A number of experts have revealed a simple finger test that can show if a person is at risk of lung cancer. This test, called the "diamond gap" or "Shamrath window" test, takes only five seconds to detect digital clubbing, which is an indicator of lung cancer. To perform this test, simply place the nails of your index fingers together, back to back, to see if there is a diamond-shaped gap between them. If there is no space and the nail beds are touching, this indicates digital clubbing. This may mean fluid accumulation around the lungs, which is a significant sign of lung cancer, the deadliest type of cancer in the United States.
Digital clubbing occurs when soft tissues at the tips of the fingers swell, causing the nails to change shape. The exact mechanisms are unclear, although experts believe it may be due to excessive production of Vascular Endothelial Growth Factor (VEGF), a protein that signals blood vessels to grow. This results in increased blood flow to areas like the fingers, as well as fluid accumulation throughout the body, known as edema and inflammation.
Digital clubbing is believed to be more common in non-small cell lung cancer (NSCLC), the most common form of lung cancer, affecting about 35% of patients. However, not seeing this diamond gap does not automatically mean that you have cancer, as digital clubbing has been observed in conditions such as celiac disease, ulcerative colitis, and thyroid problems.
