(ChemotherapyAdvisor) – Prostate-specific antigen (PSA) testing detects a significant number of high- to intermediate-risk T1cN0M0 stage prostate cancers among African American men as well as elderly men of any race or ethnicity, according to a large, retrospective, population-based analysis presented at the 4th annual 2013 Genitourinary Cancers Symposium in Orlando, FL.

T1cN0M0 stage prostate cancers are asymptomatic and are rarely detected during physical exam or diagnostic imaging, noted lead author Hong Zhang, MD, PhD, of the University of Rochester in New York.

But “a substantial number of PSA-detected prostate cancer patients have either intermediate or high-risk disease at diagnosis,” Dr. Zhang reported. “Men 75 years of age or older or of black race have the highest risk of presenting with intermediate- or high-risk disease.”

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The study included data from 70,345 men in the United States with T1cN0M0 prostate cancer, 47.6% of whom had low-risk disease. Another 35.9% and 16.5% of all men in the study had intermediate- and high-risk disease, respectively.

Of all men with high-risk T1cN0M0 prostate cancer, 40% were older than 75, Dr. Zhang noted—representing a nearly 9.4-fold increased probability of high-risk disease compared to that seen among men younger than age 50 (odds ratio [OR], 9.39; 95% CI: 7.25-12.16; P<0.01).

African American men of all ages faced a 1.8-fold higher probability of high-risk disease, compared to Caucasians (OR for high-risk disease, 1.84; 95% CI: 1.72-19.97; P<0.01), Dr. Zhang added. African American men of any age were already known to be twice as likely to die of prostate cancer as other US populations, Dr. Zhang noted.

The US Preventative Services Task Force recently recommended against PSA screening for the general US population because of harms associated with unnecessary treatment among men with PSA-detected tumors that would likely have remained asymptomatic throughout life.  That recommendation was followed by declines in PSA testing for all age groups.

But older men (> 75 years) and African-American men may benefit from PSA screening even if they are asymptomatic, Dr. Zhang cautioned.

“If we stop PSA screening altogether, we have no other way to detect this form of prostate cancer sufficiently early to have the best chance of helping this group of high-risk patients,” Dr. Zhang explained. “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 effect of early detection and intervention on outcome in these high-risk patients.”

The 2013 Genitourinary Cancers Symposium is co-sponsored by the American Gastroenterological Association (AGA) Institute, the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO) and the Society of Urologic Oncology (SUO).