Prostate-specific antigen doubling time in prostate cancer: a review of calculation methods and clinical implications.

Purpose of review: Prostate-specific antigen doubling time (PSADT) is a key prognostic marker in prostate cancer, especially in cases of biochemical recurrence. It guides risk stratification and therapeutic decisions, but its calculation varies significantly across institutions. This review addresses the clinical relevance of PSADT and the need for standardized methods.

Recent findings: Multiple models exist for PSADT calculation, including logarithmic regression, linear models, and nadir subtraction. Logarithmic regression best reflects PSA's exponential growth but requires at least three PSA values over time. Measurement variability - due to assay differences or sampling intervals - can affect PSADT estimates by 15-40%, impacting treatment decisions. Correction tools like the Memorial Sloan Kettering Cancer Center's Excel calculator have reduced variability by up to 30-40%, improving reliability.

Summary: PSADT remains a valuable tool in prostate cancer management, particularly for guiding salvage therapies in biochemical recurrence. However, its accuracy depends on the calculation method and PSA measurement quality. Integrating validated tools like the MSKCC calculator and adopting standardized approaches can enhance clinical decision-making. This review underscores the need for improved harmonization of PSADT methodology across guidelines and clinical settings.