July 30, 2012
PSA Testing: Are We Better Off With Or Without It?
Lawrence LeBlond for redOrbit.com - Your Universe Online
Recent studies have suggested that PSA testing for prostate cancer is an unneeded medical screening process that often does more harm than good. However, a new report, published in the journal Cancer, states that eliminating the PSA test would be taking a big step backward and would likely result in a rising number of men who develop the advanced disease that has spread to other areas of the body before a diagnosis is made.
The study, by researchers at University of Rochester Medical Center (URMC), suggests that the prostate-specific antigen (PSA) test may prevent up to 17,000 cases of metastatic prostate cancer a year. The study points to data that shows if age-specific pre-PSA era incidence rates were to occur in the present day, as many as 33 percent more men would have cancer that has already spread before diagnosis.
The issue of PSA testing has been heavily probed recently, with a government panel review finding that the available evidence concluded that the controversial test offered little benefit and that doctors are finding and treating non-aggressive cancers that are unlikely to be lethal. The panel said that many men would experience serious treatment side effects such as incontinence and erectile dysfunction for no reason.
Study coauthor Edward Messing, MD, of URMC, said recommendations to abandon PSA testing are premature and harmful. To see what might happen of PSA testing was in fact abandoned, he and his colleagues looked at information from years immediately before routine PSA testing was done (1983-85) and compared it to the current era of widespread testing (2006-08).
Messing gleaned the information from the nation´s largest cancer registry -- the Surveillance, Epidemiology, and End Results (SEER) database. The team looked mainly at records of patients who had advanced prostate cancer that had already spread to other areas of the body at the time of diagnosis.
They discovered that about 8,000 cases of prostate cancer had already spread at the time of diagnosis in the US in 2008. They then designed a mathematical model that used pre-PSA incidence rates of metastatic disease from the mid-1980s to estimate the number of such advanced cases that would be expected to occur in 2008 if PSA testing had not been done; that number was 25,000, or three times as many the actual number observed.
“Our findings are very important in light of the recent controversy over PSA testing,” said Messing. “Although there are trade-offs associated with the PSA test and many factors influence the disease outcome, our data clearly indicate that not doing the PSA test will result in many more men presenting with far advanced prostate cancer. Almost all men with clinically apparent metastases at initial diagnosis will die from prostate cancer.”
Messing and colleagues emphasized the study was only observational and had limitations. In particular it is impossible to know if the PSA screening process and early detection is solely responsible for the fewer cases of metastasis at diagnosis in 2008.
The study did conclude, however, that PSA awareness efforts during the 1990s and early 2000s resulted in substantial shifts toward earlier-stage disease and fewer cases of metastases at diagnosis.
Prostate cancer is the second leading cause of cancer death in the male population. In 2012 about 241,740 new cases will be diagnosed and 28,000 deaths will occur. Prognosis depends on whether the cancer has spread outside the prostate gland, and to the degree to which the cancer cells are abnormal.
The URMC study was funded by the Ashley Family Foundation.