Hong Zhang, MD, PhD
A large, retrospective study has found that high-risk prostate cancer that can only be detected through prostate-specific antigen (PSA) testing is more likely to occur among men over the age of 75 and in African Americans, according to research reported at the 2013 Genitourinary (GU) Cancers Symposium.
The findings come amid a continuing debate over the merits of PSA screening, particularly after the US Preventive Services Task Force (USPSTF) recommended against routine screening for the general male population last May based on the finding that the harms of overdiagnosis outweigh the potential benefits of screening.
The results of the study presented this week suggest that PSA testing can be useful in identifying an aggressive form of prostate cancer in asymptomatic men with early disease that is not detectable by physical exam or other tests.
In their population-based study, researchers from the University of Rochester Medical Center in New York determined that elderly men account for approximately 40% of all cases of high-risk, PSA-detected prostate cancer and are 9.4 times more likely than men under the age of 50 to be high risk. African-American men of any age are more likely than white men to have high-risk disease.
In addition, intermediate-risk prostate cancer was more likely to occur among elderly and African-American men, the study found.
“To the best of our knowledge, this is the largest analysis exclusively consisting of PSA-detected prostate cancer (T1cN0M0 disease). We found that men age 75 and older and African Americans are at highest risk of intermediate or high-risk disease,” stated lead author Hong Zhang, MD, PhD, an associate professor of Radiation Oncology at the University of Rochester, during a press conference where the results were announced.
“If we stop PSA screening altogether, there is no other method to detect this form of prostate cancer sufficiently early to have the best chance of helping this group of high-risk patients,” Zhang said. “The findings of this study will help physicians and certain patients make more informed decisions on whether or not they want to proceed with PSA testing, although more research (and longer follow-up) is needed to determine the effects of early detection and intervention on outcome in these high-risk patients.”
The study included 70,345 men with early-stage, node-negative prostate cancer diagnosed between 2004-2008 enrolled in the Surveillance, Epidemiology and End Results (SEER) database.
PSA criteria and Gleason stage were utilized to determine the probability of developing low-, intermediate-, and high-risk prostate cancer. Low risk was defined as PSA <10 ng/mL and Gleason score ≤6; intermediate risk was defined as PSA 10-20 ng/mL and/or Gleason score 7; and high-risk disease was defined as PSA >20 ng/mL and/or Gleason score ≥8.
Among the study population, 47.6% had low-risk disease; 35.9% had intermediate-risk, and 16.5% had high-risk.
Men age 75 or older were 4.47 times more likely to develop intermediate-risk disease and nearly 9.4 times more likely to develop high-risk prostate cancer compared with patients under the age of 50 (P
<.01 for both comparisons).
African-American men were also significantly more likely to develop intermediate- and high-risk disease compared with white men; they were 1.5 times more likely to develop intermediate-risk prostate cancer and 1.84 times more likely to develop high-risk prostate cancer (P
<.01 for both comparisons).
By comparison, white men age 75 or older accounted for 11.8% of this population, including 24.3% of intermediate- and 26.1% of high-risk disease.
Bruce J. Roth, MD, who moderated the press conference where these data were discussed, said the study showed that numeric age probably is not the most important determinant of who should be screened and that perhaps life expectancy within an age group should be taken into consideration.
The American Society of Clinical Oncology (ASCO) provisional clinical opinion call for men with a life expectancy of more than 10 years to discuss PSA screening with their physicians.
“Screening recommendations have been all over the map, ranging from ‘everyone should be screened’ above the age of 50 to ‘no one should be screened’,” said Roth, who is a professor of Medicine at Washington University in St. Louis, Missouri. “The answer is somewhere in between, and this study gives us some important information but adds to the complexity of this issue.”
The GU symposium is co-sponsored by ASCO, the American Society for Radiation Oncology, and the Society of Urologic Oncology.
Zhang H, Travis LB, Messing EM, et al. PSA-detected prostate cancer in the United States: a population-based study of 70,345 men with AJCC stage T1cN0M0 disease. Presented at: 4th Annual Genitourinary Cancers Symposium; February 14-16, 2013; Orlando, FL. Abstract 50.
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