A new article in the New England Journal of Medicine this week has updated the prostate cancer-specific and all-cause (overall) mortality data from the European Randomized Study of Screening for Prostate Cancer (ERSPC).
This latest analysis of data by Schröder et al., and based on a randomized comparison of screening (with regularly scheduled PSA tests) as opposed to non-screening, has shown the following results in the predefined, core group of men aged between 55 and 69 years at the time of enrollment:
- The average (median) follow-up for men in the core group was 11 years.
- There was no significant difference in all-cause mortality between the groups who were or were not screened for risk of prostate cancer.
- Reductions in the risk for prostate cancer-specific mortality in men randomized to the screening group as compared to the unscreened group were
- An absolute reduction of 0.10 prostate cancer deaths per 1,000 person-years
- An absolute reduction of 1.07 prostate cancer deaths per 1,000 men who underwent screening
- A relative overall reduction in the risk of prostate cancer deaths in the screening group of 21 percent
- A relative overall reduction in the risk of prostate cancer deaths in the screening group of 29 percent after adjustment for non-compliance with screening
- To prevent a single case of prostate cancer-specific mortality
- 1,055 men would need to be invited to be screened
- 37 cases of prostate cancer would need to be detected
The authors conclude that this analysis, which adds two additional years of follow-up data to the data originally published in early 2009, shows that “PSA-based screening significantly reduced mortality from prostate cancer but did not affect all-cause mortality.”
For those who are not familiar with this study (the largest study of screening for prostate cancer ever carried out), it enrolled 182,160 men (from eight European nations) between the ages of 50 and 74 years at study entry. It included a predefined core group of 162,388 men aged between 55 and 69 years of age. Men were randomly assigned to either the screening group (who were offered regular PSA-based screening tests) or to a control group (who were not offered such screening). The primary outcome was prostate cancer-specific mortality. The first report of data from this trial was published in early 2009 based on a median 9 years of follow-up.
These new data are unlikely to help to clarify the debate over the value of mass screening for prostate cancer. From one point of view one can use them to argue that screening can prevent between 20 and 30 percent of prostate cancer-specific deaths. From the alternative point of view, one can argue that screening a million men would indeed prevent about 950 prostate cancer-specific deaths, but would also lead to the potential over-treatment of 36 out of every 37 cases of prostate cancer identified, and would have no impact whatsoever on overall mortality.