OBJECTIVE: To investigate the relationships between the 2nd to 4th digit ratio 
(digit ratio) and prostate volume, prostate-specific antigen (PSA) level, and 
the presence of prostate cancer.
PATIENTS AND METHODS: Of the men that presented with lower urinary tract 
symptoms (LUTS) at a single tertiary academic center, 366 men aged 40 or older 
with a PSA level ≤ 40 ng/mL were prospectively enrolled. Right-hand 2nd and 4th 
digit lengths were measured prior to the PSA determinations and transrectal 
ultrasonography (TRUS). Prostate volumes were measured by TRUS without 
information about digit length. Patients with a PSA level ≥ 3 ng/mL underwent 
prostate biopsy.
RESULTS: No relationship was found between prostate volume and digit ratio 
[correlation coefficient (r) = -0.038, P = 0.466]. But, significant negative 
correlations were found between digit ratio and PSA (r = -0.140, P = 0.007). 
When the patients were divided into two groups (Group A: digit ratio < 0.95, n = 
184; Group B: digit ratio ≥ 0.95, n = 182), Group A had a higher mean PSA level 
than Group B (3.26 ± 5.54 ng/mL vs 1.89 ± 2.24 ng/mL, P = 0.002) and had 
significantly higher risks of prostate biopsy [odds ratio (OR) = 1.75, 95% CI = 
1.07-2.84] and prostate cancer (OR = 3.22, 95% CI = 1.33-7.78).
CONCLUSIONS: Patients with a lower digit ratio have higher risks of prostate 
biopsy and prostate cancer.