medwireNews: A single prostate-specific antigen (PSA) screening test does not reduce prostate cancer mortality at 10 years, but does significantly increase the number of diagnoses, UK study data confirm.
“Although longer-term follow-up is under way, the findings do not support single PSA testing for population-based screening,” conclude Richard Martin (University of Bristol) and co-investigators from the CAP (Cluster Randomized Trial of PSA Testing for Prostate Cancer) clinical trial group.
For the CAP trial, 573 primary care practices across the UK were randomly assigned to provide a prostate cancer screening intervention in which men aged 50 to 69 years were invited to attend a PSA testing clinic and receive a single PSA test, or to continue providing standard (unscreened) care, only giving information about PSA testing to men who requested it. Men with a PSA level of 3 ng/mL or greater underwent standardized prostate biopsy.
Of the 189,386 men in the intervention group, 75,707 (40%) attended the PSA testing clinic, 67,313 (36%) underwent PSA testing, and 5850 (3%) had a prostate biopsy.
The researchers report in JAMA that the rate of prostate cancer diagnoses was significantly higher in the intervention group (4.3%) than in the control group (3.6% of 219,439), with incidence rates of 4.45 and 3.80 cases per 1000 person–years, respectively.
This was mainly due to a significantly higher rate of lower grade tumors (Gleason grade ≤6) being detected in the intervention group, at 1.7% versus 1.1%.
However, after a median follow-up period of 10 years, the prostate cancer mortality rate did not differ significantly between the intervention and control groups, at 0.30 versus 0.31 deaths per 1000 person–years, respectively.
There was also no difference in all-cause mortality between the groups.
Martin and co-authors say the CAP trial “provides new evidence that complements published trials such as [the European] ERSPC and [the US-based] PLCO,” controversies surrounding which have resulted in different recommendations for screening worldwide.
In an accompanying editorial, Michael Barry, from Harvard Medical School in Boston, Massachusetts, USA, writes: “A key question is whether the findings from the CAP trial should swing the pendulum further in the direction of not offering screening PSA tests.
“Based on the CAP results, an offer of a single PSA screen in a population of men aged 50 to 59 years is ineffective, and given the higher risk of a prostate cancer diagnosis this approach engenders, likely does more harm than good,” he says.
Barry adds that active surveillance programs “appear to be helpful” but cautions that “[h]ow ‘active’ active surveillance needs to be and which men are candidates requires further research.”
By Laura Cowen
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