U.S. Cancer Screening Trial Shows No Early Mortality Benefit from Annual Prostate Cancer Screening
Six annual screenings for prostate cancer led to more diagnoses of the disease, but no fewer prostate cancer deaths, according to a major new report from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, a 17-year project of the National Cancer Institute. The PLCO was designed to provide answers about the effectiveness of prostate cancer screening.
Balintfy: The Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial is looking to see if screening for those diseases can help to lower mortality. Results from a report appear online in a recent issue of the New England Journal of Medicine.
Berg: This particular report focused only on prostate cancer.
Balintfy: Dr. Christine Berg is the National Cancer Institute leader of the PLCO trial and senior author of the study.
Berg: And the straightforward analysis shows that at seven years of follow-up there was no decrease in death in the group that got actively screened compared to the group that got screened by their local physicians. However, there were 500 more cancers found. So, we still saw 50 deaths in the actively screened group, 44 deaths in the less-actively screened group, but we had 2,800 cancers in the actively screened group and 2,300 cancers in the less-actively screened group, so detecting 500 more cancers did not prevent those other 50 deaths.
Balintfy: There were more than 76, 000 men in the PLCO trial that was conducted at ten centers around the United States. Of the men in the trial, roughly 38, 000 were randomly assigned to screening, including annual prostate-specific antigen or PSA tests; the other 38,350 men were randomly assigned to usual care, but received no recommendations for or against annual prostate cancer screening. Dr. Berg explains that the difference between the numbers of deaths in the two groups was not statistically significant. Thus there was no detectable mortality benefit for screening vs. usual-care.
Berg: And so when a man who is deciding whether to be screened or not needs to put this whole picture together. He needs to weigh his own individualized risk, based on his age and family history and race—African-American men tend to be at a somewhat higher risk—and he needs to look at his other health conditions and he needs to talk with his physician or his urologist.
Balintfy: NCI does not have a recommendation about prostate cancer screening. The U.S. Preventive Services Task Force, whose recommendations are considered the gold standard for clinical preventive services, recently concluded that there is insufficient evidence to assess the balance of benefits and harms of prostate cancer screening in men younger than age 75 and recommended against prostate cancer screening in men age 75 and older. But, Dr. Berg emphasizes that information from the PLCO trial will help.
Berg: This is leading towards our holy grail of individualized medicine. However, it comes with uncertainty in the process of us getting that information. It's a very complex mixture before we can say, "All right, you, gentleman sitting in my office today, this is what you're chances are in the future." And then it's still going to be measures of risks and benefits and individual risk tolerance.
Balintfy: Dr. Berg adds that the NCI wants to understand why some prostate cancers are lethal even when found early by annual screening, and what approaches can be used to identify these more aggressive cancers when they can be effectively treated. For more information on this study and cancer research, visit www.cancer.gov. This is Joe Balintfy, National Institutes of Health, Bethesda, Maryland.