1. What is PSA Doubling Time?

PSA doubling time (PSADT) is the time it takes for prostate-specific antigen (PSA) levels to double in blood. It's an important prognostic marker in prostate cancer management, helping assess disease aggressiveness and progression.

2. How Does the Calculator Work?

The calculator uses the PSA doubling time formula:

Where:

• \( dt \) — PSA doubling time (months)
• \( time \) — Time interval between PSA measurements (months)
• \( psa1 \) — Initial PSA measurement (ng/mL)
• \( psa2 \) — Follow-up PSA measurement (ng/mL)

Explanation: The formula calculates how quickly PSA levels are rising by determining the time needed for PSA to double at the current rate of increase.

3. Importance of PSA Doubling Time

Details: PSADT helps in prostate cancer risk stratification, guiding treatment decisions, and monitoring disease progression. Shorter doubling times (<3 months) typically indicate more aggressive disease.

4. Using the Calculator

Tips: Enter the time interval between PSA tests in months, both PSA values in ng/mL. Ensure all values are positive and psa2 is different from psa1.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal PSA doubling time?
A: In healthy men, PSA levels typically remain stable. In prostate cancer, PSADT <3 months indicates aggressive disease, while >12 months suggests indolent disease.

Q2: How many PSA measurements are needed?
A: While two measurements provide initial estimate, more measurements over time increase accuracy of doubling time calculation.

Q3: Does PSADT predict prostate cancer mortality?
A: Yes, shorter PSADT is associated with higher risk of prostate cancer-specific mortality.

Q4: What affects PSA doubling time accuracy?
A: Factors include PSA assay variability, prostate manipulation (biopsy, DRE), infections, and medications (5-ARIs).

Q5: Is PSADT used in active surveillance?
A: Yes, it's a key parameter in active surveillance protocols to identify when intervention may be needed.