What is the prostate volume in Benign Prostatic Hyperplasia (BPH)?

From the Guidelines

Prostate volume in Benign Prostatic Hyperplasia (BPH) is typically considered significant when it exceeds 30cc, as this is the threshold at which 5-alpha reductase inhibitors (5-ARIs) become more effective in reducing prostate size and improving symptoms. According to the most recent guidelines, a minimum prostate volume of >30cc or PSA >1.5ng/mL is necessary for a reliable 5-ARI response, with larger glands showing more pronounced effects 1. The size of the prostate can vary widely in BPH, ranging from 25 to over 100 cubic centimeters, with normal prostate volume being about 20-30 cc.

Key points to consider in the management of BPH include:

• Prostate volume is a critical factor in determining the effectiveness of treatment, with larger prostates responding better to combination therapy with alpha-blockers and 5-ARIs 1.
• 5-ARIs, such as finasteride and dutasteride, can reduce prostate volume by 15-25% at six months, with a corresponding decrease in PSA levels 1.
• The reduction in prostate volume and PSA levels can lead to improved symptoms and a reduced risk of clinical progression, as seen in the REDUCE trial 1.
• Imaging studies, such as transrectal ultrasound, CT scan, or MRI, can be used to measure prostate volume and guide treatment decisions 1.

In terms of treatment, 5-ARIs are a viable option for men with enlarged prostates (>30cc) and PSA >1.5ng/mL, as they can reduce prostate volume and improve symptoms. However, it's essential to consider the slow onset of action of these medications and counsel patients on the potential for slower symptom improvement compared to alpha blockers 1. Ultimately, the choice of treatment will depend on individual patient factors, including prostate size, symptom severity, and PSA levels.

From the FDA Drug Label

In A Long-Term Efficacy and Safety Study, prostate volume was assessed yearly by magnetic resonance imaging (MRI) in a subset of patients. In patients treated with finasteride tablets who remained on therapy, prostate volume was reduced compared with both baseline and placebo throughout the 4-year study. Finasteride tablets decreased prostate volume by 17.9% (from 55.9 cc at baseline to 45.8 cc at 4 years) compared with an increase of 14.1% (from 51.3 cc to 58.5 cc) in the placebo group (p<0.001). The mean prostate volume as measured by transrectal ultrasound was 36.3 mL (±20.1 mL). Prostate volume was ≤20 mL in 16% of patients, ≥50 mL in 18% of patients and between 21 and 49 mL in 66% of patients Mean prostate volume at baseline ranged between 40 to 50 cc.

The prostate volume in Benign Prostatic Hyperplasia (BPH) is:

• Mean baseline volume: between 40 to 50 cc, with a specific mean of 55.9 cc in one study and 36.3 mL in another.
• Range of baseline volumes: ≤20 mL in 16% of patients, ≥50 mL in 18% of patients, and between 21 and 49 mL in 66% of patients. 2

From the Research

Prostate Volume in Benign Prostatic Hyperplasia (BPH)

• The prostate volume in BPH can be used to select treatment, but it is not reasonable to decide whether to treat a patient with LUTS on the basis of prostate size 3.
• 5α-reductase inhibitors can decrease the production of dihydrotestosterone within the prostate, which results in decreased prostate volume 4, 5.
• Prostatic volume and transitional zone volume were significantly decreased in 5alpha-reductase inhibitor groups 6.
• In patients with baseline total prostatic volume (TPV) greater than 35.5 cm3, the improvement of Qmax was more significant than that in patients with TPV less than 35.5 cm3 in finasteride group 6.

Factors Affecting Prostate Volume

• Age, prostate size, weight, prostate-specific antigen level, and severity of the symptoms are factors that depend on the specific approach used to treat BPH 4.
• The degree to which the patient is bothered is more important than symptom score in BPH management 3.
• Bother, not symptom score or objective measures such as postvoid residual urine and uroflowmetry, is what drives the decision-making process in BPH management 3.

Treatment Options

• 5-alpha reductase inhibitors (5-ARIs) effectively reduce the serum and intraprostatic concentration of DHT, causing an involution of prostate tissue 5.
• α(1)-adrenergic receptor (α(1)-AR) antagonists decrease LUTS and increase urinary flow rates in men with symptomatic BPH 4.
• Combination therapy of 5α-reductase inhibitor and α(1)-AR antagonist has been shown to improve clinical efficacy 4.