As reported in Futurity.org today, PSA testing and early detection may prevent up to 17,000 cases of metastatic prostate cancer a year, a new study suggests.
Eliminating the prostate-specific antigen (PSA) test to screen for prostate cancer would likely result in rising numbers of men with metastatic cancer at the time of diagnosis, according to the analysis published in the journal Cancer.
“Our findings are very important in light of the recent controversy over PSA testing,” says Edward M. Messing, study co-author, chair of urology at the University of Rochester Medical Center, and president of the Society of Urologic Oncology, in the Futurity.org piece. “Yes, there are trade-offs associated with the PSA test and many factors influence the disease outcome. And yet our data are very clear: not doing the PSA test will result in many men presenting with far more advanced prostate cancer. And almost all men with metastasis at diagnosis will die from prostate cancer.”
In 2011 the U.S. Preventive Services Task Force recommended against PSA screening in all men, prompting criticism from the medical community. The government panel reviewed scientific evidence and concluded that screening has little or no benefit, or that the harms of early detection outweigh the benefits.
The Task Force recommendations against screening caused some confusion, and in response, a special panel of experts from the American Society of Clinical Oncology issued its own opinion: for men with a life expectancy of less than 10 years, general screening with the PSA test should be discouraged. For men with a longer life expectancy, though, it is recommended that physicians discuss with patients whether the PSA test is appropriate for them.
Messing’s study looked back at the era prior to 1986, when no one was routinely screened for prostate cancer with a PSA test. To analyze the effect of screening on stage of disease at initial diagnosis, Messing and Emelian Scosyrev, assistant professor of urology, reviewed data from 1983 to 2008 kept by the nation’s largest cancer registry, Surveillance, Epidemiology and End-Results
, or SEER.
They compared SEER data from the pre-PSA era (1983 to 1985) to the current era of widespread PSA use (2006 to 2008), and adjusted for age, race, and geographic variations in the U.S. population.
Approximately 8,000 cases of prostate cancer with metastases at initial presentation occurred in the United States in 2008. Using a mathematical model to estimate the number of metastatic cases that would be expected to occur in 2008 in the absence of PSA screening, Scosyrev and Messing predict the number would be 25,000.
The authors emphasize the study was observational and has some limitations. In particular it is impossible to know if the PSA test and early detection is solely responsible for the fewer cases of metastasis at diagnosis in 2008.