Prostate cancer screening using blood samples may do more
harm than good, according to a European study now being cited
here in favour of restrictions on the testing.
Researchers in France re-analysed results of a large European
study on screening of men without symptoms with the prostate
specific antigen (PSA) blood test.
The original study reported a 20 per cent fall in prostate
cancer deaths for men in the screening group.
But the reanalysis included estimates on the number of deaths
from prostate cancer treatment and deaths from complications,
such as major infection, after biopsy tissue samples being
taken from the prostate. The original study found for every
1055 men screened, 37 prostate cancers were detected and one
prostate cancer death was avoided. This equated to a gain of
of 9.3 years of life.
But the reanalysis, published in the journal of the British
Association of Urological Surgeons, calculated screening 1055
men and detecting 37 cancers would also lead to the loss of
3.2 years of life from treatment deaths and 9.7 years from
biopsy deaths. The collective loss from biopsy deaths was
based on the assumption each of these men would have lived
17.1 more years on average.
The researchers said the net loss of life, for every 1055 men
screened, would be 3.6 years. "It appears that screening
would generate more harm - in terms of lost years of life -
than good," the researchers say. "Unless the mortality rate
associated with prostate biopsy can be decreased, screening
for prostate cancer with PSA should be discouraged."
Associate Professor Brian Cox, a cancer epidemiologist at
Otago University, said the new study was further evidence PSA
testing of asymptomatic men "should be severely restricted or
cease". Many of the cancers diagnosed would never cause
problems in the man's lifetime.
More than 40 per cent of men over 50 in New Zealand have had
PSA testing. Prostate cancer was the most commonly diagnosed
cancer in 2009, with 3369 new cases. It was the third most
common cause of cancer death for men, with 562 deaths.
The prostate is a gland the size of a golf ball in front of
the rectum. It produces some of the fluid in semen.
The Government has not set up a screening programme because
of the uncertainties about PSA testing. The Health Ministry
urges doctors to provide "balanced information on prostate
cancer and the possible benefits and harms of testing and
treatment".
The Urological Society of Australia and New Zealand says men
aged 55 to 69 should be offered PSA testing and digital
rectal examination.
Professor Cox said screening programmes were based on the
principle of participants' average chance of benefiting
exceeding the chance of harm.
"This report suggests someone who doesn't have symptoms
having PSA testing probably has a greater chance of
shortening their life than lengthening it."
- Martin Johnston of the New Zealand Herald
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