Prostate specific antigen variation in patients without clinically evident prostate cancer

Area of Science:

• Urology
• Oncology
• Biostatistics

Background:

• Prostate specific antigen (PSA) is a key biomarker in prostate cancer screening.
• Understanding long-term individual variation in PSA levels is crucial for accurate interpretation in men without clinical or biopsy evidence of prostate cancer.

Purpose of the Study:

• To analyze long-term within-individual variation of serum PSA.
• To assess the impact of the number of PSA measurements and interval duration on PSA variability.

Main Methods:

• Studied 943 men from a prostate cancer screening program with 2-3 PSA measurements.
• Calculated PSA variability using coefficient of variation, ratio difference, and PSA velocity.
• Assessed the relationship between variability, measurement interval, and sample number.

Main Results:

• Mean PSA variability decreased from 18% with 2 measurements to 15.7% with 3 measurements.
• PSA velocity remained within normal limits for over 95% of participants.
• Individual PSA variability was not significantly correlated with the interval between measurements.

Conclusions:

• PSA velocity is a reliable indicator in men without clinically relevant prostate cancer.
• Individual PSA variability is reduced by a third PSA measurement, independent of measurement interval.
• Long-term PSA monitoring requires careful consideration of the number of samples obtained.