Background: The ratio of the lengths of index and ring fingers (2D:4D) is a marker of prenatal exposure to sex hormones, with low 2D:4D being indicative of high prenatal androgen action. Recent studies have reported a strong association between 2D:4D and risk of prostate cancer.
Methods: A total of 6258 men participating in the Melbourne Collaborative Cohort Study had 2D:4D assessed. Of these men, we identified 686 incident prostate cancer cases. Hazard ratios (HRs) and confidence intervals (CIs) were estimated for a standard deviation increase in 2D:4D.
Results: No association was observed between 2D:4D and prostate cancer risk overall (HRs 1.00; 95% CIs, 0.92-1.08 for right, 0.93-1.08 for left). We observed a weak inverse association between 2D:4D and risk of prostate cancer for age <60, however 95% CIs included unity for all observed ages.
Conclusion: Our results are not consistent with an association between 2D:4D and overall prostate cancer risk, but we cannot exclude a weak inverse association between 2D:4D and early onset prostate cancer risk.