Metastatic prostate cancer deaths unchanged over past 25 years

PSA screening has likely played an important role in the 40%-plus drop in prostate cancer mortality since the late 1980s, although the mortality rate for metastatic disease has remained the same, say study authors from the University of California, Davis.

The authors, who published their findings online in Cancer (Nov. 20, 2013), looked at survival for men initially diagnosed with metastatic cancer, hypothesizing that success in treating advanced cancer and improvements in mortality for metastatic disease could be driving observed changes in overall survival, independent of PSA testing. However, the authors found that over the past 25 years, mortality for men with advanced, metastatic prostate cancer has been mostly unchanged.

"Our research found that while the death rate from prostate cancer overall has declined, men whose cancer has spread beyond the prostate are still dying at the same rate as before. This finding suggests that routine PSA testing, which has dramatically reduced the incidence of metastatic disease, may be effective in reducing mortality from the disease, as well,” said senior author Marc Dall’Era, MD.

The authors examined data from the California Cancer Registry. They looked at men 45 years of age or older who first presented with metastatic prostate cancer between 1988 and 2009 and at overall survival for 19,336 men, stratifying the groups by time of diagnosis (including before and after PSA introduction), ethnicity, age, cancer grade, and other factors.

The research corroborates previous studies that had shown a 65% reduction in those initially diagnosed with metastatic cancer since the PSA test’s introduction. This reduction resulted from men being diagnosed at earlier stages after PSA screening. However, the current study shows that for those who were diagnosed with metastatic prostate tumors, survival has not improved.

“The effect we’re seeing on mortality in this group is more that we’ve shifted the stage of diagnosis much earlier,” Dr. Dall’Era said. “In other words, because the PSA test detects cancer earlier, fewer men go on to be diagnosed with metastatic disease. However, there has been no survival improvement for men with metastatic disease to account for the overall mortality decline among all men with prostate cancer.”

Although the study did not find any survival gains in men with advanced cancer, there is some good news. For example, the survival disparity between African-American and Caucasian men has declined over time. The findings show that both groups had similar survival rates following the introduction of the PSA test. In fact, the authors found that socioeconomic status is much more significant than race in determining survival.

Ultimately, the study failed to identify a potentially significant contributor to the decline in prostate cancer mortality. The authors said additional research is needed to determine what is causing these gains, including a renewed focus on the PSA test’s role in preventing mortality.

“These data suggest that we should continue to evaluate the benefits of PSA screening before making sweeping policy recommendations against its use,” said Dr. Dall’Era.

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