The PSA cancer-screening test alone probably cannot explain the recent decline in deaths from prostate cancer, according to investigators at the Fred Hutchinson Cancer Research Center and the National Cancer Institute.
In a paper to appear in tomorrow's Journal of the National Cancer Institute, lead researcher Dr. Ruth Etzioni, a biostatistician at the Hutchinson Center, concludes that while prostate-specific-antigen, or PSA, blood testing may have played a partial role in the declining prostate-cancer death rate observed since the early 1990s, it is likely not the only cause.
"Our results suggest that we should interpret the population trends with caution," says Etzioni, an associate member of the Center's Public Health Sciences Division. "The average man on the street should not read too much into the declining mortality numbers. What we're seeing is probably not all due to PSA testing. There are, most likely, other things going on." Other factors that may contribute to the drop include changing patterns of treatment and treatment-related deaths, or misclassification of cause of death.
Etzioni's paper is one of three in this week's issue of the JNCI to address the role of PSA testing in reducing the prostate-cancer death rate. The others are by Drs. Benjamin Hankey and Eric Feuer of the National Cancer Institute, who also collaborated with Etzioni on her paper.
Used widely in this country since 1988, the PSA test measures the amount of prostate-specific antigen in the blood. This enzyme, produced by the prostate gland, can signal the presence of cancer when the level is significantly elevated.
Until quite recently, prostate-cancer mortality had long been on the rise.
Between 1973 and 1991, for example, the age-adjusted death rate increased from
21 to 27 men per 100,000. However, in the early 1990s, the death rate started
heading south, dropping to 24 men per 100,000 between 1992 and 1996.
As the declining mortality rate dovetailed with the
Contact: Kristen Lidke Woodward
Fred Hutchinson Cancer Research Center