1. What is PSA Doubling Time?

PSA doubling time (DT) is the time it takes for the prostate-specific antigen (PSA) level to double in value. This calculation helps assess prostate cancer progression and aggressiveness, with shorter doubling times indicating more aggressive disease.

2. How Does the Calculator Work?

The calculator uses the Sloan Kettering formula:

Where:

• \( PSA_1 \) — Initial PSA value (ng/mL)
• \( PSA_2 \) — Current PSA value (ng/mL)
• \( t_1 \) — Time of initial PSA measurement (months)
• \( t_2 \) — Time of current PSA measurement (months)
• \( \ln \) — Natural logarithm

Explanation: The formula calculates the exponential growth rate of PSA and determines how long it would take to double at that rate.

3. Importance of PSA Doubling Time

Details: PSA DT is a significant prognostic factor in prostate cancer. Doubling times less than 3 months may indicate aggressive disease, while longer doubling times suggest more indolent cancer.

4. Using the Calculator

Tips: Enter PSA values in ng/mL and time points in months. Ensure the second PSA is higher than the first and the second time point is later than the first for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a clinically significant PSA doubling time?
A: Generally, DT <3 months suggests aggressive disease, 3-12 months intermediate, and >12 months indolent disease.

Q2: How many PSA values are needed for accurate calculation?
A: While two points can estimate DT, more measurements over time provide more reliable results.

Q3: Does PSA doubling time help decide between active surveillance and treatment?
A: Yes, shorter doubling times often prompt consideration of active treatment rather than surveillance.

Q4: Can PSA doubling time predict survival?
A: Yes, shorter doubling times correlate with worse prognosis and shorter survival times.

Q5: Are there limitations to this calculation?
A: Accuracy depends on consistent measurement conditions and may be affected by PSA variability.