SAN ANTONIO (Aug. 23, 2012) – PSA testing may be under fire by the U.S. Preventive Services Task Force, but a paper published today in the Journal of Urology by a local researcher shows that prostate cancer deaths have declined sharply since it came into regular use.
The “PSA era” — the era in which PSA testing for prostate cancer became routine for about half of the men in the U.S. — began in 1990. Since then, the rate of men dying from prostate cancer has dropped by 44 percent. What’s more, the study found that the enormous disparity in death rates for African American and Caucasian men with advanced disease has shrunk to the point of insignificance.
Ian M. Thompson Jr., M.D., director of the Cancer Therapy & Research Center at The University of Texas Health Science Center at San Antonio, worked with Catherine M. Tangen, Ph.D., of the Fred Hutchison Cancer Research Center in Seattle to analyze the data from three large studies starting in the mid-1980s, and they concluded that PSA testing has a proven positive role in assessing prostate cancer risk.
“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,” Dr. Thompson said.
Prostate cancer is the most common cancer in men, and the PSA (prostate-specific antigen) test is commonly used to look for the markers of prostate cancer.
The PSA test has come under fire for being overused to diagnose prostate cancer without taking other factors into account. The U.S. Preventive Services Task Force recommended in May that doctors stop doing routine PSA tests on men of any age.
The task force members looked at data from three different studies suggesting that a focus on PSA screening and treatment in recent years has had marginal benefits at great cost.
But the new analysis stands in contrast to their conclusions.
Dr. Thompson and Dr. Tangen looked at data from three clinical trials done through SWOG, a multi-institutional group that conducts nationwide cancer clinical trials. The studies evaluated patient survival after androgen deprivation treatment (ADT) for prostate cancer.
Median survival in the first trial, which enrolled patients from 1985 to 1986, was 30 months, and median survival in the second, which enrolled patients from 1989 to 1994, was 33 months. In contrast, median survival in the third trial, which enrolled patients from 1995 to 2009, was 49 months.
“What this really means is that PSA testing has an entire range of effects,” Dr. Thompson said. “As shown in an enormous European study of screening, simply screening men with PSA will save some lives. It also means that even if you find the disease when it’s advanced — even then — you get a big benefit by finding it earlier. In so many ways, so many lives are saved.”
For African-American men in the first trial, median survival was 27 months, while in the last trial analyzed, their survival rate had increased to 48 months.
“We hypothesize that this improvement is based on greater awareness of prostate cancer among African-American men, and more willingness to see a doctor about it,” Dr. Thompson said. However, African-American men have a two- to three-fold greater incidence of newly diagnosed metastatic prostate cancer compared to white men, and that contributes to a similarly increased mortality rate. “More work is needed to eliminate disparities in prostate cancer,” Dr. Thompson said.
Dr. Thompson has been critical of overreliance on the PSA test, which can lead to unnecessary treatment in healthy men. But he argues that it is an important diagnostic tool, and he and his colleagues designed the Prostate Cancer Risk Calculator, available on the UT Health Science Center website, so that doctors and patients can more easily incorporate PSA counts with other information that would affect a man’s risk.
The Cancer Therapy & Research Center (CTRC) at The University of Texas Health Science Center at San Antonio is one of the elite academic cancer centers in the country to be named a National Cancer Institute (NCI) Designated Cancer Center, and is one of only four in Texas. A leader in developing new drugs to treat cancer, the CTRC Institute for Drug Development (IDD) conducts one of the largest oncology Phase I clinical drug programs in the world, and participates in development of cancer drugs approved by the U.S. Food & Drug Administration. For more information, visit www.ctrc.net.