Routine Prostate Cancer Screening With PSA Test: Insufficient Evidence

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Main Category: Prostate / Prostate Cancer
Also Included In: Medical Devices / Diagnostics;  Cancer / Oncology
Article Date: 25 Sep 2009 - 0:00 PDT

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Two papers published on bmj.com today report that there is unsatisfactory evidence to support population-wide screening for prostate cancer using the prostate specific antigen (PSA) test.

The PSA test cannot differentiate lethal from harmless prostate cancer, according to the authors. This could lead to over diagnosis and overtreatment of healthy men.

Prostate specific antigen (PSA) is a protein formed in the cells of the prostate gland. It is present in small quantities in the blood of healthy men. It is frequently elevated in men with prostate cancer and in men with benign prostatic enlargement.

Although it remains controversial, PSA screening is commonly used in many countries. The latest study suggests that prostate cancer deaths were lower among screened men but at a cost of significant over diagnosis and treatment.

A Swedish team of researchers set out in the first study to evaluate how well prostate specific antigen predicted a potential prostate cancer diagnosis.

They used PSA test results from 540 men diagnosed with prostate cancer measured several years before diagnosis and from 1,034 healthy controls. Results indicated that the PSA test did not reach the probability ratios. It is a measure used to predict disease required for a screening test. Only very low concentrations of PSA (less than 1ng/ml) virtually ruled out a diagnosis of prostate cancer during monitoring.

The researchers inform that there is a need for other biomarkers for early detection of prostate cancer and before population based screening for prostate cancer should be introduced.

US researchers looked at the benefits and risks of PSA screening in a second analysis paper. They concluded that data on costs and benefits remain insufficient to support population based screening. In addition, they recommend further accurate measuring of the financial and psychological costs of false positive results, over diagnosis and overtreatment of prostate cancer.

In conclusion, they consider that men should be entirely informed of the benefits, harms and uncertainties associated with the PSA test before they are screened.

This observation is supported in a complementary editorial by researchers at Monash University in Australia.

Dr Dragan Ilic and Professor Sally Green write: "Clinicians and patients are faced with many uncertainties when considering whether or not to undergo prostate screening."

They remark: "Further research is required to develop and evaluate a valid screening test for prostate cancer." Until such a test exists, the choice to undertake screening should follow a shared decision making approach.

"Prostate specific antigen for early detection of prostate cancer: longitudinal study"
Benny Holmstro¨m, urologist, Mattias Johansson, postdoctoral fellow, Anders Bergh, professor of pathology, Ulf-Ha°kan Stenman, professor of clinical chemistry, Go¨ran Hallmans, professor of nutritional research, Pa¨r Stattin, professor of urology
BMJ 2009;339:b3537
doi:10.1136/bmj.b3537

"Screening for prostate cancer remains controversial"
Jennifer R Stark postdoctoral fellow of epidemiology, Lorelei Mucci assistant professor of epidemiology, Kenneth J Rothman professor of epidemiology and medicine, Hans-Olov Adami professor of epidemiology
BMJ 2009; 339:b3601

"Prostate specific antigen for detecting early prostate cancer"
Dragan Ilic senior lecturer, Sally Green professorial fellow
BMJ 2009; 339:b3572
bmj.com

Written by Stephanie Brunner (B.A.)
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