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Table 1 Comparison of the two randomized controlled trials of 5-α reductase inhibitors for primary prevention of prostate cancera

From: 5-α reductase inhibitors and prostate cancer prevention: where do we turn now?

  PCPT REDUCE
Agent studied Finasteride 5 mg Dutasteride 0.5 mg
Manufacturer Merck & Co., Inc. GlaxoSmithKline
Enzyme inhibition 5-AR type 2 5-AR types 1 and 2
Study size 18,882 8,231
Final analysis size, (drug:placebo) 9,060 (4,368:4,692) 6,729 (3,305:3,424)
Follow-up 7 years 4 years
Eligibility criteria Age ≥55 years Age 50 to 75
  Normal DRE PSA 2.5 to 10 ng/mL
  PSA ≤3 ng/mL Prior negative prostate biopsy (6-core minimum) within 6 months
  AUA Symptom Score <20 AUA Symptom Score <25 (or <20 if taking α blockers)
   Excluded if
      HGPIN
      ASAP
      > 1 biopsy prior
      Gland volume > 80 cm3
In-study measures Annual PSA, DRE Semiannual PSA, DRE
  Finasteride PSA adjusted by 2× to 2.3× Dutasteride PSA adjusted by 2×
  Triggers for biopsy Triggers for biopsy
     Abnormal DRE    Not specified
     PSA > 4 ng/mL Protocol biopsies at 2 and 4 years
  End-of-study biopsy offered to all without cancer after 7 years  
Biopsies for cause, % 39.4% 12.0%
Primary end point Prostate cancer detection Prostate cancer detection
     Finasteride 803 (18.4%)    Dutasteride 659 (19.9%)
     Placebo 1,147 (24.4%)    Placebo 858 (25.1%)
  RRR = 24.8%, 95% CI 18.6 to 30.6; P < 0.001 RRR = 22.8%, 95% CI 15.2 to 29.8, P < 0.001
Secondary end points Prostate volume at biopsy Change in prostate volume from years 1 to 4
     Finasteride = 25.5 cm3    Dutasteride 45.7 to 39.0 cm3 = -17.5%
     Placebo = 33.6 cm3    Placebo 45.8 to 56.2 cm3 = +19.7%
     Relative difference = 24.1%    Relative difference in final volume = 30.1%
   HGPIN
      Dutasteride 3.7%
      Placebo 6.0%
      RRR = 39.2%, 95% CI 24.2-51.1, p<0.001
   ASAP
      Dutasteride 3.8%
      Placebo 4.9%
      RRR = 21.2%, 95% CI 1.3-37.1, p = 0.04
High-grade disease Gleason ≥7 detection Gleason ≥7 detection
     Finasteride 280 (6.4%)    Dutasteride 220 (6.7%)
     Placebo 237 (5.1%)    Placebo 233 (6.8%)
     RR = 1.67, 95% CI 1.44-1.93, p = 0.005    RR = 1.02, p = 0.81
  Gleason ≥8 detection Gleason ≥8 detection
     Finasteride 90 (2.1%)    Dutasteride 29 (0.9%)
     Placebo 53 (1.1%)    Placebo 19 (0.6%)
     RR = 1.90; 95% CI and P value not given    RR = 1.5, 95% CI not given, P = 0.15
NNT to prevent 1 cancer 17 20
  1. a5-AR: 5-α reductase enzyme; 5-ARIs: 5-α reductase inhibitors; ASAP: atypical small acinar proliferation; AUA: American Urological Association; DRE: digital rectal examination; HGPIN: high-grade prostatic intraepithelial neoplasia; NNT: number needed to treat; RR: relative risk; RRR: relative risk reduction; 95% CI: 95% confidence interval.