Screening for Prostate Cancer
A new analysis has found that doing away with PSA (prostate specific antigen) testing for prostate cancer would likely cause three times as many men to develop advanced disease that has spread to other parts of the body before being diagnosed. Published early online in CANCER, a peer-reviewed journal of the American Cancer Society, the study suggests that PSA testing and early detection may prevent approximately 17,000 men each year from having such advanced prostate cancer at diagnosis.
PSA testing has come under fire recently as a potentially ineffective screen for prostate cancer. Last year a government panel reviewed the available evidence and concluded that PSA testing has little or no benefit and that doctors are finding and treating non-aggressive cancers that are not likely to cause symptoms or be lethal. Therefore, many men may be experiencing serious treatment side effects such as incontinence and erectile dysfunction for no reason.
Comparing Pre- and Post-Routine-Testing Data
To see what might happen if PSA testing were abandoned, Edward Messing, MD, of the University of Rochester Medical Center, USA, and his team looked at information from the years immediately before routine PSA testing was done (1983–1985) and compared it to the current era of widespread PSA testing (2006–2008). The information for the analysis came from the nation’s largest cancer registry, the Surveillance, Epidemiology, and End Results (SEER) database. The researchers were particularly interested in the records of patients who had advanced prostate cancer that had already spread to other parts of the body at the time of diagnosis. These cases are generally incurable and always cause significant symptoms very quickly if left untreated.
The investigators found that approximately 8,000 cases of prostate cancer had already spread to distant sites (i.e., metastases) at the time of diagnosis in the United States in 2008 (the most recent SEER year). Next, they 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 screening had not been done. They predicted the number would be approximately 25,000, which is about three times greater than the number actually observed.
“Our findings are very important in light of the recent controversy over PSA testing,” said Dr. 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,” he added.
Prostate cancer is the second leading cause of cancer death in the male population. In 2012 an estimated 241,740 new cases will be diagnosed and 28,000 deaths will occur. Prognosis depends on whether the cancer has spread, and the degree to which the cancer cells are abnormal.
- Prostate-specific antigen screening for prostate cancer and the risk of overt metastatic disease at presentation: analysis of trends over time,
Emil Scosyrev, Guan Wu, Supriya Mohile, Edward Messing,