PSA test has higher accuracy for patients taking finasteride

Finasteride increases prostate-specific antigen (PSA) testing's ability to detect prostate cancer, a study in the August 16 Journal of the National Cancer Institute reports.

Finasteride is a drug prescribed for men whose prostates have become enlarged. The drug decreases prostate swelling and helps men with urinary problems. However, an increased number of high-grade tumors in men taking finasteride in the Prostate Cancer Prevention Trial (PCPT) has some physicians worried about the effect of the drug.

Ian M. Thompson, M.D., of the University of Texas Health Science Center in San Antonio, and colleagues examined the PSA test's ability to detect prostate cancer in the PCPT in men taking finasteride or a placebo. The group studied the PSA test's sensitivity and diagnostic accuracy for both groups.

The authors found that finasteride changed the diagnostic characteristics of the PSA test so that it detected prostate cancer with higher sensitivity and accuracy in men in the finasteride group than men in the placebo group. They suggest that the increased detection of high-grade prostate cancers in the finasteride arm of the PCPT may be related to the drug's ability to improve the PSA test's performance and not to it's induction of high-grade disease.

The authors write, "This bias would be expected to contribute to greater detection of all grades of prostate cancer with finasteride."

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