The recent results from the PCPT represent a milestone in cancer research, showing that prostate cancer could be prevented through chemoprevention. The study found the commonly used drug finasteride reduced the incidence of prostate cancer by 24.8 percent compared to a 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 7 years of PCPT.
To explore the problem, Joseph M. Unger, M.S. and a team of researchers from the Southwest Oncology Group Statistical Center at the Fred Hutchinson Cancer Research Center in Seattle, WA analyzed Surveillance, Epidemiology, and End Results (SEER) registry data and applied the results from the PCPT.
The results showed a net reduction in person-years saved over ten years using finasteride even after taking into account an increase in high-grade cancers. Using PCPT's 24.8 percent reduction in new cases, the drug would save 316,760 person-years over ten years. An absolute increase in 6.9 percent 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 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."
Article: "Estimated Impact of the Prostate Cancer Prevention Trial on Population Mortality," Joseph M. Unger, Ian M. Thompson, Jr., Michael LeBlanc, John J. Crowley, Phyllis J. Goodman, Leslie G. Ford, Charles A. Coltman, Jr., CANCER; Published Online: February 28, 2004 (DOI: 10.1002/cncr.20919); Print Issue Date: April 1, 2005.
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Cancer