Early PSA Screening Reduces Metastatic Prostate Cancer Risk

By Jeff Minerd , MedPage Today Staff Writer - Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.

Source News Article: Bloomberg, USA Today, Washington Post (Registration Req.)
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Advise asymptomatic men age 40 or older of the potential risks and benefits of PSA screening.

Advise patients who inquire that several large clinical trials are underway that will provide more definitive evidence about the effectiveness of PSA screening to reduce morbidity and mortality, but these studies will take few years.



Review TORONTO, July 8-Screening asymptomatic men with PSA reduced their risk of developing metastatic prostate cancer by 35%, researchers reported here.

The finding emerged from a population-based case control study in the Greater Toronto Area of 236 men ages 40 or older with advanced metastatic prostate cancer and a matched control group of 462 men who did not have metastatic prostate cancer.

The researchers obtained a history of PSA testing, digital rectal examination, symptoms, and other health data from medical records and a self-administered questionnaire, Vivek Goel, M.D., of the University of Toronto and colleagues reported in a study published online today by the Journal of Urology.

Statistical analysis showed that the frequency of PSA screening was significantly lower among the men with metastatic cancer than among the controls (odds ratio 0.65, 95% confidence interval 0.47-0.90). From this finding, the researchers concluded that PSA screening reduced the risk of metastatic prostate cancer by 35%.

"Our study provides suggestive evidence for the effectiveness of screening with PSA as actually practiced in the study area in the 1990s and early 2000s," the researchers concluded. "It is possible that a greater benefit would result from a screening program with regular screening intervals."

Although the study did not include mortality from prostate cancer as an endpoint, "those two outcomes -- mortality and metastasis -- are to some extent equivalent because metastatic prostate cancer is not curable and is associated with a poor prognosis," said Jacek A. Kopec, M.D., Ph.D., of the University of British Columbia, a co-investigator.

"There are many arguments both for and against the efficacy of this form of early screening," said Dr. Goel. "Our study shows a fairly significant benefit, and this benefit is demonstrated even among men who were not screened regularly as part of a screening program."

Several large, clinical trials already underway will provide more definitive evidence about whether PSA screening actually reduces morbidity and mortality from prostate cancer, the researchers noted, but the results of these trials are several years away.

Another controversy about PSA screening involves finding the best PSA cut off level for recommending a biopsy. The current standard, 4ng/ml, yields a false positive rate of only 6.2%, but misses nearly 80% of all prostate malignancies, according to a study published in the July 6 issue of the Journal of the American Medical Association.

Lowering the cut off to 1.1ng/ml would detect more than 80% of tumors, but also result in a false positive rate of more than 60%, the study found.

Related article:
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Standard PSA Cut-off Said to Miss Most Prostate Cancer

Primary source: The Journal of Urology - Source reference:
Kopec JA et al. Screening with prostate specific antigen and metastatic prostate cancer risk: a population based case-control study. The Journal of Urology. Advanced online publication July 8, 2005.



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