Men whose index fingers are longer than their ring fingers are much less likely to develop prostate cancer, a new study suggests.
The association is so strong that researchers believe the simple test could be part of a screening process for the disease.
The study led by The University of Warwick and The Institute of Cancer Research (ICR) found men whose index finger is longer than their ring finger were one third less likely to develop the disease in their lifetime than men with the opposite finger lengths.
When it comes to the risk of developing the disease before they are 60 the link was even greater with longer index fingered men having 87 per cent less chance.
“Our results show that relative finger length could be used as a simple test for prostate cancer risk, particularly in men aged under 60,” said the joint author Professor Ros Eeles from the ICR and The Royal Marsden NHS Foundation Trust.
“This exciting finding means that finger pattern could potentially be used to select at-risk men for ongoing screening, perhaps in combination with other factors such as family history or genetic testing.”
For a 15 year period from 1994 to 2009, the researchers quizzed more than 1,500 prostate cancer patients along with more than 3,000 healthy cases.
The men were shown a series of pictures of different finger length patterns and asked to identify the one most similar to their own right hand.
The most common finger length pattern, seen in more than half the men in the study, was a shorter index than ring finger.
Men whose index and ring fingers were the same length (about 19 per cent) had a similar prostate cancer risk, but men whose index fingers were longer than their ring finger were 33 per cent less likely to have prostate cancer, a disease which kills 10,000 people a year in Britain.
Risk reduction was even greater in men aged under 60 years– these men were 87 per cent less likely to be in the prostate cancer group.
The relative length of index and ring fingers is set before birth, and is thought to relate to the levels of the sex hormone testosterone the baby is exposed to in the womb.
Less testosterone equates to a longer index finger, the researchers now believe that being exposed to less testosterone before birth helps protect against prostate cancer later in life.
Previous studies have found a link between exposure to hormones while in the womb and the development of other diseases, including breast cancer (linked to higher prenatal oestrogen exposure) and osteoarthritis (linked to having an index finger shorter than ring finger).
Testosterone is known to be a driver of prostate disease once it has taken hold but this suggests it is also a major cause.
Professor Ken Muir, co-author from the University of Warwick, said: “Our study indicates it is the hormone levels that babies are exposed to in the womb that can have an effect decades later.
“As our research continues, we will be able to look at a further range of factors that may be involved in the make-up of the disease.”
Emma Halls, Chief Executive of Prostate Action, which helped fund the work published in the British Journal of Cancer, said: “This research brings us another step closer to helping determine risk factors for prostate cancer, which is possibly the biggest issue in current thinking about preventing and treating the disease.
“However, we are still a long way from reducing the number of men who die of prostate cancer every year and need more research and education in all areas to achieve this.”