1. What is PSA Doubling Time?

PSA doubling time (DT) is the time it takes for the PSA level to double in value. It's an important prognostic marker in prostate cancer management, with shorter doubling times associated with more aggressive disease.

2. How Does the Calculator Work?

The calculator uses the PSA doubling time equation:

Where:

• \( DT \) — Doubling time (months)
• \( T \) — Time interval between measurements (months)
• \( PSA_f \) — Final PSA level (ng/mL)
• \( PSA_i \) — Initial PSA level (ng/mL)
• \( \ln \) — Natural logarithm

Explanation: The equation calculates how quickly PSA levels are increasing, which correlates with tumor growth rate.

3. Importance of PSA Doubling Time

Details: PSA DT is used to assess prostate cancer aggressiveness, guide treatment decisions, and monitor disease progression. DT < 3 months may indicate need for active treatment.

4. Using the Calculator

Tips: Enter PSA values in ng/mL and time interval in months. All values must be positive, and PSAf must be different from PSAi.

5. Frequently Asked Questions (FAQ)

Q1: What is a concerning PSA doubling time?
A: DT < 3 months is associated with higher risk disease, while DT > 12 months may indicate indolent disease.

Q2: How many PSA values are needed for accurate DT?
A: While this calculator uses two points, clinical decisions typically use ≥3 PSA values over ≥6 months for reliability.

Q3: Does PSA DT predict survival?
A: Yes, shorter DT correlates with worse prostate cancer-specific survival, especially in recurrent disease.

Q4: What affects PSA DT accuracy?
A: PSA bounces after treatment, infections, or prostate manipulation can temporarily affect PSA levels.

Q5: Can this be used during active treatment?
A: No, DT is primarily for untreated or recurrent disease. Treatment effects complicate interpretation.