BACKGROUND: The ratio of the second to the fourth digit (2D:4D ratio) is a 
sexually dimorphic trait established in utero that differs between ethnic 
groups. It is associated with prenatal androgen exposure, and studies have 
evaluated the ratio as a marker for certain traits and disease states known to 
be associated with higher levels of in utero androgens, such as prostate cancer. 
There are currently no screening tools that stratify men with prostate cancer 
according to the severity of their disease. This study aims to investigate the 
2D:4D ratio as a potential marker for prostate cancer severity. Our hypothesis 
was that lower digit ratios, representing higher in utero androgen exposure, 
would be associated with more severe disease.
METHODS: Measurements were taken of the second and fourth digits of the right 
hand of male patients diagnosed with prostate cancer. Gleason score, presence of 
metastasis, family history, age at diagnosis and race were recorded. The 
distribution of demographic and other patient characteristics were compared with 
digit ratios to determine relationships.
RESULTS: African-American men with prostate cancer are 3.70 times more likely to 
have a low 2D:4D digit ratio than Caucasian men with prostate cancer (95% 
confidence interval: 1.98, 6.92; P < 0.0001). There were no statistically 
significant differences in the presence of metastasis, Gleason score, family 
history or age at diagnosis by digit ratio.
CONCLUSION: 2D:4D ratio shows strong differences between African-Americans and 
Caucasians; however, it does not correlate with disease severity in men already 
diagnosed with prostate cancer. Although this is a small population sample with 
possible confounding factors, it does not provide evidence to support the 
hypothesis that prenatal androgens affect prostate cancer grade or progression.