Track PSA kinetics for prostate cancer monitoring.
PSADT = Time × ln(2) / ln(PSA₂/PSA₁). PSADT < 3 months indicates aggressive cancer with high metastatic risk. PSADT > 12 months is generally favorable. After radical treatment, a rising PSA (biochemical recurrence) triggers PSADT calculation to guide salvage therapy timing. PSA velocity > 0.75 ng/mL/year is also concerning.