Second to fourth digit ratio: a predictor of prostate-specific antigen level and the presence of prostate cancer.

Abstract

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. 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. 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). Patients with a lower digit ratio have higher risks of prostate biopsy and prostate cancer.