Dr Helen Rippon, Head of Research Management at the Prostate Cancer Charity, said:

"Being able to identify early and with confidence men who are at risk from a high grade, potentially life threatening prostate tumour from those who are likely to develop a slow growing form of the disease is one of the most important questions facing prostate cancer research today. This new study is one of the first to investigate if there is a possible link between male infertility and the risk of developing an aggressive prostate cancer.

"The findings of this research offer little practical advice to men wishing to reduce their risk of the disease. The reported link between male infertility and a raised risk of higher grade prostate cancer is based on a very small number of men. Only 19 of the 4,500 men who took part in the study were diagnosed with high grade prostate cancer and just 16 men were diagnosed with the form of the disease in the control group. With such small numbers of men affected, it is difficult to draw any firm conclusions about whether the suggested link does exist.

"This potential new risk factor would need to be backed up by further, large scale studies before any recommendations can be made about targeting early screening for prostate cancer at men with fertility problems."