Prostate Cancer Charity: http://www.prostate-cancer.org.uk/
Requires Adobe Reader to view: www.dh.gov.uk/assetRoot/04/06/38/07/04063807.pdf
Poor reliability of the PSA
prostate cancer blood test.
Punglia RS et al New England Journal of Medicine
2003 July; 349:335-42 (accessed on line 2/8/03)
Between 1995 and 2001, 6691 men underwent
PSA-based screening for prostate cancer. Of these men, 705 (11 percent)
subsequently underwent biopsy of the prostate and 182 had prostate cancer.
However, in men under age 60 who had prostate cancer the PSA test was normal
(less than 4 ng/ml) in 82%. In those over age 60, 65% would be missed. In the
men with levels above 4, 2% did not have prostate cancer on subsequent biopsy.
The authors calculated that lowering the threshold to 2.6 ng/ml would detect 36%
of the cancers but at the cost of increasing the number of false positives (i.e.
negative biopsies).
An accompanying editorial confirmed the lack of evidence that the PSA test
reduces the risk of death from prostate cancer without reducing men's quality of
life.
(The American Cancer Society's current
recommendations advise that PSA between 4 and 10 means a 25% risk of having
prostate cancer with a 67% risk above 10)
Informed consent for cancer
screening with prostate-specific antigen: how well are men getting the message?
Chan ECY et al. Am J Public Health 2003 May;
93:779-85.
OBJECTIVES: This study examined knowledge about
prostate-specific antigen (PSA) screening among African Americans and Whites.
Because PSA screening for prostate cancer is controversial, professional
organizations recommend informed consent for screening.
METHODS: Men (n = 304) attending outpatient clinics were surveyed for their
knowledge about and experience with screening.
RESULTS: Most men did not know the key facts about screening with PSA. African
Americans appeared less knowledgeable than Whites, but these differences were
mediated by differences in educational level and experience with prostate cancer
screening.
The researchers surveyed 271 men (age, 50 or older) who were patients
at 2 hospital medicine clinics. Of 213 who had heard of PSA tests,
84% reported that they were told by their physicians to have PSA
testing, and 82% reported undergoing PSA tests. Nevertheless, only
40% said that their physicians discussed the advantages and
disadvantages of the PSA test with them. On a 36-question assessment
of knowledge about prostate cancer, screening, and treatment,
respondents answered only about half of the questions correctly, on
average. About 95% of respondents believed that "regular prostate
cancer screening lowers mortality," and 80% believed that "doctors
are sure that PSA tests are useful." There were minor differences in
responses between white and black patients, but patterns of response
were similar.
CONCLUSIONS: Public health efforts to improve informed consent for prostate
cancer screening
should focus on highlighting the key facts and developing different approaches
for men at different levels of formal education and prior experience with
screening.
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Annual PSA Screening Is Unnecessary in Some Men
Hugosson J et al. Prostate specific antigen based biennial screening is
sufficient to detect almost all prostate cancers while still curable. J Urol
2003 May; 169:1720-3
The idea of a yearly interval for prostate-specific antigen (PSA) screening
derives from the old habit of performing screening tests annually. However,
there is no biological evidence that 1 year is the ideal interval. Researchers
from the ongoing European Randomized Screening for Prostate Cancer trial suggest
that biennial screening is appropriate for some men.
In the Swedish arm of the trial, 5854 men (age range, 50-65) underwent baseline
PSA screening. The 660 men with PSA levels of 3 ng/mL or higher were referred
for biopsy; the remaining men were rescreened 2 years later. Of 2950 men with
baseline PSA levels lower than 1.0 ng/mL, none had a level of 3.0 ng/mL or
higher on the 2-year follow-up test. Although the authors conclude that biennial
screening would be appropriate for men with initial PSA levels as high as 2.0
ng/mL, the article provides inadequate detail about outcomes in men with initial
PSA levels between 1.0 and 2.0 ng/mL.
Data (currently available only in abstract form) from the other large ongoing
PSA screening trial -- the PLCO trial in the U.S. -- support the European data.
At the 2002 American Society of Clinical Oncology annual meeting, the PLCO
investigators announced that 99% of men with initial PSA levels lower than 1.0
ng/mL still had levels lower than 4.0 ng/mL after 4 years of annual screening.
Among those with initial levels between 1.0 and 2.0 ng/mL, 99% still had levels
lower than 4.0 ng/mL after 1 year (ASCO meeting abstract; accessed May 13,
2003).
Comment by Allan S. Brett, MD published in Journal Watch May 16, 2003:
For men who are undergoing prostate cancer screening, these findings suggest
that yearly PSA testing is unnecessary when the initial value is lower than 1.0
ng/mL and possibly when it's lower than 2.0 ng/mL. Of course, these
observations will become meaningful only if the U.S. and European trials
ultimately show that PSA screening reduces prostate cancer mortality.
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In December 2002, the U.S. Preventive Services
Task Force (USPSTF) concluded that "the evidence is insufficient to recommend
for or against routine screening for prostate cancer using prostate specific
antigen (PSA) testing or digital rectal examination (DRE)".
Rationale: The USPSTF found
good evidence that PSA screening can detect early-stage prostate cancer but
mixed and inconclusive evidence that early detection improves health outcomes.
Screening is associated with important harms, including frequent
false-positive results and unnecessary anxiety, biopsies, and potential
complications of treatment of some cancers that may never have affected a
patient's health. The USPSTF concludes that evidence is insufficient to
determine whether the benefits outweigh the harms for a screened population.
This link also has links to the latest evidence
considered by the task force:
http://www.ahrq.gov/clinic/uspstf/uspsprca.htm
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2005 update: Another Salvo in the PSA Controversy
Many men with prostate-specific antigen (PSA) levels lower than the traditional cut-off (4 ng/mL) for biopsy have occult prostate cancer, leading some authorities to argue that the threshold should be lowered. Dartmouth researchers used PSA data from the National Health and Nutrition Examination Survey (2001–2002), and other data on prostate cancer treatment and mortality rates, to estimate the effects of lowering the PSA cut-off to 2.5 ng/mL. At the 4 ng/mL cutoff, about 1.5 million American men (age range, 40–69) would be labelled as having abnormal PSA levels. If the cutoff were lowered to 2.5 ng/mL, an additional 1.8 million men would be labelled as having abnormal levels. If those 1.8 million men underwent biopsies, 450,000 would be diagnosed with prostate cancer. If all 450,000 underwent radical prostatectomy, 180,000 would become impotent, 40,000 would have at least moderate incontinence, and
1000 would die from the surgery.
Among men aged 50 to 59, 11% have PSA levels higher than 2.5 ng/mL, but only 0.3% are likely to die from prostate cancer in the next 10 years (according to statistics from the pre-PSA era). Among men aged 60 to 69, these figures are 17% and 0.9%, respectively.
Comment: These researchers note that only a tiny fraction of men with PSA levels higher than 2.5 ng/mL will die from prostate cancer during the next 10 years, but large numbers of these men would be subjected to morbidity associated with surgery. The authors, who clearly are sceptical about PSA screening, conclude that lowering the PSA threshold "would be a mistake." — Allan S. Brett, MD Published in Journal Watch August 26, 2005
Source: Welch HG et al. Prostate-specific antigen levels in the United States: Implications of various definitions for abnormal. J Natl Cancer Inst 2005 Aug 3; 97:1132-7.
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Prostate cancer blood test may not cut death rate
Source: The Guardian Date: 10/01/2006
The PSA test, the most widely-used test for prostate cancer, may not reduce the risk of men dying from the disease, according to research by the Veterans Affairs Connecticut Healthcare System in New Haven and Yale University. Research at the institute has found that, following the examination of approximately 72,000 older men receiving healthcare, that 70 of the men who died and 65 of those who had lived underwent a PSA test, leading the scientists to conclude that the test proved to be of little effectiveness. The results are to be published in the US journal Archives of Internal Medicine.
The Minster Practice, Lichfield
