Though they found more cancers, annual prostate screening and manual exams did not improve mortality in a large-scale study of men over a 13-year period, a new study suggests.
A total of 76,685 men aged 55-74 were enrolled in the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial, which initially lasted between November 1993 and December 2009, though screening was completed in October 2006. The randomized two-arm trial was conducted by U.S. and Canadian researchers at 10 screening centres.
In the trial, 38,340 men were part of the intervention group and received an annual PSA (prostate-specific antigen) test for six years and a rectal exam every year. The control group, comprising of 38,345 men, received usual care and occasional screening if warranted.
When researchers conducted a follow-up with study participants 13 years after the beginning of the trial, they found a 12 per cent increase in the incidence of prostate cancer in men in the intervention group versus men in the control group. A non-statistically significant decrease in the incidence of advanced prostate cancer was also noted in the group that received more intensive screening.
However, there was no difference in mortality between the group that had extra screening and the group that received regular care. Researchers attribute this to better prostate cancer treatments and the fact that men in the control group did have some screening — roughly half of what the intervention group received.
Researchers found that more men actually died of other causes than the cancers studied in the trial, both in the extra screening group and the control group.
"Among these deaths, intervention and control arms showed 23 per cent and 22 per cent deaths, respectively, from non- PLCO cancers, and 21 per cent and 19 per cent deaths respectively, from ischemic heart disease," the authors write.
Ischemic heart disease is characterized by reduced blood supply to the heart.
The authors believe the results show extra screening is not warranted.
"There is no evidence of a benefit. Indeed, there is evidence of harms, in part associated with the false-positive tests but also with the over-diagnosis inseparable from PSA screening, especially in older men."
The study was published Friday in the Journal of the National Cancer Institute.