What is the primary advantage of combining a 5‑alpha‑reductase inhibitor with an alpha‑blocker in the management of benign prostatic hyperplasia?

Combination Therapy (5-ARI + Alpha Blocker) in BPH Management

The primary advantage of combination therapy with a 5-alpha-reductase inhibitor and an alpha-blocker is a 67% reduction in overall disease progression, a 79% reduction in acute urinary retention, and a 67% reduction in the need for BPH-related surgery compared to alpha-blocker monotherapy. 1

Disease-Modifying Benefits: The Core Advantage

The correct answer is B. Reduction in relative risk of disease progression and urinary retention.

Combination therapy uniquely prevents long-term complications rather than merely treating symptoms. The landmark MTOPS trial demonstrated sustained benefits over 5 years, with only treatment arms containing a 5-ARI showing significant reductions in acute urinary retention and need for invasive therapy. 1, 2

Specific Risk Reductions

• Acute urinary retention: 79% reduction versus alpha-blocker alone 1
• BPH-related surgery: 67% reduction versus alpha-blocker alone 1
• Overall clinical progression: 67% reduction compared to monotherapy 3
• The FDA label confirms finasteride combined with an alpha-blocker reduces the risk of symptomatic progression (≥4 point increase in AUA symptom score) 4

Why the Other Options Are Incorrect

Option A: "Immediate cure of BPH" is False

• BPH is a chronic progressive condition requiring indefinite therapy, not a curable disease 3
• The 5-ARI component takes 3-6 months to show benefit, with maximum effect at 6-12 months—nothing immediate about it 1
• Combination therapy manages and prevents progression but does not cure the underlying prostatic enlargement 1

Option C: "Elimination of need for PSA monitoring" is False

• The opposite is true: 5-ARIs reduce PSA by approximately 50% after 1 year, requiring clinicians to double the measured PSA value for accurate prostate cancer screening 1
• Failing to adjust PSA interpretation leads to delayed cancer diagnosis—a critical pitfall 1
• PSA monitoring becomes more complex, not eliminated 5

Option D: "Prevention of all prostate cancers" is False

• The FDA explicitly states finasteride is not approved for the prevention of prostate cancer 4
• The PCPT trial actually showed a controversial finding of higher-grade cancers (Gleason 8-10) in finasteride-treated men (1.8% vs 1.1% placebo), though this may reflect delayed diagnosis rather than true increased risk 1
• 5-ARIs have no role in cancer prevention as part of BPH management 4

Patient Selection for Maximum Benefit

Combination therapy provides the greatest absolute risk reduction in men with:

• Prostate volume >30 cc (ideally >40 cc) 1
• PSA >1.5-2.0 ng/mL 3
• Moderate-to-severe symptoms (IPSS >8) 5

These patients have higher baseline risk of progression and derive the most substantial benefit from disease modification. 1, 6

Critical Clinical Context

The primary value of adding a 5-ARI to an alpha-blocker is disease modification and prevention of long-term complications, not symptom relief. 3 While alpha-blockers provide rapid symptom improvement within 3-5 days, the 5-ARI component prevents the natural history of BPH progression—acute retention and surgery—over years of follow-up. 1

Long-term Korean cohort data spanning 10 years confirmed combination therapy reduced AUR incidence to 2.8% versus 13.6% with alpha-blocker monotherapy (p<0.001), with benefits most pronounced in men with PSA >2.0 ng/mL or prostate volume >35 mL. 6