Published in the April 1, 2005 issue of CANCER, the new analysis of data from the prostate cancer prevention trial (PCPT) indicates that any possible increase in the incidence of higher-grade tumors would be more than offset by an overall reduction in the number of prostate cancer cases in the general population.
The recent results from PCPT represent a milestone in cancer research, showing that prostate cancer could be prevented through chemoprevention.
The study found the commonly used drug finasteride, the active ingredient in Merck’s Proscar, reduced the incidence of prostate cancer by 24.8% compared to placebo. However, a possible increase in the number of high-grade tumors in the trial prompted many to question whether any benefits of the drug would be offset by an increase in mortality related to the higher-grade tumors. No difference in mortality was seen during the seven years of PCPT.
The results showed a net improvement in person-years saved over 10 years using finasteride even after taking into account an increase in high-grade cancers. Using PCPT’s 24.8% reduction in new cases, the drug would save 316,760 person-years over 10 years. An absolute increase in 6.9% of cases with high-grade disease (the difference seen in the PCPT) would still mean 262,567 person-years saved.
Based on this model, the study authors conclude, “even if finasteride is found to potentiate the growth of high-grade tumors, this analysis shows that the potential detrimental effects of an increased rate of cases with high grade Gleason score would be substantially outweighed by a reduction in incidence.”