Doctors found that the risk increases if the ring finger on the right hand is significantly longer than the index finger next to the thumb.

But men whose ring fingers are only slightly longer, or are about the same length, are much less likely to get the disease.

The findings open up the possibility of screening men with longer fingers at an early age for signs of cancer.

In the study, blood tests showed that men with longer ring fingers on their right hand had higher levels of prostate specific antigen (PSA).

This chemical is sometimes found in high levels in blood when cancer is present. The right hand was studied because the difference between the length of its ring finger and index finger is often greater than on the left, as it is more sensitive to hormonal changes in the womb.

The results are the latest in a long line of studies linking finger length to men’s health, most of which highlight the benefits of a long ring finger.

These include reduced risk of heart disease, a better chance of exam success and increased fertility.

Last year a team of experts from the Medical Research Council’s Epidemiology Resource Unit at Southampton University even found that young men with longer ring fingers made better sprinters.

Provenge – which is designed to be used in men with advanced disease – is the first of its kind to be accepted by the Food and Drug Administration.

Each dose has to be individually tailored and it is an expensive treatment at $93,000 per patient.

It will add to, rather than replace, existing treatments, said experts.

Doctors have been working on therapies that prompt the immune system to fight tumours for decades.

Potential success stories include an experimental vaccine for melanoma which is in the late stages of development.

This latest therapy is made by collecting special blood cells from each patient that help the immune system recognise cancer as a threat.

These are then mixed with a protein found on most prostate cancer cells and a substance which kick-starts the immune response.