A study from the University of Nottingham suggests that patients with an index finger longer than their ring finger have approximately two-thirds the risk of prostate cancer of those with equal finger lengths or longer ring fingers. The hypothesis is that the ratio of 2nd and 4th digit (index and ring fingers, 2D and 4D) length is fixed in utero and is altered by exposure to sex hormones at that time. The 2D:4D ratio is negatively correlated with testosterone exposure and positively related to oestrogen concentrations. This ratio may therefore act as a proxy indicator for prenatal testosterone levels. 'The study suggests that patients with an index finger longer than their ring finger have approximately two-thirds the risk of prostate cancer of those with equal finger lengths or longer ring fingers. Clearly, before you start studying your right hand, or that of your partner/father/friends etc, it should be remembered that this study has many limitations. It is a relatively small case-control study, relying on subjective self-collected data.'However, the findings are consistent with those of a paper in the British Journal of Urology,1 where those with a lower digit ratio (i.e. index finger shorter than ring finger) had higher mean PSA levels, higher risk of prostate biopsy and subsequent diagnosis of prostate cancer.