Thompson IM et al. (2006) Effect of finasteride on the sensitivity of PSA for detecting prostate cancer. J Natl Cancer Inst 98: 1128–1133

The results of the Prostate Cancer Prevention Trial (PCPT) revealed that patients receiving finasteride had a lower risk of developing prostate cancer, but a higher risk of high-grade cancer, compared with those on placebo. Thompson et al. investigated whether treatment with finasteride could have affected the diagnostic performance of the PSA test.

This study included all men in the finasteride and placebo groups who underwent prostate biopsy and PSA testing during the 7-year PCPT. The effects of finasteride on the sensitivity of and the area under the receiver-operating-characteristic curve (AUC) of PSA tests for detection of prostate cancer by biopsy were investigated. Sensitivity was defined as the proportion of patients with PSA levels exceeding a series of cutoff values.

The finasteride group included 4,579 men, 695 of whom were diagnosed with prostate cancer. Of these, 38.5% had a Gleason score of ≥7. The placebo group consisted of 5,112 men, 1,111 of whom were diagnosed with prostate cancer. Of these, 21.8% had a Gleason score of ≥7. For all outcomes, the AUC was greater for the finasteride group than for the placebo group. At all PSA cutoffs, the sensitivity of PSA was greater in the finasteride group than in the placebo group.

Finasteride seemed to enhance the sensitivity and AUC of PSA testing for detecting all grades of prostate cancer. The higher risk of high-grade prostate cancer in the PCPT was partly a result of increased sensitivity of PSA, rather than a result of the induction of disease by finasteride.