UK, clubbing occurs in phases and can take years to develop. It usually affects the fingers on both hands, but you can also see it on your toes.

First, you may notice softening at the base of your nails and some redness around them.

Next, the angle between the nail bed and the skin just below your cuticle increases, causing your nail to curve more than usual.

Your nail will develop ridges along its length and begin to shine, as will the skin around it.

Then the edges of your fingers will look larger, giving a bulbous, “club-like” appearance.

Although it’s unclear what exactly causes this, experts believe it could be because cells called megakaryocytes – which are responsible for making platelets – get stuck in the blood vessels in your fingertips and lead to tissue growth.

Finger banging can be an indicator of a range of health conditions affecting the heart and lungs, according to Cancer Research UK.

Aside from lung cancer, this quirk in the appearance of your fingers can also develop if you have mesothelioma — a type of cancer that affects the lining of some of your organs — some thyroid problems, ulcerative colitis and Crohn’s disease.

However, it has been pointed out that not all people with these conditions experience finger punches.

How to perform the Diamond Gap test

First, put your hands up in front of you and touch the tips of your two index fingers together.

Then bring your nails to touch by bending the tips of your fingers towards each other.

If you can see a little diamond spacing between them (Shamroth’s window) then your nails aren’t clubbed.

Touch the nails of your index fingers together to perform the


Touch the nails of your index fingers together to perform the “Diamond Gap” test – a window between them indicates your fingers are not gappedCredit: The Sun

It’s worth noting that slapping fingers doesn’t necessarily mean you definitely have lung cancer — and there are many reasons your fingers can look like this.

But the official guide states: “Finger clubbing is uncommon. If you think you may have it and are concerned, talk to your doctor.

“They can examine you and find out if you have other symptoms.

“They can send you for tests if necessary, e.g. B. to a chest x-ray to check your lungs.”

Other lung cancer symptoms

Lung cancer doesn’t always cause symptoms in its early stages, so people may not know they have it until it spreads to the lungs or other parts of the body.

Cancer Research UK experts said there are nine that are most common in those diagnosed with the disease.

They are:

  1. have a cough most of the time
  2. a change in a cough you have had for a long time – it may sound different or be painful when you cough
  3. getting out of breath doing things you used to do without problems
  4. Coughing up mucus (sputum) with blood in it
  5. have chest or shoulder pain
  6. Chest infections that keep coming back or a chest infection that doesn’t get better
  7. lose appetite
  8. feeling tired all the time (fatigue)
  9. lose weight

Though it’s rare, the medical community said some types of lung cancer cells produce hormones that get into the bloodstream.

They explained that these hormones can cause symptoms that don’t appear to be related to lung cancer.

Doctors call this paraneoplastic syndrome, and symptoms can include:

  • Tingling or numbness in your fingers or toes
  • muscle weakness
  • drowsiness, weakness, dizziness and confusion
  • breast swelling in men
  • blood clot.

The medics also warned that there is a very rare type of lung cancer that can grow right at the top of the lungs, called a Pancoasr tumor.

Most people with this type of cancer experience severe shoulder pain or pain that runs down the arm.

If you are concerned about any of your symptoms, you should make an appointment to see your GP.

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In an emergency, always call 999 or go to the nearest emergency room.

Russell Falcon

Russell Falcon is a USTimesPost U.S. News Reporter based in London. His focus is on U.S. politics and the environment. He has covered climate change extensively, as well as healthcare and crime. Russell Falcon joined USTimesPost in 2023 from the Daily Express and previously worked for Chemist and Druggist and the Jewish Chronicle. He is a graduate of Cambridge University. Languages: English. You can get in touch with me by emailing

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