Men with Low PSA Levels May have Prostate Cancer

In the first systemic study of men with prostate-specific antigen (PSA) levels from 0-4 ng/ml, results showed that prostate cancer can be present in men with "normal” PSA levels. The findings were reported in the May 27, 2004, issue of The New England Journal of Medicine.

The study involved 2,950 men from the control arm of the Prostate Cancer Prevention Trial (PCPT) who were given a placebo instead of a drug called finasteride and received annual prostate screening for seven years with a PSA test and a digital rectal exam (DRE). All were 55 or over and had an initial PSA level of 3 ng/ml or less and a normal DRE. The study found that 15% had a positive biopsy despite having such low PSA levels. However, only 2.3% of men with PSA levels of 4 ng/ml or less had high-grade cancers. Gleason scores of the highest grades, 8-9 ng/ml, were found in only seven participants. Most of the men with prostate cancer (349, or 78%) had Gleason scores of 5-6 ng/ml.

"Most of these men would not have been diagnosed if they had not taken part in this study, since biopsies are not routinely performed in men with such low PSA levels,” said Leslie Ford, associate director for clinical research in the National Cancer Institute's Division of Cancer Prevention (www.nci.nih.gov), who participated in the research.

On the other hand, if the PSA threshold for proceeding to prostate biopsy was increased, there would be a risk of overdiagnosing and overtreating clinically unimportant disease, pointed out study leader Ian Thomson, M.D., of the University of Texas Health Science Center (San Antonio, USA). For this reason, PSA testing is not a universally recommended screening procedure. Also, other studies have shown that complexed PSA (cPSA) is more accurate.




Related Links:
NCI
U. Texas Health Science Center