Overall survival rates have improved for men with prostate cancer following the introduction of prostate-specific antigen (PSA) screening, particularly for African Americans, a new study indicates. However, researchers could not conclude that PSA monitoring alone is responsible for the increased survival.
The findings emerged from a comparison of overall survival in three sequential phase 3 trials of 3,096 men with newly diagnosed metastatic prostate cancer who underwent androgen-deprivation therapy. Two of the trials took place before the introduction of PSA screening and one took place after. (The FDA approved the PSA test in 1986 for the monitoring of prostate cancer progression. In 1994, the agency granted approval for the use of the PSA test in conjunction with a digital rectal examination to test asymptomatic men for prostate cancer.)
Median overall survival was 30 months in pre-PSA-era trial #1, 33 months in pre-PSA-era trial #2, and 49 months in the post-PSA-era trial. Adjusting for risk factors, there was a 22% lower risk of death in the post-PSA trial than in pre-PSA trial #2.
“While not all of these welcome improvements can be attributed strictly to PSA testing, without a doubt it has played a role in extending many lives,” acknowledged lead investigator Ian M. Thompson, Jr., MD, in a statement issued by Elsevier Health Sciences, the publisher of The Journal of Urology, which carried Thompson’s team’s report. Thompson is the director of the Cancer Therapy and Research Center at the University of Texas Health Science Center at San Antonio.
The improvement in overall survival was greater in African American men, who had a median survival of 27 months in each of the pre-PSA trials, compared with 34 months for other men in pre-PSA trial #1 and 35 months for other men in pre-PSA trial #2. The racial differences disappeared in the post-PSA trial, with overall survival of 48 and 49 months in African Americans and non-African Americans, respectively.
With an evaluation of ZIP code summary information regarding income and education demonstrating no shift in socioeconomic status over time for African American study participants, “We hypothesize that [the improvement in overall survival] is based on greater awareness of prostate cancer and improved health-seeking behavior in African American men,” commented Thompson.
However, Thompson pointed out, African American men have a twofold to threefold greater incidence of newly diagnosed metastatic prostate cancer than do white men, which contributes to a similarly increased mortality rate. “A greater effort is needed to eliminate disparities in prostate cancer.”