Do the benefits of finasteride outweigh the risks in the prostate cancer prevention trial?
OBJECTIVE
The Prostate Cancer Prevention Trial demonstrated that finasteride could reduce the incidence of prostate cancer by 25%. However, its use was also associated with an increased risk of high grade cancer resulting in uncertainty surrounding the net benefits of therapy.


METHODS
We used the Montreal Prostate Cancer Model, a validated Markov model of prostate cancer progression, to compare the forecasted survival in treated and untreated men. The conditions of the model were varied to reflect different assumptions about whether the cancer grade difference observed in the PCPT was real or a treatment associated artifact, and whether cancers detected on end of study biopsies were clinically significant.


RESULTS
For a hypothetical cohort of 1,000, 62-year-old men treated with finasteride, an increased survival of 140 life-years (0.14 years per individual) is forecasted if all diagnosed cancers are considered. If tumor grade differences are held to be artifactual, the forecasted benefits increase to 200 life-years. However, if the tumor grade difference is real and only clinically detected cancers are considered, estimated increased survival is only 20 life-years (0.02 years per individual).


CONCLUSIONS
The primary prevention of prostate cancer with finasteride looks promising. However, at the present time it should only be considered with caution until we have answered critical questions surrounding the difference in cancer grade observed in the PCPT and the clinical significance of cancers detected on protocol directed end of study biopsies.
Division of Clinical Epidemiology, Centre for the Analysis of Cost-Effective Care, The Montreal General Hospital, Montreal, Quebec, Canada. nbouchard@epimgh.mcgill.ca
Steven
S
Grover
Ilka
I
Lowensteyn
David
D
Hajek
John
J
Trachtenberg
Louis
L
Coupal
Sylvie
S
Marchand
D000368:Aged; D000369:Aged, 80 and over; D002986:Clinical Trials as Topic; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D018120:Finasteride / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D008962:Models, Theoretical; D011471:Prostatic Neoplasms / Q000517:prevention & control*; D018570:Risk Assessment; D013997:Time Factors
D004791:Enzyme Inhibitors; D018120:Finasteride