Younger men amenable to PSA testing
Controversy continues to rage over the feasibility of PSA screening for prostate cancer.
This study, in the BMJ, is a prospective cohort study taken from the ProtecT study, an ongoing randomised controlled trial of screening for prostate cancer, comprising a group of men aged 50-69.
This nested study investigated the uptake of PSA testing, the prevalence of prostate cancer and characteristics of the disease in men aged 45-49.
Between November 2003 and August 2005, 1,299 men in Sheffield were invited to participate. Of these, 442 (34%) agreed to have a PSA test. This compares with an uptake of 50% in patients aged 50-69 in ProtecT.
Participants with a PSA level >1.5 were invited for a transrectal ultrasound-guided prostate biopsy. Fifty-four men had a PSA level above the threshold and 47 agreed to a biopsy. Ten cases of prostate cancer were detected; the positive predictive value of a raised PSA level was 21.3%.
Of the ten cases of prostate cancer found, five were classified as potentially indolent (based on an unvalidated nomogram) and five as of potential clinical significance.
The study shows that men under 50 will accept PSA testing, although at significantly lower rates than the over 50s, and that a PSA threshold of 1.5 results in a comparable detection rate to that in older men with a PSA threshold of 3.0.
Studies have suggested that screening for prostate cancer should start at age 45. Extrapolating the study results to the UK national population of 2,236,000 men aged 45-49 suggests 272,905 raised PSA levels and 51,449 cases of prostate cancer – how many of these patients would benefit from treatment?
However, the 221,456 men with negative biopsies and the side-effects of treatment have to be considered.
It is likely that most clinicians will continue to recommend PSA testing in the under 50s only in patients with a significant family history or of Afro-Caribbean origin.
Lane JA, Howson J, Donovan JL et al. Detection of prostate cancer in unselected young men: prospective cohort nested within a randomised controlled trial. BMJ 2007;335:1139–44Reviewer
Dr Jonathan Rees
GPwSI Urology, Bristol