world cancer report - iarc

Fig. 5.82 Risk of bladder cancer among men who smoke relative to never-smokers, according to daily cigarette
consumption.
leather manufacturing, as a painter and as
a barber or hairdresser have been variously
associated with increased risk. The
uncertainty surrounding these associations
is partly due to difficulty in measuring
past exposure to specific chemical
agents.
In common with cancer of the renal pelvis, a
consistent relationship has been observed
between use of phenacetin-containing analgesics
and bladder cancer, with relative risks
varying from 2.4 to over 6-fold. Use of the
anticancer drug cyclophosphamide, an alkylating
agent, has been strongly and consistently
linked to bladder cancer. Non-Hodgkin
lymphoma patients treated with cyclophosphamide
therapy have a dose-dependent
increased risk of bladder cancer.
Infection by the trematode worm,
Schistosoma haematobium, is associated
with an up to five-fold increased risk. In
endemic areas, which include most of Africa
and in several West Asian countries, infection
as a result of ingestion of contaminated
water occurs from childhood (Fig. 5.83), and
risk of bladder cancer, especially of the
squamous cell type, increases as from the
third decade of life. The infection is responsible
for about 10% of bladder cancer cases
in the developing world and about 3% of
cases overall [4].
Decreased risk of bladder cancer is associated
with consumption of foods rich in
vitamin A and carotenoids; evidence concerning
a risk associated with coffee consumption
is inconsistent.
Detection
Detection of neoplastic alterations in exfoliated
bladder cells collected in the urine
has been proposed as a screening
approach for bladder cancer, in particular
among industrial workers potentially
exposed to aromatic amines, but there is
no evidence in favour of its effectiveness.
Other methods are also under investigation
[5].
Haematuria, usually painless, is the presenting
symptom for the majority of
patients with bladder cancer. Patients
may also present with bladder irritability,
including urinary frequency, urgency and
dysuria. Diagnosis is made by urine analysis
and after visualization of the bladder
by ultrasound and cystoscopy. Tissue for
histopathological analysis may be
obtained through transurethral resection.
Pathology and genetics
Approximately 90% of bladder cancers are
classified as transitional cell carcinoma
and are believed to originate in intraepithelial
neoplastic transformation of the
bladder transitional epithelium. The localized
proliferation of transformed cells can
give rise to a carcinoma in situ, which may
Fig. 5.83 A canal in a poor housing district in
Egypt. Such canals may provide a habitat for the
snails which are host to Schistosoma parasites.
Chronic infection with Schistosoma haematobium
causes cystitis and often bladder cancer.
Fig. 5.84 Carcinoma in situ of the bladder; the
normal transitional epithelium has been replaced
by a disorganized, poorly-differentiated cell layer
(arrows).
T
Fig. 5.85 Transitional cell carcinoma of the bladder,
moderately differentiated, with a papillary
architecture. B = blood vessel, T = tumour.
take several clinical forms, not necessarily
associated with high grade or high risk
of progression (Fig. 5.84) [6]. Spread can
occur by growth into the submucosa and
muscularis of the bladder wall (25% of
cases). About 70% of transitional cell carcinomas
are of the papillary type (Fig.
5.85) and do not invade the muscularis
propria of the bladder wall, 10% are
described as nodular and 20% as mixed.
B
T
T
Bladder cancer
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