BERKELEY, CA (UroToday Inc.) - Serum prostate specific antigen (PSA) and digital rectal examination are considered the standard of care for the screening of prostate cancer. Early studies showed that proportionally elevated PSA levels reflected higher clinical stages of prostate cancer. However more recent studies have questioned the nature of the relationship between serum PSA and prostate cancer.

Dr. Thomas Stamey and colleagues from the Department of Urology at Stanford University in Northern California reviewed their 20 year experience with serum PSA and prostate cancer to shed some light on this controversial subject. Their findings were published in the October 2004 edition of the Journal of Urology.

They reviewed 1317 prostate specimens from untreated radical prostatectomies, from surgery performed at Stanford U. from 1983 to 2003. One pathologist examined these specimens with 3 mm step sections. Pathologic information obtained included largest cancer volume and percent Gleason grade 4/5 of the largest cancer. They further evaluated for capsular penetration, positive lymph nodes, seminal vesicle invasion and total prostate weight. Preoperative clinical staging including PSA was recorded. The specimens were divided into 5-year time intervals, and using a variety of statistical analyses, selected variables were compared.

During the fist 5- year period (August 1983-December 1988), they found that preoperative serum PSA had a strong Pearson correlation to the volume of largest cancer, capsular penetration, positive lymph nodes, percentage of seminal vesicle invasion, percentage of Gleason grade 4/5 and prostate weight. It was more weakly correlated with clinical stage, and there was no correlation with age. This contrasted with the most recent 5-year period (January 1999-July 2003), when only prostate weight had a significant correlation to preoperative serum PSA levels. As the authors state, "this finding suggests that PSA today as a basis for diagnosing and treating prostate cancer is related only to the amount of benign prostatic hyperplasia in the prostate."

In conclusion, current serum PSA appears to be more related to benign prostatic hyperplasia than to prostate cancer. This may be due to increased prostate cancer screening and prostate biopsies that were performed in the early PSA era. PSA, however, remains a useful marker for follow-up after radical prostatectomy for cancer.

J Urol 2004; 172:1297-1301