world cancer report - iarc
world cancer report - iarc
world cancer report - iarc
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SCREENING FOR PROSTATE CANCER<br />
SUMMARY<br />
> Prostate-specific antigen (PSA) testing is<br />
widely used for the early detection of<br />
prostate <strong>cancer</strong>.<br />
> Elevated levels of PSA are closely, but<br />
not definitively, associated with prostate<br />
<strong>cancer</strong>; false positive results may lead to<br />
unnecessary treatment.<br />
> Assessment of population-based PSA<br />
screening suggests a reduction in mortality<br />
in countries with access to urological<br />
follow-up and treatment.<br />
Secondary prevention of prostate <strong>cancer</strong><br />
is feasible, but is subject to controversy,<br />
since the capacity to detect early disease<br />
must inevitably result in overtreatment for<br />
the individual patient, with substantial<br />
costs to society, in exchange for<br />
decreased mortality [1]. The lack of effective,<br />
appropriate markers of disease and<br />
any reasonable consensus on subsequent<br />
treatment necessitates extensive patient<br />
counselling as an important prerequisite,<br />
with some degree of prudence until the<br />
outcomes of the ongoing randomized trials<br />
in Europe and North America have<br />
been evaluated and audited [2].<br />
Biological basis of secondary<br />
prevention<br />
Prostate-specific antigen (PSA), a glycoprotein,<br />
is a proteinase that is responsible<br />
for the liquefaction of semen. PSA analysis<br />
has replaced prostatic acid phosphatase<br />
as the preferred serum marker of<br />
prostate <strong>cancer</strong>. The fact that PSA is highly<br />
tissue-specific and the consideration<br />
that few prostatic conditions result in a<br />
sustained, elevated level of serum PSA<br />
have made it the most efficacious marker<br />
currently available for the detection of<br />
prostate <strong>cancer</strong>. A serum “cut-off level” of<br />
4 ng/ml for normality was used to demon-<br />
160 Prevention and screening<br />
Fig. 4.37 A physician in discussion with a patient:<br />
informed consent is a prerequisite for PSA testing.<br />
strate the efficacy of PSA as a diagnostic<br />
tool [3]. Unfortunately, 25% of patients<br />
diagnosed with prostate <strong>cancer</strong> have levels<br />
of serum PSA that are less than 4<br />
ng/ml. Of men with PSA levels between 4-<br />
10 ng/ml, 25% have <strong>cancer</strong>, and 60% have<br />
<strong>cancer</strong> when PSA levels are greater than<br />
10 ng/ml.<br />
PSA analysis should be combined with a<br />
digital rectal examination, the latter providing<br />
an assessment of the volume of the<br />
gland, since PSA is also released into the<br />
bloodstream of patients with benign<br />
prostate hyperplasia and other prostatic<br />
diseases. To improve the sensitivity of the<br />
PSA analysis, a number of parameters<br />
Advantages Disadvantages<br />
may be assessed, most of which relate to<br />
concomitant benign prostate hyperplasia<br />
and also include age-specific reference<br />
ranges [4], typical values being: 40-49<br />
years,