672
U N I T 7
Kidney and Urinary Tract Function
lined with neoplastic epithelium. Although these tumors
may recur and rarely invade the underlying bladder
wall, they are seldom life-threatening.
59,60
High-grade carcinomas can be papillary or flat; they
tend to cover larger areas of the mucosal surface and
carry a high risk of invasion into the detrusor muscle
and surrounding tissues, and when associated with inva-
sion, a significant metastatic potential. Bladder cancers
are commonly staged according to the TNM classifica-
tion (see Chapter 7) of the World Health Organization
(WHO) with stage T3 carcinomas invading perivesical
tissues and T4 carcinomas spreading to adjacent organs
and distant metastases.
59–61
Etiology and Pathogenesis
Although the cause of bladder cancer is unknown, evi-
dence suggests that its origin is related to local influ-
ences, such as carcinogens that are excreted in the urine
and stored in the bladder.
57–62
Cigarette smoking is an
important risk factor, with 30% to 50% of all bladder
cancers among males who are current or past smok-
ers. Other risk factors include the presence of arsenic
in the drinking water and industrial exposure to the
breakdown products of aromatic amines used in the dye
industry and to chemicals used in the manufacture of
rubber, textiles, paint, and petroleum products.
62
Both
the heavy long-term use of cyclophosphamide, an immu-
nosupressive agent, and prior exposure to bladder radi-
ation, often administered for other pelvic malignancies,
also increase the risk of bladder cancer. Bladder cancer
also occurs more frequently among persons harboring
Schistosoma haematobium
, a parasite that is endemic in
Egypt and Sudan, in their bladder.
59,61
Manifestations
The most common sign of bladder cancer is painless
hematuria.
58–61
Gross hematuria is a presenting sign in
75% of persons with the disease, and microscopic hema-
turia is present in most others. Frequency, urgency, and
dysuria occasionally accompany the hematuria. Because
hematuria often is intermittent, the diagnosis may be
delayed. Periodic urine cytology is recommended for
all persons who are at high risk for the development
of bladder cancer because of exposure to urinary tract
carcinogens. Ureteral invasion leading to bacterial and
obstructive renal disease and dissemination of the cancer
are potential complications and ultimate causes of death.
The prognosis depends on the histologic grade of the can-
cer and the stage of the disease at the time of diagnosis.
Diagnosis andTreatment
Diagnostic methods include cytologic studies, excretory
urography, cystoscopy, and biopsy. Ultrasonography,
CT scans, and MRI are used as aids for staging the
tumor. Cytologic studies performed on biopsy tissues or
cells obtained from bladder washings may be used to
detect the presence of malignant cells.
59
The treatment of bladder cancer depends on the type
and extent of the lesion and the health of the patient.
Endoscopic resection usually is done for diagnostic
purposes and may be used as a treatment for superfi-
cial lesions. For small papillary tumors that are not high
grade, the initial diagnostic transurethral resection may
be the only surgical procedure done. Segmental surgi-
cal resection may be used for removing a large single
lesion. When the tumor is invasive, a cystectomy with
resection of the pelvic lymph nodes frequently is the
treatment of choice. Cystectomy requires urinary diver-
sion, an alternative reservoir, usually created from the
ileum (e.g., an ileal loop), that is designed to collect the
urine. External-beam radiation therapy is an alternative
to radical cystectomy in some patients with deeply infil-
trating bladder cancer.
59
Surgical treatment of superficial bladder cancer is
often followed by intravesicular chemotherapy or immu-
notherapy, a procedure in which the therapeutic agent is
directly instilled into the bladder. One of the agents used
for this purpose is an attenuated strain of the tubercu-
losis bacillus, called
bacillus Calmette-Guérin
(BCG),
which elicits an inflammatory response that destroys the
tumor. Patients who are found to have regional inva-
sion or distant metastasis are often treated with systemic
chemotherapeutic agents. Therapy can be given before
planned cystectomy (neoadjuvant) in an attempt to
decrease recurrence or in some cases to allow for bladder
preservation. Alternatively, adjuvant chemotherapy may
administered after surgery to prevent tumor recurrence.
SUMMARY CONCEPTS
■■
Bladder cancers fall into two major groups:
low-grade noninvasive tumors and high-
grade invasive tumors that are associated with
metastasis and a worse prognosis.
■■
Although the cause of cancer of the bladder is
unknown, evidence suggests that carcinogens
excreted in the urine may play a role. Cigarette
smoking is an important risk factor. Other risk
factors include the presence of arsenic in the
drinking water and exposure to industrial chemicals.
■■
Microscopic and gross painless hematuria are the
most frequent presenting signs of bladder cancer.
The methods used in treatment of bladder cancer
depend on the cytologic grade of the tumor and
the lesion’s degree of invasiveness.
■■
Treatment methods include surgical removal of
the tumor, radiation therapy, and chemotherapy.
In many cases, chemotherapeutic or immuno
therapeutic agents can be instilled directly into
the bladder, thereby avoiding the side effects of
systemic therapy.
