A drug with mixed results in preventing prostate cancer in clinical trials costs too much for daily, long-term use, according to a new analysis by Public Health Sciences Division researchers. The study estimates that prescribing finasteride, a medication used to treat prostate-gland enlargement, for all men above age 55 would cost $1.6 million to gain one additional year of life.
The findings are part of a follow-up analysis of the Southwest Oncology Group's Prostate Cancer Prevention Trial (PCPT), a randomized, seven-year clinical trial of more than 18,000 healthy middle-aged and older men. Two years ago, PCPT reported a nearly 25 percent reduction in prostate cancer among men who took finasteride. That study also showed an increase in the rate of more lethal high-grade prostate cancers.
In the new study, which is based on a mathematical model to determine finasteride's cost-effectiveness as a preventive measure, the researchers predict that the cost and potential harm of the drug far outweigh the possible benefits.
The analysis is published in the August edition of the American Journal of Medicine. Dr. Steve Zeliadt, a scientist with the Translational Outcomes Research program, led the study. The researchers found only men who lived beyond age 80 experienced fewer prostate-cancer deaths due to finasteride's prevention of low-grade prostate cancer. Considering the substantial cost of the medication, the survival benefit is small and only realized many years after initiating treatment, Zeliadt said.
"While preventing prostate cancer is desirable, there are large clinical and economic implications of using drug therapy as a prevention method where the gains take 30 years to be realized," Zeliadt said. "A high-grade tumor in prostate cancer is the only thing that distinguishes a 'good' and 'bad' cancer. Preventing low-grade prostate cancer is a good thing, but in order to lower prostate-cancer mortality, it is absolutely necessary to reduce the number of high-grade tumors."
There are mixed opinions about finasteride's potential. Another analysis of the PCPT findings earlier this year found that if finasteride were routinely prescribed for all men above age 55, it could save more than a quarter of a million lives in that cohort over the course of a decade. The two analyses looked at survival and incidence data differently to estimate the drug's projected impact. Zeliadt and colleagues believe the previous analysis overestimated the potential lives saved with finasteride by comparing older prostate-cancer patients with men in the general population. In the current analysis, the medication is associated with a gain of only six years of life per 1,000 men.
Dying with cancer, not from it
The researchers also looked at quality-adjusted life-years (QALYs), which take into account how disease impacts quality of life. The results showed 46 QALYs gained due to finasteride use per 1,000 men, primarily because of the drug's proven effectiveness in reducing the symptoms of prostate-gland enlargement and not due to prevention of cancer.
"For the average man with localized prostate cancer, the disease is very rarely a death sentence," said Dr. Scott Ramsey, a PHS researcher and one of the study's co-authors. "Most men die with their prostate cancer rather than from it. We'd like to prevent incidence of the type of cancer that's going to kill you, and that's a small fraction of all prostate cancers. This drug doesn't do that."
Drs. Ruth Etzioni and David Penson, also of the Hutchinson Center, and Dr. Ian Thompson, of the University of Texas Health Sciences Center, contributed to the analysis.